EP2855723B1 - Nickel-chromium-aluminium alloy with good formability, creep strength and corrosion resistance - Google Patents

Description

The invention relates to a nickel-chromium-aluminum alloy having excellent high temperature corrosion resistance, creep resistance and improved processability.

Austenitic nickel-chromium-aluminum alloys with different nickel, chromium and aluminum contents have long been used in furnace construction and in the chemical and petrochemical industries. For this application, a good high-temperature corrosion resistance is required even in carburizing atmospheres and a good heat resistance / creep resistance.

In general, it should be noted that the high temperature corrosion resistance of the alloys listed in Table 1 increases with increasing chromium content. All these alloys form a chromium oxide layer (Cr ₂ O ₃ ) with an underlying, more or less closed, Al ₂ O ₃ layer. Small additions of strongly oxygen-affinitive elements such as Y or Ce improve the oxidation resistance. The content of chromium is slowly consumed in the course of use in the application area for the formation of the protective layer. Therefore, a higher chromium content increases the life of the material, since a higher content of the protective layer-forming element chromium retards the time at which the Cr content is below the critical limit and forms oxides other than Cr ₂ O ₃ , eg ferrous and nickel containing oxides are. A further increase in high temperature corrosion resistance can be achieved by adding aluminum and silicon. From a certain minimum content, these elements form a closed layer below the chromium oxide layer and thus reduce the consumption of chromium.

In carburizing atmospheres (CO, H ₂ , CH ₄ , CO ₂ , H ₂ O mixtures, carbon can penetrate into the material, resulting in the formation of internal carbides, resulting in loss of notched impact strength the melting point drops to very low levels (up to 350 ° C) and chromium depletion of the matrix can occur.

High resistance to carburization is achieved by materials with low solubility for carbon and low diffusion rate of carbon. Nickel alloys are therefore generally more resistant to carburization than iron-base alloys because both carbon diffusion and carbon solubility in nickel are lower than in iron. Increasing the chromium content results in a higher carburization resistance by forming a protective chromium oxide layer, unless the oxygen partial pressure in the gas is insufficient to form this protective chromium oxide layer. At very low oxygen partial pressures, materials can be used which form a layer of silicon oxide or the even more stable alumina, both of which can form protective oxide layers even at significantly lower oxygen contents.

In the case that the carbon activity is> 1, so-called "metal dusting" can occur with nickel-, iron- or cobalt-base alloys. In contact with the supersaturated gas, the alloys can absorb large amounts of carbon. The segregation processes occurring in the carbon-supersaturated alloy lead to material destruction. The alloy decomposes into a mixture of metal particles, graphite, carbides and / or oxides. This type of material destruction occurs in the temperature range of 500 ° C to 750 ° C.

Typical conditions for the occurrence of metal dusting are strongly carburizing CO, H ₂ or CH ₄ gas mixtures, as they occur in ammonia synthesis, in methanol plants, in metallurgical processes, but also in hardening furnaces.

The resistance to metal dusting tends to increase with increasing nickel content of the alloy ( Grabke, HJ, Krajak, R., Müller-Lorenz, EM, Strauss, S .: Materials and Corrosion 47 (1996), p. 495 ), however, nickel alloys are not generally resistant to metal dusting.

The chromium and aluminum content has a significant influence on the corrosion resistance under metal dusting conditions (see Figure 1). Low chromium nickel alloys (such as alloy Alloy 600, see Table 1) show comparatively high corrosion rates under metal dusting conditions. The nickel alloy Alloy 602 CA (N06025) with a chromium content of 25% and an aluminum content of 2.3% as well as Alloy 690 (N06690) with a chromium content of 30% is significantly more resistant ( Hermse, CGM and van Wortel, JC: Metal Dusting: relationship between alloy composition and degradation rate. Corrosion Engineering, Science and Technology 44 (2009), p. 182 - 185 ). Resistance to metal dusting increases with the sum Cr + AL.

The heat resistance or creep resistance at the specified temperatures is u. a. improved by a high carbon content. However, high contents of solid solution hardening elements such as chromium, aluminum, silicon, molybdenum and tungsten also improve the heat resistance. In the range of 500 ° C to 900 ° C, additions of aluminum, titanium and / or niobium can improve the strength by excretion of the y'- and / or γ "-phase.

Examples of the prior art are listed in Table 1.

Alloys such as Alloy 602 CA (N06025), Alloy 693 (N06693) or Alloy 603 (N06603) are superior in their corrosion resistance compared to Alloy 600 (N06600) or Alloy 601 (N06601) due to the high aluminum content of more than 1.8 % known. Alloy 602 CA (N06025), Alloy 693 (N06693), Alloy 603 (N06603) and Alloy 690 (N06690) show excellent carburization resistance or metal dusting resistance due to their high chromium and / or aluminum content. At the same time, alloys such as Alloy 602 CA (N06025), Alloy 693 (N06693) or Alloy 603 are shown (N06603), because of the high carbon and aluminum contents, excellent hot strength or creep resistance occurs in the temperature range in the metal dusting. Alloy 602 CA (N06025) and Alloy 603 (N06603) have excellent heat resistance and creep resistance even at temperatures above 1000 ° C. However, z. For example, the high aluminum content impairs processability, and the higher the aluminum content, the stronger the deterioration (for example, for Alloy 693 - N06693). The same applies to an increased degree for silicon, which forms low-melting intermetallic phases with nickel. In Alloy 602 CA (N06025) or Alloy 603 (N06603) in particular the cold workability is limited by a high proportion of primary carbides.

The US 6,623,869B1 discloses a metallic material consisting of not more than 0.2% C, 0.01-4% Si, 0.05-2.0% Mn, not more than 0.04% P, not more than 0.015% S, 10 - 35% Cr, 30 - 78% Ni, 0.005 - <4.5% Al, 0.005 - 0.2% N, and at least one of the elements 0.015 - 3% Cu and 0.015 - 3% Co, with the balance consists of 100% iron. In this case, the value of 40Si + Ni + 5Al + 40N + 10 (Cu + Co) is not less than 50, the symbols of the elements meaning the content of the corresponding elements. The material has excellent corrosion resistance in an environment where metal dusting can take place and therefore can be used for stovepipes, piping systems, heat exchanger tubes and the like. Ä. Used in petroleum refineries or petrochemical plants and can significantly improve the life and safety of the plant.

The EP 0 508 058 A1 discloses an austenitic nickel-chromium-iron alloy consisting of (in weight%) C 0.12-0.3%, Cr 23-30%, Fe 8-11%, Al 1.8 2.4% , Y 0.01 - 0.15%, Ti 0.01 - 1.0%, Nb 0.01 - 1.0%, Zr 0.01 - 0.2%, Mg 0.001 - 0.015%, Ca 0.001 - 0.01%, N max. 0.03%, Si max. 0.5%, Mn max. 0.25%, P max. 0.02%, S max. 0.01%, Ni remainder, including unavoidable melt contaminants.

The US 4,882,125 B1 discloses a chromium-containing nickel alloy which, with excellent resistance to desulfurization and oxidation at temperatures greater than 1093 ° C, has excellent creep resistance of more than 200 hours at temperatures above 983 ° C and a tension of 2000 PSI, good tensile strength and good Elongation, both at room temperature and elevated temperatures, consisting of (in% by weight) 27-35% Cr, 2.5-5% Al, 2.5-6% Fe, 0.5-2.5% Nb, up to 0.1% C, up to 1% each of Ti and Zr, up to 0.05% Ce, up to 0.05% Y, up to 1% Si, up to 1% Mn and Ni remainder.

The EP 0 549 286 B1 discloses a high temperature resistant Ni-Cr alloy including 55-65% Ni, 19-25% Cr1-4.5% Al, 0.045-0.3% Y, 0.15-1% Ti, 0.005-0.5 % C, 0.1-1.5% Si, 0-1% Mn and at least 0.005%, at least one of the elements of the group containing Mg, Ca, Ce, <0.5% in total Mg + Ca, <1 % Ce, 0.0001 - 0.1% B, 0 - 0.5% Zr, 0.0001 - 0.2% N, 0 - 10% Co, 0 - 0.5% Cu, 0 - 0.5 % Mo, 0-0.3% Nb, 0-0.1% V, 0-0.1% W, balance iron and impurities.

By the DE 600 04 737 T2 For example, a heat-resistant nickel-based alloy has been known, comprising ≦ 0.1% C, 0.01-2% Si, ≦ 2% Mn, ≦ 0.005% S, 10-25% Cr, 2.1- <4.5% Al, ≤ 0.055% N, in total 0.001-1% of at least one of the elements B, Zr, Hf, wherein said elements may be present in the following contents: B ≤ 0.03%, Zr ≤ 0.2%, Hf ≤ 0.8 %. Mo 0.01 - 15%, W 0.01 - 9%, whereby a total content Mo + W of 2.5 - 15% may be given, Ti 0 - 3%, Mg 0 - 0.01%, Ca 0 - 0.01%, Fe 0-10%, Nb 0-1%, V 0-1%, Y 0-0.1%, La 0-0.1%, Ce 0 0.01%, Nd 0 0.1%, Cu 0-5%, Co 0-5%, remainder nickel. For Mo and W the following formula must be fulfilled: $$\mathrm{2}.\mathrm{5}\le \mathrm{Not\; a\; word}+\mathrm{W}\le \mathrm{15}$$

Of the US 5,997,809 For example, consider an alloy for high temperature applications including 27 to 35% chromium, 0 to 7% iron, 3 to 4.4% aluminum, 0 to 0.14% titanium, 0.2 to 3% niobium, 0.12 to 0 , 5% carbon, 0 to 0.05% zirconium, 0.002 to 0.05% in total cerium + yttrium, 0 to 1% manganese, 0 to 1% silicon, 0 to 0.5% calcium + magnesium, 0 to 0.1% boron, balance nickel as well as impurities.

• eine gute Phasenstabilität
• eine gute Verarbeitbarkeit
• eine gute Korrosionsbeständigkeit an Luft, ähnlich der von Alloy 602 CA (N06025)
• eine gute Warmfestigkeit / Kriechfestigkeit aufweist.

