RU2382685C1 - Manufacturing method of hardly-deformed multicomponent alloys - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: alloy for manufacturing of sheets contains basis and alloying components, including low-melt ingredients and components, forming dispersion strengthening phases. Hot rolling of ingots is implemented with surface kish in cases in conditions of restricted broadening. Cold rolling is implemented fractional with preliminary and intermediate hardening. Hot rolling and intermediate heating before hardening is implemented in the range of temperatures lower than fusion temperature of low-melt ingredient and higher than solution temperature of strengthening phases. Melting of ingot is implemented in induction furnaces. Ingot is subject to accelerated cooling. Between side faceplates of ingots and walls of case there are installed metallic inserts from material with yield limit in the range of rolling temperature.

EFFECT: prevention of crack formation in lamellar intermediate products of high-temperature solder alloys at its manufacturing, increasing of stability of mechanical properties and solder alloys homogeneity, ability of receiving of high-product mix with stable mechanical and chemical properties.

6 cl, 1 ex, 1 dwg

Description

The invention relates to the field of metal forming, in particular, to methods for manufacturing sheet semi-finished products from multicomponent alloys used as high-temperature solders for brazing metals in order to obtain high-strength and corrosion-resistant compounds.

The requirements for solders are quite stringent and contradictory, in particular, the solder must have a melting point that is high enough to provide strength to satisfy the requirements for metal parts that must be soldered to each other. The material must be compatible chemically and metallurgically with the base metal of the soldered parts. Solder is widely used in the form of sheets or foils with a thickness of 1.5 mm to 0.05 mm. Since the requirements for chemical composition and physical properties come first in the appointment of solder, the issue of manufacturability in the manufacture of semi-finished products from these alloys must be adapted to them.

Known alloy (solder), which contains 9.5-16.5 at.% Chromium, 0-5 at.% Iron, 10-15 at.% Silicon, 6-7 at.% Boron, 0-5 at.% molybdenum, the rest is nickel and random impurities (RF Patent No. 2167751, IPC V23K 35/30). The alloy has a melting point in the range from 960 ° C to 1200 ° C, preferably 1030 ° C-1130 ° C. The advantages of this alloy are their ability to solder at acceptable high temperatures and to form compounds that can be used at elevated temperatures under high voltage, corrosive media and fatigue factors without significant loss of mechanical properties.

In the manufacture of semi-finished products from a similar class of alloys, the following features should be taken into account:

- solders refer to complex alloyed, multicomponent systems, usually consisting of 4-6 elements;

- the content of alloying components in the alloy is usually quite high and the percentage of the main element may be less than 50%;

- compositions almost always have fusible components (eutectics and peritectics). The presence of a fusible component leads to zonal segregation of the original ingot (heterogeneity of the chemical composition over its cross section);

- almost all solders belong to the class of dispersion hardening alloys, i.e. when a solid solution is cooled to a certain temperature, two or more phases are formed with a highly developed interface between them - dispersion phases (second phases) and a dispersion medium (metastable solid matrix solution). The selection of the dispersion phase promotes the formation of cracks during rolling due to an additional change in volume and a decrease in the ductility of the metal.

A known method of producing rolled products from refractory and refractory metals and alloys, consisting of forging in cut rhombic dies with a single compression equal to 40-70%, a relative feed of 1.3-1.6 and subsequent rolling (AS No. 732041, MPK V21V 3 / 00). The method allows to obtain high-quality large-sized strips and sheets from various hardly deformable metals and alloys. This method is not used for processing alloys belonging to the class of dispersion hardening.

A known method of processing precipitation hardening nickel-based alloys, including preliminary deformation with a degree of not less than 80% at a temperature below the recrystallization temperature and final deformation under superplasticity, while the second stage of preliminary plastic deformation with degrees 25-95% in the temperature range from 1.0-1.2 the temperature of the onset of dissolution of the phase to the equicohesive is the temperature strength of the boundaries and grain bodies (RF Patent No. 2041284, IPC C22F 1/10). The method allows to obtain material with superplastic properties.

The method is not applicable for multi-composite alloys in which there is a significant amount of low-melting components.