The object underlying the invention is to design a nickel-chromium-aluminum alloy, which ensures excellent metal dusting resistance at sufficiently high chromium and aluminum contents, but at the same time

• a good phase stability
• a good processability
• good corrosion resistance in air, similar to Alloy 602 CA (N06025)
• has a good heat resistance / creep resistance.

und $$\mathrm{Fp}\le 39,9\mathrm{mit}$$

$$\mathrm{Fp}=\mathrm{Cr}+\mathrm{0},\mathrm{272}*\mathrm{Fe}+\mathrm{2},\mathrm{36}*\mathrm{Al}+\mathrm{2},\mathrm{22}*\mathrm{Si}+\mathrm{2},\mathrm{48}*\mathrm{Ti}+\mathrm{0},\mathrm{374}*\mathrm{Mo}+\mathrm{0},\mathrm{538}*\mathrm{W}-\mathrm{11},\mathrm{8}*\mathrm{C}$$

wobei Cr, Fe, Al, Si, Ti, Mo, W und C die Konzentration der betreffenden Elemente in Masse-% sind, wobei bei Einsatz von Nb die Formel 4a um einen Term mit Nb ergänzt wird: $$\mathrm{Fp}=\mathrm{Cr}+\mathrm{0},\mathrm{272}*\mathrm{Fe}+\mathrm{2},\mathrm{36}*\mathrm{Al}+\mathrm{2},\mathrm{22}*\mathrm{Si}+\mathrm{2},\mathrm{48}*\mathrm{Ti}+\mathrm{1},\mathrm{26}*\mathrm{Nb}+\mathrm{0},\mathrm{374}*\mathrm{Mo}+\mathrm{0},\mathrm{538}*\mathrm{W}-\mathrm{11},\mathrm{8}*\mathrm{C}$$

und Cr, Fe, Al, Si, Ti, Nb, Mo, W und C die Konzentration des betreffenden Elementes in Masse % sind.Nickel-chromium-aluminum alloy, with (in% by weight) 24 to 33% chromium, 1.8 to <3.0% aluminum, 0.10 to <2.5% iron, 0.001 to 0.50% Silicon, 0.005 to 2.0% manganese, 0.00 to 0.60% titanium, each 0.0002 to 0.05% magnesium and / or calcium, 0.005 to 0.12% carbon, 0.001 to 0.050% nitrogen, 0 , 0001 - 0.020% oxygen, 0.001 to 0.030% phosphorus, max. 0.010% sulfur, max. 2.0% molybdenum, max. 2.0% tungsten, optionally Nb 0.001 - <0.50%, further optionally containing Y with a content of 0.01 to 0.20%, La with a content of 0.001 to 0.20%, cerium with a content from 0.001 to 0.20%, cerium misch metal having a content of 0.001 to 0.20%, Zr having a content of from 0.01 to 0.20%, B having a content of from 0.0001 to 0.008%, Co to 5.0%, Cu up to max. 0.5%, max. 0.5% V, balance nickel and the usual process-related impurities, the following relationships must be fulfilled: $$\mathrm{Cr}+\mathrm{al}\ge 28$$

and $$\mathrm{fp}\le 39.9\mathrm{With}$$

$$\mathrm{fp}=\mathrm{Cr}+\mathrm{0}.\mathrm{272}*\mathrm{Fe}+\mathrm{2}.\mathrm{36}*\mathrm{al}+\mathrm{2}.\mathrm{22}*\mathrm{Si}+\mathrm{2}.\mathrm{48}*\mathrm{Ti}+\mathrm{0}.\mathrm{374}*\mathrm{Not\; a\; word}+\mathrm{0}.\mathrm{538}*\mathrm{W}-\mathrm{11}.\mathrm{8th}*\mathrm{C}$$

wherein Cr, Fe, Al, Si, Ti, Mo, W and C are the concentration of the respective elements in mass%, wherein the formula 4a is supplemented by a term with Nb when using Nb: $$\mathrm{fp}=\mathrm{Cr}+\mathrm{0}.\mathrm{272}*\mathrm{Fe}+\mathrm{2}.\mathrm{36}*\mathrm{al}+\mathrm{2}.\mathrm{22}*\mathrm{Si}+\mathrm{2}.\mathrm{48}*\mathrm{Ti}+\mathrm{1}.\mathrm{26}*\mathrm{Nb}+\mathrm{0}.\mathrm{374}*\mathrm{Not\; a\; word}+\mathrm{0}.\mathrm{538}*\mathrm{W}-\mathrm{11}.\mathrm{8th}*\mathrm{C}$$

and Cr, Fe, Al, Si, Ti, Nb, Mo, W and C are the concentration of the respective element in mass%.

Advantageous developments of the subject invention can be found in the associated dependent claims.

• > 25 - < 30 %
• 25 bis 33 %
• 26 bis 33 %
• 27 bis 32 %
• 27 bis 31 %
• 27 bis 30 %
• 27,5 bis 29,5 %
• 29 bis 31 %

The chrome spreading range is between 24 and 33%, with preferred ranges being set as follows:

• > 25 - <30%
• 25 to 33%
• 26 to 33%
• 27 to 32%
• 27 to 31%
• 27 to 30%
• 27.5 to 29.5%
• 29 to 31%

• 1,8 bis 3,2 %
• 2,0 bis 3,2 %
• 2,0 bis <3,0 %
  2,0 bis 2,8 %
  2,2 bis 2,8 %
• 2,2 bis 2,6 %
• 2,4 bis 2,8 %
• 2,3 bis 2,7 %

The aluminum content is between 1.8 and 4.0%, whereby here too, depending on the area of use of the alloy, preferred aluminum contents can be set as follows:

• 1.8 to 3.2%
• 2.0 to 3.2%
• 2.0 to <3.0%
  2.0 to 2.8%
  2.2 to 2.8%
• 2.2 to 2.6%
• 2.4 to 2.8%
• 2.3 to 2.7%

• 0,1 - 4,0 %
• 0,1 - 3,0 %
• 0,1 - < 2,5 %
• 0,1 - 2,0 %
• 0,1 - 1,0 %

The iron content is between 0.1 and 7.0%, whereby, depending on the field of application, preferred contents can be set within the following spreading ranges:

• 0.1 - 4.0%
• 0.1 - 3.0%
• 0.1 - <2.5%
• 0.1 - 2.0%
• 0.1 - 1.0%

• 0,001 - 0,20 %
• 0,001 - <0,10 %
• 0,001 - <0,05 %.
• 0,010 - 0,20 %

The silicon content is between 0.001 and 0.50%. Preferably, Si within the spreading range can be set in the alloy as follows:

• 0.001 - 0.20%
• 0.001 - <0.10%
• 0.001 - <0.05%.
• 0.010 - 0.20%

• 0,005 - 0,50 %
• 0,005 - 0,20 %
• 0,005 - 0,10 %
• 0,005 - <0,05 %
• 0,010 - 0,20 %

The same applies to the element manganese, which may be contained in the alloy with 0.005 to 2.0%. Alternatively, the following spread range is conceivable:

• 0.005 - 0.50%
• 0.005 - 0.20%
• 0.005 - 0.10%
• 0.005 - <0.05%
• 0.010 - 0.20%

• 0,001 - 0,60 %,
• 0, 001 - 0,50 %
• 0,001 - 0,30 %
• 0,01 - 0,30 %
• 0,01 - 0,25 %

The titanium content is between 0.0 and 0.60%. Preferably, Ti within the spreading range can be adjusted in the alloy as follows:

• 0.001 - 0.60%,
• 0, 001 - 0.50%
• 0.001 - 0.30%
• 0.01 - 0.30%
• 0.01 - 0.25%

• 0,0002 - 0,03 %
• 0,0002 - 0,02 %
• 0,0005 - 0,02 %

Also magnesium and / or calcium is contained in contents of 0.0002 to 0.05%. It is preferably possible to adjust these elements in the alloy as follows:

• 0.0002 - 0.03%
• 0.0002 - 0.02%
• 0.0005 - 0.02%

• 0,01 - 0,10 %
• 0,02-0,10%
• 0,03-0,10%

The alloy contains 0.005 to 0.12% carbon. Preferably, this can be adjusted within the spreading range in the alloy as follows:

• 0.01 - 0.10%
• 0.02-0.10%
• 0.03-0.10%

• 0,003 - 0,04 %

This applies equally to the element nitrogen, which is contained in contents between 0.001 and 0.05%. Preferred contents can be given as follows:

• 0.003 - 0.04%

• 0,001 - 0,020 %

The alloy further contains phosphorus at levels between 0.001 and 0.030%. Preferred contents can be given as follows:

• 0.001-0.020%

The alloy further contains oxygen in amounts between 0.0001 and 0.020%, in particular 0.0001 to 0.010%.

• Schwefel max. 0,010 %

The element sulfur is given in the alloy as follows:

• Sulfur max. 0.010%

• Mo max. 1,0 %
• W max. 1,0 %
• Mo max. < 0,50 %
• W max. <0,50 %
• Mo max. < 0,05 %
• W max. < 0,05 %

Molybdenum and tungsten are contained singly or in combination in the alloy each containing not more than 2.0%. Preferred contents can be given as follows:

• Mo max. 1.0%
• W max. 1.0%
• Mo max. <0.50%
• W max. <0.50%
• Mo max. <0.05%
• W max. <0.05%

The following relationship between Cr and Al must be satisfied in order to provide sufficient resistance to metal dusting: $$\mathrm{Cr}+\mathrm{al}\ge 28$$

$$\mathrm{Cr}+\mathrm{Al}\ge 30$$

$$\mathrm{Cr}+\mathrm{Al}\ge 31$$

Wherein Cr and Al are the concentration of the respective elements in mass%. Preferred areas can be set with $$\mathrm{Cr}+\mathrm{al}\ge 29$$

$$\mathrm{Cr}+\mathrm{al}\ge 30$$

$$\mathrm{Cr}+\mathrm{al}\ge 31$$

$$\mathrm{Fp}=\mathrm{Cr}+\mathrm{0},\mathrm{272}*\mathrm{Fe}+\mathrm{2},\mathrm{36}*\mathrm{Al}+\mathrm{2},\mathrm{22}*\mathrm{Si}+\mathrm{2},\mathrm{48}*\mathrm{Ti}+\mathrm{0},\mathrm{374}*\mathrm{Mo}+\mathrm{0},\mathrm{538}*\mathrm{W}-\mathrm{11},\mathrm{8}*\mathrm{C}$$

wobei Cr, Fe, Al, Si, Ti, Mo, W und C die Konzentration der betreffenden Elemente in Masse-% sind.In addition, the following relationship must be satisfied for sufficient phase stability: $$\mathrm{fp}\le 39.9\mathrm{With}$$

$$\mathrm{fp}=\mathrm{Cr}+\mathrm{0}.\mathrm{272}*\mathrm{Fe}+\mathrm{2}.\mathrm{36}*\mathrm{al}+\mathrm{2}.\mathrm{22}*\mathrm{Si}+\mathrm{2}.\mathrm{48}*\mathrm{Ti}+\mathrm{0}.\mathrm{374}*\mathrm{Not\; a\; word}+\mathrm{0}.\mathrm{538}*\mathrm{W}-\mathrm{11}.\mathrm{8th}*\mathrm{C}$$

wherein Cr, Fe, Al, Si, Ti, Mo, W and C are the concentration of the respective elements in mass%.

$$\mathrm{Fp}\le 36,6$$

Preferred ranges can be set with: $$\mathrm{fp}\le 38.4$$

$$\mathrm{fp}\le 36.6$$

• 0,01 - 0,15 %
• 0,01 - 0,10 %
• 0,01 - 0,08 %
• 0,01 - 0,05 %
• 0,01 - <0,045 %

Optionally, in the alloy, the element yttrium may be adjusted in amounts of 0.01 to 0.20%. Preferably, Y within the spreading range can be set in the alloy as follows:

• 0.01 - 0.15%
• 0.01 - 0.10%
• 0.01 - 0.08%
• 0.01 - 0.05%
• 0.01 - <0.045%

• 0,001 - 0,15 %
• 0,001 - 0,10 %
• 0,001 - 0,08%
• 0,001 - 0,05 %
• 0,01 - 0,05 %

Optionally, in the alloy, the element lanthanum may be adjusted in amounts of 0.001 to 0.20%. Preferably, within the spreading range, La can be set in the alloy as follows:

• 0.001 - 0.15%
• 0.001 - 0.10%
• 0.001-0.08%
• 0.001 - 0.05%
• 0.01 - 0.05%

• 0,001 - 0,15 %
• 0,001-0,10%
• 0,001 - 0,08%
• 0,001 - 0,05 %
• 0,01 - 0,05 %

Optionally, in the alloy, the element Ce may be adjusted in amounts of 0.001 to 0.20%. Preferably, Ce within the spreading range can be adjusted in the alloy as follows:

• 0.001 - 0.15%
• 0.001-0.10%
• 0.001-0.08%
• 0.001 - 0.05%
• 0.01 - 0.05%

• 0,001 - 0,15 %
• 0,001 - 0,10 %
• 0,001 - 0,08%
• 0,001 - 0,05 %
• 0,01 - 0,05 %

Optionally, with the simultaneous addition of Ce and La, it is also possible to use cerium misch metal in amounts of from 0.001 to 0.20%. Preferably, cerium misch metal within the spreading range can be adjusted in the alloy as follows:

• 0.001 - 0.15%
• 0.001 - 0.10%
• 0.001-0.08%
• 0.001 - 0.05%
• 0.01 - 0.05%

• 0,001 - < 1,10 %
• 0,001 - <0,70 %
• 0,001 - <0,50 %
• 0,001 - 0,30 %
• 0,01 - 0,30 %
• 0,10 - 1,10 %
• 0,20 - 0,70 %
• 0,10-0,50%

Optionally, in the alloy, the element Nb may be adjusted at levels of from 0.0 to 1.10%. Preferably, Nb within the spreading range can be adjusted in the alloy as follows:

• 0.001 - <1.10%
• 0.001 - <0.70%
• 0.001 - <0.50%
• 0.001 - 0.30%
• 0.01 - 0.30%
• 0.10 - 1.10%
• 0.20 - 0.70%
• 0.10-0.50%

wobei Cr, Fe, Al, Si, Ti, Nb, Mo, W und C die Konzentration des betreffenden Elementes in Masse % sind.If Nb is present in the alloy, formula 4a must be supplemented by a term with Nb as follows: $$\mathrm{fp}=\mathrm{Cr}+\mathrm{0}.\mathrm{272}*\mathrm{Fe}+\mathrm{2}.\mathrm{36}*\mathrm{al}+\mathrm{2}.\mathrm{22}*\mathrm{Si}+\mathrm{2}.\mathrm{48}*\mathrm{Ti}+1.26*\mathrm{Nb}+\mathrm{0}.\mathrm{374}*\mathrm{Not\; a\; word}+\mathrm{0}.\mathrm{538}*\mathrm{W}-\mathrm{11}.\mathrm{8th}*\mathrm{C}$$

where Cr, Fe, Al, Si, Ti, Nb, Mo, W and C are the concentration of the respective element in mass%.

• 0,01 - 0,15 %
• 0,01 - <0,10 %
• 0,01 - 0,07 %
• 0,01 - 0,05 %

If necessary, zirconium can be used in amounts between 0.01 and 0.20%. Preferably Zr can be adjusted within the spreading range in the alloy as follows:

• 0.01 - 0.15%
• 0.01 - <0.10%
• 0.01 - 0.07%
• 0.01 - 0.05%

• 0,001 - 0,20 % Hafnium.

Optionally, zirconium can also be replaced in whole or in part by

• 0.001-0.20% hafnium.

Optionally, the alloy may also contain from 0.001 to 0.60% tantalum.

• 0,0001 - 0,008 %

Optionally, the element boron may be included in the alloy as follows:

• 0.0001 - 0.008%

• 0,0005 - 0,008 %
• 0,0005 - 0,004 %

Preferred contents can be given as follows:

• 0.0005 - 0.008%
• 0.0005 - 0.004%

• 0,01 bis 5,0 %
• 0,01 bis 2,0 %
• 0,1 bis 2,0 %
• 0,01 bis 0,5 %

Furthermore, the alloy may contain between 0.0 to 5.0% cobalt, which may be further limited as follows:

• 0.01 to 5.0%
• 0.01 to 2.0%
• 0.1 to 2.0%
• 0.01 to 0.5%

Furthermore, a maximum of 0.5% Cu may be contained in the alloy.

• Cu max. <0,05 %
• Cu max. <0,015 %.

The content of copper may be further limited as follows:

• Cu max. <0.05%
• Cu max. <0.015%.

wobei Cr, Fe, Al, Si, Ti, Cu, Mo, W und C die Konzentration des betreffenden Elementes in Masse % sind.If Cu is contained in the alloy, formula 4a must be supplemented by a term with Cu as follows: $$\mathrm{fp}=\mathrm{Cr}+\mathrm{0}.\mathrm{272}*\mathrm{Fe}+\mathrm{2}.\mathrm{36}*\mathrm{al}+\mathrm{2}.\mathrm{22}*\mathrm{Si}+\mathrm{2}.\mathrm{48}*\mathrm{Ti}+0.477*\mathrm{Cu}+\mathrm{0}.\mathrm{374}*\mathrm{Not\; a\; word}+\mathrm{0}.\mathrm{538}*\mathrm{W}-\mathrm{11}.\mathrm{8th}*\mathrm{C}$$

wherein Cr, Fe, Al, Si, Ti, Cu, Mo, W and C are the concentration of the respective element in mass%.

wobei Cr, Fe, Al, Si, Ti, Nb, Cu, Mo, W und C die Konzentration des betreffenden Elementes in Masse % sind.If Nb and Cu are contained in the alloy, formula 4a must be supplemented by a term with Nb and a term with Cu as follows: $$\mathrm{fp}=\mathrm{Cr}+\mathrm{0}.\mathrm{272}*\mathrm{Fe}+\mathrm{2}.\mathrm{36}*\mathrm{al}+\mathrm{2}.\mathrm{22}*\mathrm{Si}+\mathrm{2}.\mathrm{48}*\mathrm{Ti}+1.26*\mathrm{Nb}+0.477*\mathrm{Cu}+\mathrm{0}.\mathrm{374}*\mathrm{Not\; a\; word}+\mathrm{0}.\mathrm{538}*\mathrm{W}-\mathrm{11}.\mathrm{8th}*\mathrm{C}$$

wherein Cr, Fe, Al, Si, Ti, Nb, Cu, Mo, W and C are the concentration of the respective element in mass%.

Furthermore, a maximum of 0.5% vanadium may be present in the alloy.

Finally, impurities may still contain the elements lead, zinc and tin in amounts as follows: pb Max. 0.002% Zn Max. 0.002% sn Max. 0.002%.

$$\mathrm{Fa}=\mathrm{Cr}+\mathrm{20},\mathrm{4}*\mathrm{Ti}+\mathrm{201}*\mathrm{C}$$

wobei Cr, Ti und C die Konzentration der betreffenden Elemente in Masse-% sind.Furthermore, optionally, the following relationship can be satisfied, which describes a particularly good processability: $$\mathrm{fa}\le 60\mathrm{With}$$

$$\mathrm{fa}=\mathrm{Cr}+\mathrm{20}.\mathrm{4}*\mathrm{Ti}+\mathrm{201}*\mathrm{C}$$

where Cr, Ti and C are the concentration of the respective elements in mass%.

Preferred ranges can be set with: $$\mathrm{fa}\le 54$$

wobei Cr, Nb, Ti und C die Konzentration der betreffenden Elemente in Masse-% sind.If Nb is included in the alloy, the formula 6a must be supplemented by a term with Nb as follows: $$\mathrm{fa}=\mathrm{Cr}+\mathrm{6}.\mathrm{15}*\mathrm{Nb}+\mathrm{20}.\mathrm{4}*\mathrm{Ti}+\mathrm{201}*\mathrm{C}$$

wherein Cr, Nb, Ti and C are the concentration of the respective elements in mass%.

$$\mathrm{Fk}=\mathrm{Cr}+\mathrm{19}*\mathrm{Ti}+\mathrm{10},\mathrm{2}*\mathrm{Al}+\mathrm{12},\mathrm{5}*\mathrm{Si}+\mathrm{98}*\mathrm{C}$$

wobei Cr, Ti, Al, Si und C die Konzentration der betreffenden Elemente in Masse-% sind.Furthermore, optionally the following relationship can be fulfilled, which describes a particularly good hot strength or creep resistance: $$\mathrm{Fk}\ge 45\mathrm{With}$$

$$\mathrm{Fk}=\mathrm{Cr}+\mathrm{19}*\mathrm{Ti}+\mathrm{10}.\mathrm{2}*\mathrm{al}+\mathrm{12}.\mathrm{5}*\mathrm{Si}+\mathrm{98}*\mathrm{C}$$

wherein Cr, Ti, Al, Si and C are the concentration of the respective elements in mass%.

$$\mathrm{Fk}\ge 53$$

Preferred ranges can be set with: $$\mathrm{Fk}\ge 49$$

$$\mathrm{Fk}\ge 53$$

wobei Cr, Ti, Nb, Al, Si, C und B die Konzentration der betreffenden Elemente in Masse-% sind.If Nb and / or B are contained in the alloy, formula 8a must be supplemented by a term with Nb and / or B as follows: $$\mathrm{Fk}=\mathrm{Cr}+\mathrm{19}*\mathrm{Ti}+\mathrm{34}.\mathrm{3}*\mathrm{Nb}+\mathrm{10}.\mathrm{2}*\mathrm{al}+\mathrm{12}.\mathrm{5}*\mathrm{Si}+\mathrm{98}*\mathrm{C}+\mathrm{2245}*\mathrm{B}$$

wherein Cr, Ti, Nb, Al, Si, C and B are the concentration of the respective elements in mass%.

The alloy of the invention is preferably melted open, followed by treatment in a VOD or VLF plant. But also a melting and pouring in a vacuum is possible. Thereafter, the alloy is poured in blocks or as a continuous casting. If necessary, the block is then at temperatures between Annealed 900 ° C and 1270 ° C for 0.1 h to 70 h. Furthermore, it is possible to remelt the alloy additionally with ESU and / or VAR. Thereafter, the alloy is brought into the desired semifinished product. For this, if necessary, annealed at temperatures between 900 ° C and 1270 ° C for 0.1 h to 70 h, then thermoformed, optionally with intermediate anneals between 900 ° C and 1270 ° C for 0.05 h to 70 h. The surface of the material may optionally (also several times) be removed chemically and / or mechanically in between and / or at the end for cleaning. After the end of the hot forming can optionally be a cold forming with degrees of deformation up to 98% in the desired semi-finished mold, possibly with intermediate anneals between 700 ° C and 1250 ° C for 0.1 min to 70 h, possibly under inert gas such. As argon or hydrogen, followed by cooling in air, carried out in the moving annealing atmosphere or in a water bath. Thereafter, a solution annealing in the temperature range of 700 ° C to 1250 ° C for 0.1 min to 70 h, optionally under inert gas, such as. As argon or hydrogen, followed by cooling in air, in the moving annealing atmosphere or in a water bath instead. Possibly. In between and / or after the last annealing chemical and / or mechanical cleaning of the material surface can take place.

The alloy according to the invention can be produced and used well in the product forms strip, sheet metal, rod wire, longitudinally welded tube and seamless tube.

These product forms are produced with an average particle size of 5 μm to 600 μm. The preferred range is between 20 μm and 200 μm.

The alloy according to the invention should preferably be used in areas in which carburizing conditions prevail, such as. As in components, especially pipes in the petrochemical industry. In addition, it is also suitable for furnace construction.

Accomplished tests:

The occurring phases in equilibrium were calculated for the different alloy variants with the program JMatPro from Thermotech. The database used for the calculations was the TTNI7 nickel base alloy database from Thermotech.

Mit L_u = Messlänge nach dem Bruch. The formability is determined in a tensile test according to DIN EN ISO 6892-1 at room temperature. The yield strength R _p0.2 , the tensile strength R _m and the elongation A are determined until the fracture. The elongation A is determined on the broken sample from the extension of the original measuring section L ₀ : $$\mathrm{A}=\left({\mathrm{L}}_{\mathrm{U}}-{\mathrm{<figure-callout\; id="0"\; label="L"\; filenames="imgf0002.png"\; state="\{\{state\}\}">L</figure-callout>}}_{\mathrm{0}}\right)/{\mathrm{<figure-callout\; id="0"\; label="L"\; filenames="imgf0002.png"\; state="\{\{state\}\}">L</figure-callout>}}_{\mathrm{0}}\mathrm{100}\%=\mathrm{.DELTA.L}/{\mathrm{<figure-callout\; id="0"\; label="L"\; filenames="imgf0002.png"\; state="\{\{state\}\}">L</figure-callout>}}_{\mathrm{0}}\mathrm{100}\%$$

With L _u = measuring length after the break.

• Z. B. ist für A₅ die Messlänge L₀ = 5·d₀ mit d₀ = Anfangsdurchmesser einer Rundprobe

Depending on the measuring length, the elongation at break is provided with indices:

• For example, for A ₅ the measuring length L ₀ = 5 · d ₀ with d ₀ = initial diameter of a round sample

The experiments were carried out on round samples with a diameter of 6 mm in the measuring range and a measuring length L ₀ of 30 mm. The sampling took place transversely to the forming direction of the semifinished product. The forming speed was 10 MPa / s at R _p0.2 and 40% / min at R _m 6.7 10 ^-3 .

The amount of elongation A in the tensile test at room temperature can be taken as a measure of the deformability. A good workable material should have an elongation of at least 50%.

The hot strength is determined in a hot tensile test according to DIN EN ISO 6892-2. The yield strength R _p0.2 , the tensile strength R _m and the Elongation A until break determined analogously to the tensile test at room temperature (DIN EN ISO 6892-1).

The experiments were carried out on round samples with a diameter of 6 mm in the measuring range and an initial measuring length L ₀ of 30 mm. The sampling took place transversely to the forming direction of the semifinished product. The forming speed at R _{p0.2 was} 8.33 10 ^-5 1 / s (0.5% / min) and at R _{m was} 8.33 10 ^-4 1 / s (5% / min).

The respective sample is installed at room temperature in a tensile testing machine and heated to a desired temperature without load with a tensile force. After reaching the test temperature, the sample is held without load for one hour (600 ° C) or two hours (700 ° C to 1100 ° C) for temperature compensation. Thereafter, the sample is loaded with a tensile force to maintain the desired strain rates, and the test begins.

The creep resistance of a material improves with increasing heat resistance. Therefore, the hot strength is also used to evaluate the creep resistance of the various materials.

The corrosion resistance at higher temperatures was determined in an oxidation test at 1000 ° C in air, the test was interrupted every 96 hours and the mass changes of the samples was determined by the oxidation. The samples were placed in the ceramic crucible in the experiment, so that possibly spalling oxide was collected and by weighing the crucible containing the oxides, the mass of the chipped oxide can be determined. The sum of the mass of the chipped oxide and the mass change of the samples corresponds to the gross mass change of the sample. The specific mass change is the mass change related to the surface of the samples. These are m _net for the specific net mass change, m _gross for the specific gross mass change, m _spall for the following designates specific mass change of the chipped oxides. The experiments were carried out on samples with about 5 mm thickness. 3 samples were removed from each batch, the values given are the mean values of these 3 samples.

Description of the properties

• eine gute Phasenstabilität
• eine gute Verarbeitbarkeit
• eine gute Korrosionsbeständigkeit an Luft, ähnlich der von Alloy 602CA (N06025)
• eine gute Warmfestigkeit / Kriechfestigkeit

The alloy according to the invention, in addition to excellent metal-dusting resistance, should at the same time have the following properties:

• a good phase stability
• a good processability
• good corrosion resistance in air, similar to Alloy 602CA (N06025)
• a good heat resistance / creep resistance

phase stability

In the system nickel-chromium-aluminum-iron with additions of Ti and / or Nb, various embrittling TCP phases can occur depending on the alloy contents, such as the Laves phases, sigma phases or the μ phases or the embrittling η phases or form ε-phases. (see, for. B. Ralf Bürgel, Handbook of High Temperature Materials, 3rd Edition, Vieweg Verlag, Wiesbaden, 2006, page 370 - 374 ). The calculation of the equilibrium phase components as a function of the temperature of z. For example, batch 111389 for N06690 (see Table 2 for typical compositions) shows computationally the formation of α-chromium with a low content of Ni and / or Fe (BCC phase in Figure 2) below 720 ° C (T _{s BCC} ) large proportions. However, this phase is difficult to form because it is very different analytically from the basic material. However, if the formation temperature T _{s BCC of} this phase is very high, then it may well occur, as z. In E. "Slevolden, JZ Albertsen, U. Fink," Tjeldbergodden methanol Plant: Metal Dusting Investigations, Corrosion / 2011, paper no. 11144 (Houston, TX: NACE 2011), p. 15 for a variant of Alloy 693 (US 06693) This phase is brittle and leads to an undesired embrittlement of the material Figure 3 and Figure 4 show the phase diagrams of the Alloy 693 variants (out US 4,882,125 Table 1) Alloy 3 or Alloy 10 from Table 2. Alloy 3 has a formation temperature T _{s BCC} of 1079 ° C, Alloy 10 of 639 ° C. In " E. Slevolden, JZ Albertsen. U. Fink, Tjeldbergodden Methanol Plant: Metal Dusting Investigations, "Corrosion / 2011, paper no. 11144 (Houston, TX: NACE 2011), p.15 "Although the exact analysis of the alloy in the case of α-chromium (BCC) does not appear, it is to be assumed that among the examples given in Table 2 for Alloy 693, in the analyzes which arithmetically have the highest formation temperatures T _{s BCC} (such as Alloy 10) can form α-chromium (BCC phase) in a corrected analysis (with reduced formation temperature T _{s BCC} ) was in " E. Slevolden, JZ Albertsen. U. Fink, Tjeldbergodden Methanol Plant: Metal Dusting Investigations, Corrosion / 2011, paper no. 11144 (Houston, TX: NACE 2011), p. 15 In order to avoid the occurrence of such an embrittling phase, in the case of the alloys according to the invention the formation temperature T _{s BCC should be} less than or equal to 939 ° C. - the lowest formation temperature T _{s BCC} under the examples of Alloy 693 in Table 2 (out US 4,88,125 Table 1).

$$\mathrm{Fp}=\mathrm{Cr}+\mathrm{0},\mathrm{272}*\mathrm{Fe}+\mathrm{2},\mathrm{36}*\mathrm{Al}+\mathrm{2},\mathrm{22}*\mathrm{Si}+\mathrm{2},\mathrm{48}*\mathrm{Ti}+\mathrm{0},\mathrm{374}*\mathrm{Mo}+\mathrm{0},\mathrm{538}*\mathrm{W}-\mathrm{11},\mathrm{8}*\mathrm{C}$$

Wobei Cr, Al, Fe, Si, Ti, Nb, Cu, Mo, W und C die Konzentration der betreffenden Elemente in Masse-% sind.This is especially the case if the following formula is true: $$\mathrm{fp}\le 39.9\mathrm{With}$$

$$\mathrm{fp}=\mathrm{Cr}+\mathrm{0}.\mathrm{272}*\mathrm{Fe}+\mathrm{2}.\mathrm{36}*\mathrm{al}+\mathrm{2}.\mathrm{22}*\mathrm{Si}+\mathrm{2}.\mathrm{48}*\mathrm{Ti}+\mathrm{0}.\mathrm{374}*\mathrm{Not\; a\; word}+\mathrm{0}.\mathrm{538}*\mathrm{W}-\mathrm{11}.\mathrm{8th}*\mathrm{C}$$

Wherein, Cr, Al, Fe, Si, Ti, Nb, Cu, Mo, W and C are the concentration of the respective elements in mass%.

Table 2 with the prior art alloys shows that Fp for Alloy 8, Alloy 3 and Alloy 2 is> 39.9 and for Alloy 10 is just 39.9. For all other alloys with T _{s BCC} <939 ° C Fp ≤ 39.9.

workability

By way of example, the formability is considered here for the processability.

An alloy can be hardened by several mechanisms so that it has a high heat resistance or creep resistance. Thus, the alloying of another element, depending on the element, causes a greater or lesser increase in strength (solid solution hardening). Far more effective is an increase in strength through fine particles or precipitates (particle hardening). This can be z. B. by the γ'-phase, which form with additions of Al and other elements, such as Ti, to a nickel alloy or by carbides which form by the addition of carbon to a chromium-containing nickel alloy ( see eg Ralf Bürgel, Handbuch der Hochtemperaturwerkstofftechnik, 3rd edition, Vieweg Verlag, Wiesbaden, 2006, pages 358 - 369 ).

Although the increase in the content of the γ'-phase-forming elements, or the C content, increases the hot strength, but increasingly affects the ductility, even in the solution-annealed state.

For a material that can be formed very easily, strains A5 in the tensile test at room temperature of ≥ 50%, but at least ≥ 45%, are aimed for.

$$\mathrm{Fa}=\mathrm{Cr}+\mathrm{6},\mathrm{15}*\mathrm{Nb}+\mathrm{20},\mathrm{4}*\mathrm{Ti}+\mathrm{201}*\mathrm{C}$$

wobei Cr, Nb, Ti und C die Konzentration der betreffenden Elemente in Masse-% sind.This is achieved in particular if the following relationship is fulfilled between the carbide-forming elements Cr, Nb, Ti and C: $$\mathrm{fa}\le 60\mathrm{With}$$

$$\mathrm{fa}=\mathrm{Cr}+\mathrm{6}.\mathrm{15}*\mathrm{Nb}+\mathrm{20}.\mathrm{4}*\mathrm{Ti}+\mathrm{201}*\mathrm{C}$$

wherein Cr, Nb, Ti and C are the concentration of the respective elements in mass%.

Temperature strength / creep

$$\mathrm{800}\mathrm{°C}:{\mathrm{Dehngrenze\; R}}_{\mathrm{p}\mathrm{0},\mathrm{2}}>\mathrm{130}\mathrm{MPA};{\mathrm{Zugfestigkeit\; R}}_{\mathrm{m}}>135\mathrm{MPA}$$

At the same time, the yield strength, or the tensile strength, at higher temperatures should at least reach the values of Alloy 601 (see Table 4). $$\mathrm{600}\mathrm{°\; C}:{\mathrm{Yield\; <figure-callout\; id="0"\; label="point\; R\; p"\; filenames="imgf0002.png"\; state="\{\{state\}\}">point\; R\; </figure-callout>}}_{\mathrm{p}}>\mathrm{150}\mathrm{MPA};{\mathrm{Tensile\; strength\; R}}_{\mathrm{m}}>\mathrm{500}\mathrm{<figure-callout\; id="800"\; label="MPA"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">MPA</figure-callout>}$$

$$\mathrm{800}\mathrm{°\; C}:{\mathrm{Yield\; <figure-callout\; id="0"\; label="point\; R\; p"\; filenames="imgf0002.png"\; state="\{\{state\}\}">point\; R\; </figure-callout>}}_{\mathrm{p}}>\mathrm{130}\mathrm{MPA};{\mathrm{Tensile\; strength\; R}}_{\mathrm{m}}>135\mathrm{MPA}$$

$$\mathrm{800}\mathrm{°C}:{\mathrm{Dehngrenze\; R}}_{\mathrm{p}\mathrm{0},\mathrm{2}}>\mathrm{180}\mathrm{MPA};{\mathrm{Zugfestigkeit\; R}}_{\mathrm{m}}>\mathrm{190}\mathrm{MPA}$$

It would be desirable for the yield strength or tensile strength to be in the range of Alloy602 CA (see Table 4). At least 3 of the 4 following relations should be fulfilled: $$\mathrm{600}\mathrm{°\; C}:{\mathrm{Yield\; <figure-callout\; id="0"\; label="point\; R\; p"\; filenames="imgf0002.png"\; state="\{\{state\}\}">point\; R\; </figure-callout>}}_{\mathrm{p}}>\mathrm{230}\mathrm{MPA};{\mathrm{Tensile\; strength\; R}}_{\mathrm{m}}>\mathrm{550}\mathrm{<figure-callout\; id="800"\; label="MPA"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">MPA</figure-callout>}$$

$$\mathrm{800}\mathrm{°\; C}:{\mathrm{Yield\; <figure-callout\; id="0"\; label="point\; R\; p"\; filenames="imgf0002.png"\; state="\{\{state\}\}">point\; R\; </figure-callout>}}_{\mathrm{p}}>\mathrm{180}\mathrm{MPA};{\mathrm{Tensile\; strength\; R}}_{\mathrm{m}}>\mathrm{190}\mathrm{MPA}$$

$$\mathrm{Fk}=\mathrm{Cr}+\mathrm{19}*\mathrm{Ti}+\mathrm{34},\mathrm{3}*\mathrm{Nb}+\mathrm{10},\mathrm{2}*\mathrm{Al}+\mathrm{12},\mathrm{5}*\mathrm{Si}+\mathrm{98}*\mathrm{C}+\mathrm{2245}*\mathrm{B}$$

wobei Cr, Ti, Nb, Al, Si, C und B die Konzentration der betreffenden Elemente in Masse-% sind.This is achieved in particular if the following relationship between the main hardening elements is fulfilled: $$\mathrm{Fk}\ge 45\mathrm{With}$$

$$\mathrm{Fk}=\mathrm{Cr}+\mathrm{19}*\mathrm{Ti}+\mathrm{34}.\mathrm{3}*\mathrm{Nb}+\mathrm{10}.\mathrm{2}*\mathrm{al}+\mathrm{12}.\mathrm{5}*\mathrm{Si}+\mathrm{98}*\mathrm{C}+\mathrm{2245}*\mathrm{B}$$

wherein Cr, Ti, Nb, Al, Si, C and B are the concentration of the respective elements in mass%.