A known method of manufacturing thin sheets of high-strength titanium alloys, including the preparation of card blanks, assembly of the package in a steel case, heating and hot rolling of the package, heat treatment, cutting the package and finishing operations of sheets (RF Patent No. 2243833, publ. 2005.01.10, IPC V21V 1 / 38). Rolling is carried out in conditions close to isothermal.

The disadvantage of this method is the formation of edge cracks during the rolling of high-temperature solders consisting of multicomponent alloys belonging to the class of dispersion hardening and including low-melting components (experimental data). The reason for this is the accumulation of large intermetallic compounds formed during casting and the presence of unrecrystallized grains blocked by dispersion decay. Especially these negative factors manifest themselves on the edges of the rolled sheet due to lateral tensile forces.

A known method for the production of low-carbon sheet steel, including steelmaking, hot and cold rolling of the sheet and annealing (RF Patent No. 2031962, IPC C21C 5/28, publ. 1995.03.27) is a prototype.

The method is not applicable for the manufacture of precipitation hardening alloys due to the formation of edge cracks during hot rolling.

The problem to which the claimed invention is directed, is to obtain semi-finished products of high-temperature solders, consisting of multicomponent alloys belonging to the class of dispersion hardening and including low-melting components.

The technical result of the invention is to prevent the formation of cracks in sheet semi-finished products of high-temperature solders during their manufacture, as well as increasing the stability of mechanical properties and homogeneity of the solder.

The technical result is achieved by the fact that in the method of manufacturing sheets from difficult to deform multicomponent alloys, including alloy smelting, casting ingots, hot and cold rolling of a sheet to a predetermined size, annealing, the alloy contains a base and alloying components, including low-melting components and elements forming dispersive hardening phases , hot rolling of ingots is performed with a surface oxide film in cases under constrained broadening conditions, and cold rolling is carried out fractionally from preliminary and intermediate refill hardening, while hot rolling and intermediate heating before hardening is carried out in the temperature range below the melting temperature of the low-melting component and above the dissolution temperature of the hardening phases.

To obtain a homogeneous melt, the ingot is smelted in induction furnaces.

To prevent the precipitation of the hardening phases, the ingot is subjected to accelerated cooling.

In order to reduce defects of liquation and shrinkage, the preferred height of the ingot should not exceed 20-100 mm and a width of 135-200 mm.

It is advisable to carry out hot rolling to a rolled thickness of 4-6 mm, because in this case, welding of the rolled sheets to each other is not observed.

To compensate for the lateral tensile forces arising in the edges between the lateral end surfaces of the ingots and the case walls, metal inserts of material are installed with a yield strength in the rolling temperature range of 0.8-0.9 of the yield strength of the rolled alloy.

Melting solder, with the aim of good mixing of the components, is preferably carried out in induction furnaces by known methods, providing good mixing of the melt. The ingots are predominantly subjected to rapid cooling, which suppresses the release of hardening phases, accompanied by large volume effects and, as a consequence, cracking of the ingots after casting. Finished ingots are machined. Then the surface of the ingots is subjected to artificial or natural oxidation to form a uniform oxide film. The oxide film prevents the ingots from being welded together during hot rolling. Ingots are set in a case. Hot rolling in a case creates conditions close to isothermal. The structure of the heating temperature for hot batch rolling is selected individually for each alloy and must meet the following two conditions:

- the temperature should be higher than the dissolution temperature of the hardening phases;

- the temperature should be below the melting temperature of the low-melting component of the melt.

Hot rolling of the sheets of solder is carried out in the conditions of constrained broadening, while the rolling stresses are aligned in width, formation of edge cracks is prevented and the quality of the edges is improved. For this, it is structurally and technologically expedient to install metal inserts from a material between the end surfaces of the ingots and the case plates with a yield strength in the range of rolling temperatures equal to 0.8-0.9 of the yield strength of the rolled alloy.

It is preferable to conduct hot rolling to a rolled thickness of 4-6 mm, this ensures that the sheets are not welded together. In the process of hot batch rolling, the tackle turns out to be homogeneous, with a pronounced mechanical texture, casting pores are brewed and alloy grains are crushed, ductility increases to the level required for cold rolling.