• Die erfindungsgemäße Legierung soll eine gute Korrosionsbeständigkeit an Luft, ähnlich der von Alloy 602CA (N06025), haben.

Corrosion resistance:

• The alloy according to the invention is said to have good corrosion resistance in air, similar to Alloy 602CA (N06025).

Examples: production:

Tables 3a and 3b show the analyzes of laboratory-scale molten batches along with some prior art large scale molten batches of Alloy 602CA (N06025) used for comparison. Alloy 690 (N06690), Alloy 601 (N06601). The prior art batches are marked with a T, those of the invention with an E. The batches marked on the laboratory scale are marked with an L, the large-scale blown batches with a G.

The blocks of laboratory-scale molten alloys in Tables 3a and b were annealed between 900 ° C and 1270 ° C for 8 hours and hot rolled and further intermediate anneals between 900 ° C and 1270 ° C for 0.1 to 1 hour Final thickness of 13 mm or 6 mm hot rolled. The sheets produced in this way were solution-annealed between 900 ° C. and 1270 ° C. for 1 h. From these sheets, the samples required for the measurements were produced.

In the case of the large-scale smelted alloys, a sample was taken from the large-scale production of an industrially manufactured sheet with a suitable thickness. From these sheets, the samples required for the measurements were produced.

All alloy variants typically had a particle size of 70 to 300 μm.

• Metal Dusting Beständigkeit
• Phasenstabilität
• Umformbarkeit anhand des Zugversuches bei Raumtemperatur
• Warmfestigkeit / Kriechbeständigkeit mit Hilfe von Warmzugversuchen
• Korrosionsbeständigkeit mit Hilfe eines Oxidationstests

For the example batches in Tables 3a and b, the following properties are compared:

• Metal dusting resistance
• phase stability
• Formability based on the tensile test at room temperature
• Hot strength / creep resistance with the help of hot tensile tests
• Corrosion resistance with the help of an oxidation test

For the batches 2297 to 2308 and 250060 to 250149 melted on a laboratory scale, but especially for the batches according to the invention marked with E (2301, 250129, 250132, 250133, 250134, 250137, 240138, 250147, 250148), the formula (2a) is Al + Cr ≥ 28 fulfilled. They thus meet the demand that has been placed on the metal dusting resistance.

For the selected prior art alloys in Table 2 and all laboratory lots (Tables 3a and 3b), therefore, the phase diagrams were calculated and the formation temperature T _{s BCC is} plotted in Tables 2 and 3a. For the compositions in Tables 2 and 3a and b also the value of Fp according to formula 4a was calculated. Fp is greater, the larger the formation temperature T _{s BCC} . All examples of N06693 with a higher formation temperature T _{s BCC} than that of Alloy 10 have a Fp> 39.9. The requirement Fp ≦ 39.9 (formula 3a) is thus a good criterion for obtaining a sufficient phase stability in the case of an alloy. All laboratory batches in Tables 3a and b fulfill the criterion Fp ≤ 39.9.

Table 4 shows the yield strength R _p0.2 , the tensile strength R _m and the elongation A ₅ for room temperature (RT) and for 600 ° C, furthermore the tensile strength R _m for 800 ° C. In addition, the values for Fa and Fk are entered.

Example batches 156817 and 160483 of the prior art alloy Alloy 602 CA have in Table 4 a relatively low elongation A5 at room temperature of 36 and 42%, respectively, which are below the requirements for good formability. Fa is> 60, which is above the range that indicates good formability. All inventive alloys (E) show an elongation> 50%. They thus fulfill the requirements. Fa is <60 for all alloys according to the invention. They are therefore in the range of good formability. The elongation is particularly high when Fa is comparatively small.

Example Example 156658 of the prior art Alloy 601 in Table 4 is an example of the minimum requirements for yield strength and tensile strength at 600 ° C and 800 ° C, respectively. Example lots 156817 and 160483 of the prior art Alloy 602 CA alloy on the other hand are examples of very good values of yield strength and tensile strength at 600 ° C and 800 ° C, respectively. Alloy 601 represents a material that meets the minimum requirements Creep resistance described in Relation 9a to 9d shows Alloy 602 CA a material exhibiting excellent creep strength described in Relation 10a to 10d. The value for Fk is significantly greater for both alloys than 45 and for Alloy 602 CA additionally significantly higher than the value of Alloy 601, reflecting the increased strength values of Alloy 602 CA. The alloys (E) according to the invention all exhibit a yield strength and tensile strength at 600 ° C. or 800 ° C. in the region or significantly above that of Alloy 601, ie they have fulfilled the relations 9a to 9d. They are in the range of the values of Alloy 602 CA and also meet the desirable requirements, ie 3 of the 4 relations 10a to 10d. Also for all alloys according to the invention in the examples in Table 4, Fk is greater than 45, and even most greater than 54, and thus in the range characterized by good heat resistance or creep resistance. Among the laboratory batches not according to the invention, the batches 2297 and 2300 are an example that the relations 9a to 9d are not fulfilled and also a Fk <45 is given.

Table 5 shows the specific mass changes after an oxidation test at 1100 ° C in air after 11 cycles of 96 h, for a total of 1056 h. Given in Table 5 are the specific gross mass change, the net specific mass change and the specific mass change of the chipped oxides after 1056 h. The example batches of the prior art alloys Alloy 601 and Alloy 690 showed a significantly higher gross mass change than Alloy 602 CA, with that of Alloy 601 again being significantly larger than that of Alloy 690. Both form a chromium oxide layer that grows faster than an aluminum oxide layer. Alloy 601 still contains about 1.3% Al. This content is too low to form even if partially closed aluminum oxide layer, which is why the aluminum in the interior of the metallic material below the oxide layer oxidizes (internal oxidation), which causes an increased compared to Alloy 690 mass increase. Alloy 602 CA has approx. 2.3% aluminum. This can be below the Chromoxidschicht form an at least partially closed aluminum oxide layer. This noticeably reduces the growth of the oxide layer and thus also the specific mass increase. All alloys (E) according to the invention contain at least 2% aluminum and thus have a similarly low or lower gross mass increase than Alloy 602 CA. Also, all of the alloys of the invention, similar to the example batches of Alloy 602 CA, exhibit flaking in the area of measurement accuracy, while Alloy 601 and Alloy 690 show large flaking.

• Zu geringe Cr-Gehalte bedeuten, dass die Cr-Konzentration an der Grenzfläche Oxid-Metall beim Einsatz der Legierung in einer korrosiven Atmosphäre sehr schnell unter die kritische Grenze sinkt, so dass sich bei einer Beschädigung der Oxidschicht keine geschlossene reine Chromoxidschicht mehr bilden kann, sondern sich auch andere weniger schützende Oxide bilden können. Deshalb ist 24 % Cr die untere Grenze für Chrom. Zu hohe Cr-Gehalte verschlechtern die Phasenstabilität der Legierung insbesondere bei den hohen Aluminiumgehalten von ≥ 1,8 %. Deshalb ist 33 % Cr als obere Grenze anzusehen.

The claimed limits for the alloy "E" according to the invention can therefore be explained in detail as follows:

• Too low Cr contents mean that the Cr concentration at the oxide-metal interface falls very rapidly below the critical limit when the alloy is used in a corrosive atmosphere, so that when the oxide layer is damaged, a closed, pure chromium oxide layer can no longer form. but also other less protective oxides can form. Therefore, 24% Cr is the lower limit for chromium. Too high Cr contents deteriorate the phase stability of the alloy, in particular with the high aluminum contents of ≥ 1.8%. Therefore, 33% Cr is considered the upper limit.

The formation of an aluminum oxide layer below the chromium oxide layer reduces the oxidation rate. Below 1.8% Al, the forming aluminum oxide layer is too patchy to fully develop its effect. Excessive Al contents impair the processability of the alloy. Therefore, an AI content of 4.0% is the upper limit.

The cost of the alloy increases with the reduction of the iron content. Below 0.1%, the costs increase disproportionately, since special starting material must be used. For this reason, 0.1% Fe is the lower limit for cost reasons. As the iron content increases, the phase stability (formation of embrittling phases) decreases, especially at high levels Chromium and aluminum contents. Therefore, 7% Fe is a useful upper limit to ensure the phase stability of the alloy of the invention.

Si is needed in the production of the alloy. It is therefore necessary a minimum content of 0.001%. Too high levels, in turn, affect processability and phase stability, especially at high levels of aluminum and chromium. The Si content is therefore limited to 0.50%.

A minimum content of 0.005% Mn is required to improve processability. Manganese is limited to 2.0% because this element reduces oxidation resistance.

Titanium increases the high-temperature strength. From 0.60%, the oxidation behavior can be degraded, which is why 0.60% is the maximum value.

Already very low Mg and / or Ca contents improve the processing by the setting of sulfur, whereby the occurrence of low-melting NiS Eutektika is avoided. For Mg and or Ca, therefore, a minimum content of 0.0002% is required. If the contents are too high, intermetallic Ni-Mg phases or Ni-Ca phases may occur, which again significantly impair processability. The Mg and / or Ca content is therefore limited to a maximum of 0.05%.

A minimum content of 0.005% C is required for good creep resistance. C is limited to a maximum of 0.12%, since this element reduces the processability by the excessive formation of primary carbides from this content.

A minimum content of 0.001% N is required, which improves the processability of the material. N is limited to a maximum of 0.05%, since this element reduces the processability by forming coarse carbonitrides. The oxygen content must be ≤ 0.020% to ensure the manufacturability of the alloy. Too low an oxygen content increases the costs. The oxygen content is therefore ≥ 0.0001%.

The content of phosphorus should be less than or equal to 0.030%, since this surfactant affects the oxidation resistance. A too low P content increases the costs. The P content is therefore ≥ 0.001%.

The levels of sulfur should be adjusted as low as possible, since this surfactant affects the oxidation resistance. It will therefore max. 0.010% S set,

Molybdenum is reduced to max. 2.0% limited as this element reduces oxidation resistance.

Tungsten is limited to max. 2.0% limited as this element also reduces oxidation resistance.

wobei Cr und Al die Konzentration der betreffenden Elemente in Masse-% sind. Nur dann ist der Gehalt an oxidbildenden Elementen hoch genug, um eine ausreichende Metal Dusting Beständig zu gewährleisten.The following relationship between Cr and Al must be satisfied for sufficient resistance to metal dusting: $$\mathrm{Cr}+\mathrm{al}\ge 28$$

where Cr and Al are the concentration of the respective elements in mass%. Only then is the content of oxide-forming elements high enough to ensure adequate metal dusting resistance.

$$\mathrm{Fp}=\mathrm{Cr}+\mathrm{0},\mathrm{272}*\mathrm{Fe}+\mathrm{2},\mathrm{36}*\mathrm{Al}+\mathrm{2},\mathrm{22}*\mathrm{Si}+\mathrm{2},\mathrm{48}*\mathrm{Ti}+\mathrm{0},\mathrm{374}*\mathrm{Mo}+\mathrm{0},\mathrm{538}*\mathrm{W}-\mathrm{11},\mathrm{8}*\mathrm{C}$$

wobei Cr, Fe, Al, Si, Ti, Mo, W und C die Konzentration der betreffenden Elemente in Masse-% sind. Die Grenzen für Fp und die mögliche Einbeziehung weiterer Elemente wurden im vorangegangenen Text ausführlich begründet.In addition, the following relationship must be satisfied for sufficient phase stability: $$\mathrm{fp}\le 39.9\mathrm{With}$$

$$\mathrm{fp}=\mathrm{Cr}+\mathrm{0}.\mathrm{272}*\mathrm{Fe}+\mathrm{2}.\mathrm{36}*\mathrm{al}+\mathrm{2}.\mathrm{22}*\mathrm{Si}+\mathrm{2}.\mathrm{48}*\mathrm{Ti}+\mathrm{0}.\mathrm{374}*\mathrm{Not\; a\; word}+\mathrm{0}.\mathrm{538}*\mathrm{W}-\mathrm{11}.\mathrm{8th}*\mathrm{C}$$

wherein Cr, Fe, Al, Si, Ti, Mo, W and C are the concentration of the respective elements in mass%. The limits for Fp and the possible inclusion of further elements have been explained in detail in the previous text.

If necessary, with additions of oxygen-affine elements, the oxidation resistance can be further improved. They do this by incorporating them into the oxide layer and blocking the diffusion paths of the oxygen there on the grain boundaries.

A minimum content of 0.01% Y is necessary to obtain the oxidation resistance-enhancing effect of Y. The upper limit is set at 0.20% for cost reasons.

A minimum content of 0.001% La is necessary to obtain the oxidation resistance enhancing effect of La. The upper limit is set at 0.20% for cost reasons.

A minimum content of 0.001% Ce is necessary to obtain the oxidation resistance-enhancing effect of Ce. The upper limit is set at 0.20% for cost reasons.

A minimum content of 0.001% cerium mischmetal is necessary to obtain the oxidation resistance enhancing effect of cerium mischmetal. The upper limit is set at 0.20% for cost reasons.

If necessary, niobium can be added, as niobium also increases the high-temperature strength. Higher levels increase costs very much. The upper limit is therefore set at 1.10%.

If necessary, the alloy may also contain tantalum, since tantalum also increases high-temperature strength. Higher levels increase costs very much.

The upper limit is therefore set at 0.60%. A minimum level of 0.001% is required to have an effect.

If necessary, the alloy can also be given Zr. A minimum content of 0.01% Zr is necessary to obtain the high-temperature strength and oxidation resistance-enhancing effect of Zr. The upper limit is set at 0.20% Zr for cost reasons.

If necessary, Zr can be wholly or partially replaced by Hf, since this element, such as Zr, also increases high-temperature strength and oxidation resistance. Replacement is possible from 0.001%. The upper limit is set at 0.20% Hf for cost reasons.

If necessary, boron may be added to the alloy because boron improves creep resistance. Therefore, a content of at least 0.0001% should be present. At the same time, this surfactant deteriorates the oxidation resistance. It will therefore max. 0.008% Boron set.

Cobalt can be contained in this alloy up to 5.0%. Higher contents considerably reduce the oxidation resistance.

Copper is heated to max. 0.5% limited as this element reduces the oxidation resistance.

Vanadium is reduced to max. 0.5% limited as this element also reduces oxidation resistance.

Pb is set to max. 0.002% limited because this element reduces the oxidation resistance. The same applies to Zn and Sn.

$$\mathrm{Fa}=\mathrm{Cr}+\mathrm{20},\mathrm{4}*\mathrm{Ti}+\mathrm{201}*\mathrm{C}$$

wobei Cr, Ti und C die Konzentration der betreffenden Elemente in Masse-% sind. Die Grenzen für Fa und die mögliche Einbeziehung weiterer Elemente wurden im vorangegangenen Text ausführlich begründet.Furthermore, optionally, the following relationship of carbide-forming elements Cr, Ti and C can be satisfied, which describes a particularly good processability: $$\mathrm{fa}\le 60\mathrm{With}$$

$$\mathrm{fa}=\mathrm{Cr}+\mathrm{20}.\mathrm{4}*\mathrm{Ti}+\mathrm{201}*\mathrm{C}$$

where Cr, Ti and C are the concentration of the respective elements in mass%. The limits for Fa and the possible inclusion of other elements have been extensively explained in the previous text.

$$\mathrm{Fk}=\mathrm{Cr}+19*\mathrm{Ti}+10,2*\mathrm{Al}+12,5*\mathrm{Si}+98*\mathrm{C}$$

wobei Cr, Ti, Al, Si und C die Konzentration der betreffenden Elemente in Masse-% sind. Die Grenzen für Fa und die mögliche Einbeziehung weiterer Elemente wurden im vorangegangenen Text ausführlich begründet.

Tabelle 3b: Zusammensetzung der Laborchargen, Teil 2. Alle Angaben in Masse-% (Für alle Legierungen gilt: Pb: max. 0,002 %,Zn: max. 0,002 %,Sn: max. 0,002 %) (Bedeutung von T, E, G, L, siehe Tabelle 3a) Name Chg S P Mg Ca V Zr Co Y La_ B Hf Ta Ce O T G Alloy602CA 156817 0,002 0,005 0,004 0,001 0,03 0,08 0,05 0,060 - 0,003 - - - 0,001 T G Alloy602CA 160483 <0,002 0,007 0,010 0,002 - 0,09 0,04 0,070 - 0,003 - - - 0,001 T G Alloy601 156656 0,002 0,008 0,012 <0,01 0,03 0,015 0,04 - - 0,001 - - - 0,0001 T G Alloy690 80116 0,002 0,006 0,030 0,0009 - <0,002 0,02 - - 0,002 - - - 0,0005 T G Alloy690 111389 0,002 0,005 <0,001 0,0005 - - 0,01 - - - - - - 0,001 L Cr30Al1La 2297 0,004 0,003 0,015 <0,01 <0,01 <0,002 - <0,001 0,062 <0,001 <0,001 <0,005 0,001 0,0001 L Cr30Al1LaT 2300 0,003 0,002 0,014 <0,01 <0,01 <0,002 <0,001 <0,001 0,051 <0,001 <0,001 <0,005 0,001 0,0001 L Cr30Al1TiLa 2298 0,004 0,002 0,016 <0,01 <0,01 <0,002 <0,001 <0,001 0,058 <0,001 <0,001 <0,005 0,001 0,002 L Cr30Al1TiNbLa 2308 0,002 0,002 0,014 <0,01 <0,01 <0,002 - <0,001 0,093 <0,001 <0,001 <0,005 0,001 0,002 L Cr30Al1CLaTi 2299 0,003 0,002 0,015 <0,01 <0,01 <0,002 <0,001 <0,001 0,064 <0,001 <0,001 <0,005 0,001 0,002 L Cr30Al1CLa 2302 0,003 0,002 0,013 <0,01 <0,01 <0,002 0,001 <0,001 0,057 <0,001 <0,001 <0,005 0,001 0,0001 E L Cr30Al2La 2301 0,003 0,002 0,015 <0,01 <0,01 <0,002 <0,001 <0,001 0,058 <0,001 <0,001 <0,005 0,001 0,002 L Cr30Al1Ti 250060 0,003 0,002 0,009 <0,01 <0,01 <0,002 <0,001 <0,001 <0,001 <0,001 <0,001 <0,005 <0,001 0,003 L Cr30Al1Ti 250063 0,003 0,003 0,012 <0,01 <0,01 <0,002 <0,001 <0,001 <0,001 <0,001 <0,001 <0,005 <0,001 0,003 L Cr30Al1TiNb 250066 0,002 0,002 0,012 <0,01 <0,01 <0,002 <0,001 <0,001 <0,001 <0,001 <0,001 <0,005 <0,001 0,004 L Cr30Al1TiNb 250065 0,002 0,002 0,012 <0,01 <0,01 <0,002 <0,001 <0,001 <0,001 <0,001 <0,001 <0,005 <0,001 0,005 L Cr30Al1TiNbZr 250067 0,003 0,002 0,010 <0,01 <0,01 0,069 <0,001 <0,001 <0,001 <0,001 <0,001 <0,005 <0,001 0,003 L Cr30Al1TiNb 250068 0,002 <0,002 0,010 <0,01 <0,01 <0,002 <0,001 <0,001 <0,001 <0,001 <0,001 <0,005 <0,001 0,004 E L Cr28Al2 250129 0,004 0,003 0,011 0,0002 <0,01 <0,002 - - - <0,0005 - - - 0,001 E L Cr28Al2Y 250130 0,003 0,003 0,013 <0,0002 <0,01 <0,002 - 0,063 - <0,0005 - - - 0,001 E L Cr28Al2YC1 250132 0,003 0,004 0,009 0,0012 0,01 0,003 <0,01 0,07 - 0,001 - - - 0,001 E L Cr28Al2Nb.5C1 250133 0,005 0,003 0,009 0,0012 <0,01 0,004 0,01 0,01 - - - - - 0,001 E L Cr28Al2Nb.5C1 250148 0,004 0,004 0,010 0,0005 0,01 - <0,01 <0,01 - - - - - 0,003 E L Cr28Al2Nb1C1 250134 0,006 0,002 0,009 0,0009 <0,01 0,006 0,01 0,01 - <0,0005 - - - 0,003 E L Cr28Al2Nb1C1 250147 0,002 0,002 0,010 0,0005 <0,01 0,01 0,01 0,01 - 0,0012 - - - 0,001 E L Cr28Al2Nb1C1Y 250149 0,004 0,005 0,013 <0,0005 <0,01 0,006 <0,01 0,08 - 0,0012 - - - 0,002 E L Cr28Al2TiC1 250137 0,005 0,004 0,008 0,0002 <0,01 0,004 <0,01 <0,01 - 0,0012 - - - 0,001 E L Cr28Al2TiC1 250138 0,005 0,004 0,010 0,0002 <0,01 0,003 0,01 <0,01 - 0,0012 - - - 0,004 Tabelle 4: Ergebnisse der Zugversuche bei Raumtemperatur (RT), 600 °C und 800°C. Die Umformgeschwindigkeit betrug bei R _p0,2 8,33 10^-5 1/s (0,5%/min) und bei R_m 8,33 10^-4 1/s (5%/min); KG = Korngröße. Name Chg KG in µm R_p0,2 in MPa RT R_m in MPa RT A₅ in % RT R_p0,2 in MPa 600°C R_m in MPa 600°C A₅ in % 600°C R_p0,2 in MPa 800°C R_m in MPa 800°C Fa Fk T Alloy 602 CA 156817 76 292 699 36 256 578 41 186 198 63,0 76,9 T Alloy 602 CA 160483 76 340 721 42 254 699 69 186 197 62,2 79,6 T Alloy601 156656 136 238 645 53 154 509 54 133 136 43,3 56,3 T Aloy 690 80116 92 279 641 56 195 469 48 135 154 36,2 41,6 T Alloy 690 111389 72 285 630 50 188 465 51 - - 36,8 43,6 Cr30Al1La 2297 233 221 637 67 131 460 61 134 167 33,5 43,4 Cr30Al1LaT 2300 205 229 650 71 131 469 65 132 160 33,9 46,3 Cr30Al1TiLa 2298 94 351 704 59 228 490 31 149 161 39,7 51,5 Cr30Al1TiNbLa 2308 90 288 683 55 200 508 39 174 181 41,6 61,0 Cr30Al1CLaTi 2299 253 258 661 62 212 475 59 181 185 42,3 50,0 Cr30Al1CLa 2302 212 353 673 59 233 480 59 189 194 40,0 52,9 E Cr30Al2La 2301 155 375 716 66 298 504 49 275 277 33,2 55,6 Cr30Al1Ti 250060 114 252 662 67 183 509 62 143 154 39,3 50,4 Cr30Al1Ti 250063 118 252 659 70 178 510 57 148 152 39,6 52,9 Cr30Al1TiNb 250066 121 240 666 67 186 498 66 245 255 41,4 63,6 Cr30Al1TiNb 250065 132 285 685 61 213 521 58 264 265 41,8 64,0 Cr30Al1TiNbZr 250067 112 287 692 67 227 532 65 280 280 41,6 64,2 Cr30Al1TiNb 250068 174 261 666 69 205 498 65 297 336 44,9 83,2 E Cr28Al2 250129 269 334 674 66 - - - 191 224 31,8 56,8 E Cr28Al2Y 250130 167 322 693 63 252 522 53 220 244 32,6 57,9 E Cr28Al2YC1 250132 189 301 669 65 - - - 226 226 40,2 64,0 E Cr28Al2Nb.5C1 250133 351 399 725 57 334 522 33 285 353 40,8 78,9 E Cr28Al2Nb.5C1 250148 365 353 704 60 284 523 58 259 344 41,2 79,5 E Cr28Al2Nb1C1 250134 384 448 794 59 410 579 28 343 377 44,4 99,4 E Cr28Al2Nb1 C1 250147 350 372 731 57 306 547 49 309 384 43,0 89,1 E Cr28Al2Nb1C1Y 250149 298 415 784 53 339 528 27 340 400 45,1 99,2 E Cr28Al2TiC1 250137 142 379 745 59 327 542 29 311 314 44,0 70,4 E Cr28Al2TiC1 250138 224 348 705 61 278 510 46 247 296 42,2 66,5 Tabelle 5: Ergebnisse der Oxidationsversuche bei 1000 °C an Luft nach 1056 h. Name Chg Versuch Nr m_brutto in g/m² m_netto in g/m² uum_spall in g/m² T Alloy 602 CA 160483 412 8,66 7,83 0,82 T Alloy 602 CA 160483 425 5,48 5,65 -0,18 T Alloy 601 156125 403 51,47 38,73 12,74 T Alloy 690 111389 412 23,61 7,02 16,59 T Alloy 690 111389 421 30,44 -5,70 36,14 T Alloy 690 111389 425 28,41 -0,68 29,09 Cr30Al1La 2297 412 36,08 -7,25 43,33 Cr30Al1LaT 2300 412 41,38 -2,48 43,86 Cr30Al1TiLa 2298 412 49,02 -30,59 79,61 Cr30Al1TiNbLa 2306 412 40,43 16,23 24,20 Cr30Al1CLaTi 2308 412 42,93 -15,54 58,47 Cr30Al1CLa 2299 412 30,51 0,08 30,44 Cr30Al2La 2302 412 27,25 9,57 17,68 E Cr30Al1Ti 2301 412 8,43 6,74 1,69 Cr30Al1Ti 250060 421 43,30 -19,88 63,17 Cr30Al1TiNb 250063 421 32,81 -22,15 54,96 Cr30Al1TiNb 250066 421 26,93 -16,35 43,28 Cr30Al1TiNbZr 250065 421 25,85 -24,27 50,12 Cr30Al1TiNb 250067 421 41,59 -15,56 57,16 Cr28Al2 250068 421 42,69 -39,26 81,95 E Cr28Al2Y 250129 425 3,72 3,55 0,16 E Cr28Al2YC1 250130 425 4,68 4,90 -0,23 E Cr28Al2Nb.5C1 250132 425 3,94 5,01 -1,07 E Cr28Al2Nb.5C1 250133 425 2,56 3,98 -1,42 E Cr28Al2Nb1C1 250148 425 3,15 3,21 -0,07 E Cr28Al2Nb1C1 250134 425 3,34 4,23 -0,89 E Cr28Al2Nb1C1Y 250147 425 2,72 2,62 0,10 E Cr28Al2TiC1 250149 425 3,44 3,84 -0,40 E Cr28Al2TiC1 250137 425 3,62 4,24 -0,62 E Cr30Al1La 250138 425 3,87 4,28 -0,41 Furthermore, optionally, the following relationship with respect to the strength-enhancing elements can be satisfied, which describes a particularly good hot strength or creep resistance: $$\mathrm{Fk}\ge 45\mathrm{With}$$