The solders are cold-rolled up to the thickness of the tack, as a rule, equal to 1.5-0.05 mm. Rolling is carried out depending on the alloy with different fineness and a different number of intermediate hardening, determined empirically. The duration of the intermediate heating before quenching should ensure the passage of static recrystallization processes at a temperature above the dissolution temperature of the hardening phases and below the melting temperature of the low-melting component. Subsequent hardening is necessary to prevent the reinforcing phases from reappearing.

The implementation of the proposed method provides the ability to obtain a sheet of solder with a thickness of less than 0.05 mm from difficult to deform multicomponent alloys.

To test this invention, the alloy ПЖК-35 was used.

The chemical composition of the alloy, the mass fraction of elements,%:

Manganese - 34.0-37.0;

Chrome - 17.0-20.0;

Boron - 0.1-0.2;

Cobalt - 8.0-10.0;

Nickel is the base.

Impurities:

Iron <1.5;

Silicon <0.8.

The alloy was melted in the IST-016 induction crucible furnace. The temperature of the ingot casting is 1360 ^{± 20} ° С. The obtained ingots were mechanically processed to a thickness of 24 mm, covered with a lime mortar, kept in air until dry to form a uniform release film, then stacked in a row in a steel case, consisting of plates with dimensions of H × B × L = 16 × 650 × 450 mm, made of steel grade St3. Four blanks were placed in the case in width, on both sides were laid liners with a thickness of 20 ± 2 mm of titanium alloy cut in width in place to provide lateral constraint on the blanks.

Case heating before rolling was carried out in electric furnaces according to the regime: setting temperature 980 ° C, holding time 2.5 hours

The rolling was carried out on a rolling mill with a diameter of work rolls of 750 mm with interruptions and intermediate heating of the cases at the set temperature in the furnace 980 ° C in order to restore the plasticity resource of the solder blanks during the rolling process according to the following scheme for changing the thickness of the package (case):

Hi = 56-45 mm, heating 15 min

Hi = 45-37 mm, heating 15 min

Hi = 37-31-29 mm, heating 15 min

Hi = 29-23-21 mm, heating 12 min

Hi = 21-16-14 mm, heating 10 min

Hi = 14-11.5 mm

After hot rolling, the cases were opened. The photo shows blanks after removing the upper steel plates from three packages. The thickness of the blanks was 5 mm. Cracks on the lateral edges of the workpieces, in contrast to their piece rolling to this thickness without a package, were absent.

Next, the workpieces were subjected to subsequent hardening: setting temperature 1040 ° C, holding for 90 minutes, cooling in water. Cold rolling was carried out to a sheet thickness of 0.08 mm with intermediate recrystallization annealing and hardening.

The alloy of the above composition does not exhaust the purpose of the described method, this technology can be used to obtain sheet semi-finished products of high-temperature solders, consisting of multicomponent alloys belonging to the class of dispersion hardening and including low-melting component components. The method allows to obtain a wide range of products with stable mechanical and chemical properties.

Claims (6)

1. A method of manufacturing sheets of hardly deformable multicomponent alloys, including alloy smelting, casting ingots, hot and cold rolling of ingots to specified sheet sizes and annealing, characterized in that the alloy is melted containing a base and alloying components, including low-melting components and elements forming dispersion hardening phases, hot rolling of ingots is performed with a surface oxide film in cases under constrained broadening conditions, and cold rolling is carried out fractionally with preliminary and industrial weft quenching, the hot rolling and intermediate heating before quenching is carried out in the temperature range below the melting temperature fusible component and a higher dissolution temperature hardening phases. 2. The method according to claim 1, characterized in that the alloy is smelted in induction furnaces. 3. The method according to claim 1, characterized in that the ingot is subjected to accelerated cooling. 4. The method according to claim 1, characterized in that the preferred height of the ingot is 20-100 mm, and the width is 135-200 mm 5. The method according to claim 1, characterized in that the hot rolling is carried out to a rolled thickness of 4-6 mm 6. The method according to claim 1, characterized in that between the side end surfaces of the ingots and the walls of the case are metal inserts of material with a yield strength in the rolling temperature range of 0.8-0.9 of the yield strength of the rolled ingot.

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