$$\mathrm{Fk}=\mathrm{Cr}+19*\mathrm{Ti}+10.2*\mathrm{al}+12.5*\mathrm{Si}+98*\mathrm{C}$$

wherein Cr, Ti, Al, Si and C are the concentration of the respective elements in mass%. The limits for Fa and the possible inclusion of other elements have been extensively explained in the previous text.

Table 3b: Composition of laboratory batches, part 2. All data in mass% (For all alloys applies: Pb: max 0.002%, Zn: max 0.002%, Sn: max 0.002%) (meaning of T, E, G, L, see Table 3a) Surname Chg S P mg Ca V Zr Co Y LA_ B Hf Ta Ce O T G Alloy602CA 156817 0,002 0.005 0,004 0.001 0.03 0.08 0.05 0,060 - 0,003 - - - 0.001 T G Alloy602CA 160483 <0.002 0,007 0,010 0,002 - 0.09 0.04 0,070 - 0,003 - - - 0.001 T G Alloy601 156656 0,002 0,008 0,012 <0.01 0.03 0,015 0.04 - - 0.001 - - - 0.0001 T G Alloy690 80116 0,002 0,006 0,030 0.0009 - <0.002 0.02 - - 0,002 - - - 0.0005 T G Alloy690 111389 0,002 0.005 <0.001 0.0005 - - 0.01 - - - - - - 0.001 L Cr30Al1La 2297 0,004 0,003 0,015 <0.01 <0.01 <0.002 - <0.001 0.062 <0.001 <0.001 <0.005 0.001 0.0001 L Cr30Al1LaT 2300 0,003 0,002 0,014 <0.01 <0.01 <0.002 <0.001 <0.001 0,051 <0.001 <0.001 <0.005 0.001 0.0001 L Cr30Al1TiLa 2298 0,004 0,002 0.016 <0.01 <0.01 <0.002 <0.001 <0.001 0.058 <0.001 <0.001 <0.005 0.001 0,002 L Cr30Al1TiNbLa 2308 0,002 0,002 0,014 <0.01 <0.01 <0.002 - <0.001 0.093 <0.001 <0.001 <0.005 0.001 0,002 L Cr30Al1CLaTi 2299 0,003 0,002 0,015 <0.01 <0.01 <0.002 <0.001 <0.001 0.064 <0.001 <0.001 <0.005 0.001 0,002 L Cr30Al1CLa 2302 0,003 0,002 0,013 <0.01 <0.01 <0.002 0.001 <0.001 0.057 <0.001 <0.001 <0.005 0.001 0.0001 e L Cr30Al2La 2301 0,003 0,002 0,015 <0.01 <0.01 <0.002 <0.001 <0.001 0.058 <0.001 <0.001 <0.005 0.001 0,002 L Cr30Al1Ti 250060 0,003 0,002 0.009 <0.01 <0.01 <0.002 <0.001 <0.001 <0.001 <0.001 <0.001 <0.005 <0.001 0,003 L Cr30Al1Ti 250063 0,003 0,003 0,012 <0.01 <0.01 <0.002 <0.001 <0.001 <0.001 <0.001 <0.001 <0.005 <0.001 0,003 L Cr30Al1TiNb 250066 0,002 0,002 0,012 <0.01 <0.01 <0.002 <0.001 <0.001 <0.001 <0.001 <0.001 <0.005 <0.001 0,004 L Cr30Al1TiNb 250065 0,002 0,002 0,012 <0.01 <0.01 <0.002 <0.001 <0.001 <0.001 <0.001 <0.001 <0.005 <0.001 0.005 L Cr30Al1TiNbZr 250067 0,003 0,002 0,010 <0.01 <0.01 0,069 <0.001 <0.001 <0.001 <0.001 <0.001 <0.005 <0.001 0,003 L Cr30Al1TiNb 250068 0,002 <0.002 0,010 <0.01 <0.01 <0.002 <0.001 <0.001 <0.001 <0.001 <0.001 <0.005 <0.001 0,004 e L Cr28Al2 250129 0,004 0,003 0.011 0.0002 <0.01 <0.002 - - - <0.0005 - - - 0.001 e L Cr28Al2Y 250130 0,003 0,003 0,013 <0.0002 <0.01 <0.002 - 0.063 - <0.0005 - - - 0.001 e L Cr28Al2YC1 250132 0,003 0,004 0.009 0.0012 0.01 0,003 <0.01 0.07 - 0.001 - - - 0.001 e L Cr28Al2Nb.5C1 250133 0.005 0,003 0.009 0.0012 <0.01 0,004 0.01 0.01 - - - - - 0.001 e L Cr28Al2Nb.5C1 250148 0,004 0,004 0,010 0.0005 0.01 - <0.01 <0.01 - - - - - 0,003 e L Cr28Al2Nb1C1 250134 0,006 0,002 0.009 0.0009 <0.01 0,006 0.01 0.01 - <0.0005 - - - 0,003 e L Cr28Al2Nb1C1 250147 0,002 0,002 0,010 0.0005 <0.01 0.01 0.01 0.01 - 0.0012 - - - 0.001 e L Cr28Al2Nb1C1Y 250149 0,004 0.005 0,013 <0.0005 <0.01 0,006 <0.01 0.08 - 0.0012 - - - 0,002 e L Cr28Al2TiC1 250137 0.005 0,004 0,008 0.0002 <0.01 0,004 <0.01 <0.01 - 0.0012 - - - 0.001 e L Cr28Al2TiC1 250138 0.005 0,004 0,010 0.0002 <0.01 0,003 0.01 <0.01 - 0.0012 - - - 0,004 Surname Chg KG in μm R _p0.2 in MPa RT R _m in MPa RT A ₅ in% RT R _p0.2 in MPa 600 ° C R _m in MPa 600 ° C A ₅ in% 600 ° C R _p0.2 in MPa 800 ° C R _m in MPa 800 ° C fa Fk T Alloy 602 CA 156817 76 292 699 36 256 578 41 186 198 63.0 76.9 T Alloy 602 CA 160483 76 340 721 42 254 699 69 186 197 62.2 79.6 T Alloy601 156656 136 238 645 53 154 509 54 133 136 43.3 56.3 T Aloy 690 80116 92 279 641 56 195 469 48 135 154 36.2 41.6 T Alloy 690 111389 72 285 630 50 188 465 51 - - 36.8 43.6 Cr30Al1La 2297 233 221 637 67 131 460 61 134 167 33.5 43.4 Cr30Al1LaT 2300 205 229 650 71 131 469 65 132 160 33.9 46.3 Cr30Al1TiLa 2298 94 351 704 59 228 490 31 149 161 39.7 51.5 Cr30Al1TiNbLa 2308 90 288 683 55 200 508 39 174 181 41.6 61.0 Cr30Al1CLaTi 2299 253 258 661 62 212 475 59 181 185 42.3 50.0 Cr30Al1CLa 2302 212 353 673 59 233 480 59 189 194 40.0 52.9 e Cr30Al2La 2301 155 375 716 66 298 504 49 275 277 33.2 55.6 Cr30Al1Ti 250060 114 252 662 67 183 509 62 143 154 39.3 50.4 Cr30Al1Ti 250063 118 252 659 70 178 510 57 148 152 39.6 52.9 Cr30Al1TiNb 250066 121 240 666 67 186 498 66 245 255 41.4 63.6 Cr30Al1TiNb 250065 132 285 685 61 213 521 58 264 265 41.8 64.0 Cr30Al1TiNbZr 250067 112 287 692 67 227 532 65 280 280 41.6 64.2 Cr30Al1TiNb 250068 174 261 666 69 205 498 65 297 336 44.9 83.2 e Cr28Al2 250129 269 334 674 66 - - - 191 224 31.8 56.8 e Cr28Al2Y 250130 167 322 693 63 252 522 53 220 244 32.6 57.9 e Cr28Al2YC1 250132 189 301 669 65 - - - 226 226 40.2 64.0 e Cr28Al2Nb.5C1 250133 351 399 725 57 334 522 33 285 353 40.8 78.9 e Cr28Al2Nb.5C1 250148 365 353 704 60 284 523 58 259 344 41.2 79.5 e Cr28Al2Nb1C1 250134 384 448 794 59 410 579 28 343 377 44.4 99.4 e Cr28Al2Nb1 C1 250147 350 372 731 57 306 547 49 309 384 43.0 89.1 e Cr28Al2Nb1C1Y 250149 298 415 784 53 339 528 27 340 400 45.1 99.2 e Cr28Al2TiC1 250137 142 379 745 59 327 542 29 311 314 44.0 70.4 e Cr28Al2TiC1 250138 224 348 705 61 278 510 46 247 296 42.2 66.5 Surname Chg Experiment No. m _gross in g / m ² m _net in g / m ² uum _spall in g / m ² T Alloy 602 CA 160483 412 8.66 7.83 0.82 T Alloy 602 CA 160483 425 5.48 5.65 -0.18 T Alloy 601 156125 403 51.47 38.73 12.74 T Alloy 690 111389 412 23.61 7.02 16.59 T Alloy 690 111389 421 30.44 -5.70 36.14 T Alloy 690 111389 425 28.41 -0.68 29,09 Cr30Al1La 2297 412 36.08 -7.25 43.33 Cr30Al1LaT 2300 412 41.38 -2.48 43.86 Cr30Al1TiLa 2298 412 49.02 -30.59 79.61 Cr30Al1TiNbLa 2306 412 40.43 16.23 24,20 Cr30Al1CLaTi 2308 412 42.93 -15.54 58.47 Cr30Al1CLa 2299 412 30.51 0.08 30.44 Cr30Al2La 2302 412 27.25 9.57 17.68 e Cr30Al1Ti 2301 412 8.43 6.74 1.69 Cr30Al1Ti 250060 421 43.30 -19.88 63.17 Cr30Al1TiNb 250063 421 32.81 -22.15 54.96 Cr30Al1TiNb 250066 421 26.93 -16.35 43.28 Cr30Al1TiNbZr 250065 421 25.85 -24.27 50.12 Cr30Al1TiNb 250067 421 41,59 -15.56 57.16 Cr28Al2 250068 421 42.69 -39.26 81,95 e Cr28Al2Y 250129 425 3.72 3.55 0.16 e Cr28Al2YC1 250130 425 4.68 4.90 -0.23 e Cr28Al2Nb.5C1 250132 425 3.94 5.01 -1.07 e Cr28Al2Nb.5C1 250133 425 2.56 3.98 -1.42 e Cr28Al2Nb1C1 250148 425 3.15 3.21 -0.07 e Cr28Al2Nb1C1 250134 425 3.34 4.23 -0.89 e Cr28Al2Nb1C1Y 250147 425 2.72 2.62 0.10 e Cr28Al2TiC1 250149 425 3.44 3.84 -0.40 e Cr28Al2TiC1 250137 425 3.62 4.24 -0.62 e Cr30Al1La 250138 425 3.87 4.28 -0.41

LIST OF REFERENCE NUMBERS

FIG. 1

Metal loss due to metal dusting as a function of aluminum and chromium content in a high carburizing gas with 37% CO, 9% H ₂ O, 7% CO ₂ , 46% H ₂ , the a _c = 163 and p (0 ₂ ) = 2 , 5 · 10 ^-27 has Hermse, CGM and van Wortel, JC: Metal dusting: relationship between alloy composition and degradation rate. Corrosion Engineering, Science and Technology 44 (2009), p. 182 - 185 ).

FIG. 2

Amounts of the phases in the thermodynamic equilibrium as a function of the temperature of Alloy 690 (N06690) using the example of the typical charge 111389.

FIG. 3

Amounts of the phases in the thermodynamic equilibrium as a function of the temperature of Alloy 693 (N06693) using the example of Alloy 3 from Table 2.

FIG. 4

Amounts of the phases in the thermodynamic equilibrium as a function of the temperature of Alloy 693 (N06693) using the example of Alloy 10 from Table 2.

Claims (18)

1. A nickel-chromium-aluminum alloy comprising (in % by mass) 24 to 33 % chromium, 1.8 to < 3.0 % aluminum, 0.10 to < 2.5 % iron, 0.001 to 0.50 % silicon, 0.005 to 2.0 % manganese, 0.00 to 0.60 % titanium, respectively 0.0002 to 0.05 % magnesium and/or calcium, 0.005 to 0.12 % carbon, 0.001 to 0.050 % nitrogen, 0.0001 to 0.20 oxygen, 0.001 to 0.030 % phosphorus, max. 0.010 % sulphur, max. 2.0 % molybdenum, max. 2.0 % tungsten, optionally 0.001 to < 0.50 % Nb, furthermore optionally containing a Y content of 0.01 to 0.20 %, a La content of 0.001 to 0.20 %, a cerium content of 0.001 to 0.20 %, a cerium composition metal content of 0.001 to 0.20 %, a zirconium content of 0.01 to 0.20 %, a B content of 0.0001 to 0.008 %, Co up 5.0 %, Cu up to max. 0.5 %, max. 0.5 % V, the remainder being nickel and the usual process-related impurities, wherein the following relations have to be met: $$\mathrm{Cr}+\mathrm{Al}\ge 28$$

   

   $$\mathrm{and\; Fp}\le 39.9\mathrm{with}$$

   

   $$\mathrm{Fp}=\mathrm{Cr}+\mathrm{0.272}*\mathrm{Fe}+\mathrm{2.36}*\mathrm{Al}+\mathrm{2.22}*\mathrm{Si}+\mathrm{2.48}*\mathrm{Ti}+\mathrm{0.374}*\mathrm{Mo}+\mathrm{0.538}*\mathrm{W}-\mathrm{11.8}*\mathrm{C}$$

   

   wherein Cr, Fe, Al, Si, Ti, Mo, W and C are the concentrations of the concerning elements in % by mass, wherein if Nb is used, the formula 4a will be complemented by a term with Nb: $$\mathrm{Fp}=\mathrm{Cr}+\mathrm{0.272}*\mathrm{Fe}+\mathrm{2.36}*\mathrm{Al}+\mathrm{2.22}*\mathrm{Si}+\mathrm{2.48}*\mathrm{Ti}+1.26*\mathrm{Nb}+\mathrm{0.374}*\mathrm{Mo}+\mathrm{0.538}*\mathrm{W}-\mathrm{11.8}*\mathrm{C}$$

   

   and Cr, Fe, Al, Si, Ti, Nb, Mo, W and C are the concentration of the concerning element in % by mass.
2. An alloy according to claim 1, comprising a chromium content of 25 to 33 %, in particular 26 to 33 %.
3. An alloy according to claim 1 or 2, comprising a chromium content of > 25 to < 30 %.
4. An alloy according to one of the claims 1 through 3, comprising an aluminum content of 2.0 to < 3.0 %.
5. An alloy according to one of the claims 1 through 4, comprising a silicon content of 0.001 to 0.20 %.
6. An alloy according to one of the claims 1 through 5, comprising a manganese content of 0.005 to 0.50 %.
7. An alloy according to one of the claims 1 through 6, comprising a titanium content of 0.001 to 0.60 %.
8. An alloy according to one of the claims 1 through 7, comprising a carbon content of 0.01 to 0.10 %.
9. An alloy according to one of the claims 1 through 8, in which zircon is completely or partially substituted by 0.001 to 0.2 % hafnium.
10. An alloy according to one of the claims 1 through 9, comprising maximum 0.5 % copper, wherein the formula 4a is complemented by a term with Cu: $$\mathrm{Fp}=\mathrm{Cr}+\mathrm{0.272}*\mathrm{Fe}+\mathrm{2.36}*\mathrm{Al}+\mathrm{2.22}*\mathrm{Si}+\mathrm{2.48}*\mathrm{Ti}+0.477*\mathrm{Cu}+\mathrm{0.374}*\mathrm{Mo}+\mathrm{0.538}*\mathrm{W}-\mathrm{11.8}*\mathrm{C}$$

    

    and Cr, Fe, Al, Si, Ti, Cu, Mo, W and C are the concentration of the concerning element in % by mass.
11. An alloy according to one of the claims 1 through 10, wherein impurities in concentrations of max. 0.002 % Pb, max. 0.002 % Zn, max. 0.002 % Sn are set.
12. An alloy according to one of the claims 1 through 11, in which the following formula is satisfied and thus a high-quality processing is achieved:

    Fa ≤ 60 (5a) < with Fa = Cr + 20.4*Ti + 201*C (6a) for an alloy without Nb, wherein Cr, Ti and C are the concentrations of the concerning elements in % by mass,

    respectively with Fa = Cr + 6.15*Nb + 20.4*Ti + 201*C (6b) for an alloy with Nb, wherein Cr, Nb, Ti and C are the concentrations of the concerning elements in % by mass.
13. An alloy according to one of the claims 1 through 12, in which the following formula is satisfied and thus a very good high-temperature strength/creep strength is achieved: $$\mathrm{Fk}\ge 45$$

    

    $$\mathrm{with\; Fk}=\mathrm{Cr}+\mathrm{19}*\mathrm{Ti}+\mathrm{10.2}*\mathrm{Al}+\mathrm{12.5}*\mathrm{Si}+\mathrm{98}*\mathrm{C}$$

    

    for an alloy without B and Nb, wherein Cr, Nb, Ti, Al, Si and C are the concentrations of the concerning elements in % by mass,
    respectively with Fk = Cr + 19*Ti + 34.3*Nb + 10.2*Al + 12.5*Si + 98*C + 2245*B (8b) for an alloy with B and Nb,
    wherein Cr, Ti, Nb, Al, Si, C and B are the concentrations of the concerning elements in % by mass.
14. A utilization of the alloy according to one of the claims 1 through 13 as band, sheet metal, wire, bar, longitudinally welded pipe and seamless pipe.
15. A utilization of the alloy according to one of the claims 1 through 13 for manufacturing seamless pipes.
16. A utilization of the alloy according to one of the claims 1 through 15 in heavily carburizing atmospheres.
17. A utilization of the alloy according to one of the claims 1 through 15 as structural part in the petrochemical industry.
18. A utilization of the alloy according to one of the claims 1 through 15 in furnace construction.

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