KR20080065749A - Zirconium alloys having excellent resistance property in both water and steam reaction - Google Patents

Abstract

A zirconium alloy composition is provided to improve resistance to cooling water and steam corrosion by including small amount of chromium, oxygen and silicon to niobium of an amount more than 1.5wt%. A zirconium alloy composition having excellent resistance to cooling water and steam corrosion, which comprises: niobium of 1.5 to 2.0wt%, chromium of 0.05 to 0.3wt%, oxygen of 800 to 1500ppm, silicon of 60 to 100ppm and zirconium of balance. The zirconium alloy composition may further comprise at least one of copper of 0.01 to 0.5wt% or iron of 0.05 to 0.3wt%.

Description

Zirconium alloys having excellent resistance property in both water and steam reaction}

1 is a graph showing the corrosion properties of zirconium alloys according to the addition amount of niobium,

2 is a graph showing the corrosion properties of the zirconium alloy according to the amount of copper added,

3 is a graph showing the corrosion properties of the zirconium alloy according to the iron addition amount.

The present invention relates to a zirconium alloy composition excellent in cooling water and water vapor corrosion resistance.

Zirconium alloys have a low neutron absorption cross-sectional area, excellent corrosion resistance and mechanical properties, and are materials for nuclear cladding, fuel assembly support grids, and structures within reactors for decades. Water Reactor has been widely applied in reactors. Of the zirconium alloys developed to date, Zircaloy-2, 1.20-1.70 wt% tin, 0.07-0.20 wt% iron, including tin (Sn), iron (Fe), chromium (Cr) and nickel (Ni) %, 0.05 to 1.15% chromium, 0.03 to 0.08% nickel, 900 to 1500 ppm oxygen, balance of zirconium) and zircaloy-4 (1.20 to 1.70% tin, 0.18 to 0.24% iron, chromium) 0.07 to 1.13 weight percent, 900 to 1500 ppm oxygen, nickel <0.007 weight percent, zirconium balance) alloys are most widely used.

Recently, however, as a part of improving the economic efficiency of nuclear reactors, high-burning operation, which uses more fuel replacement cycles, has been adopted to reduce the cycle cost of nuclear fuel.The fuel reacts with high-temperature, high-pressure cooling water and water vapor as much as the increased fuel replacement cycle. In this case, when the existing Zircaloy-2 and Zircaloy-4 are used as the fuel cladding material, the corrosion of the fuel is intensified.

Therefore, it is very urgent to develop a material that can be used as a high-combustion nuclear fuel cladding because it has excellent corrosion resistance to the high temperature, high pressure cooling water and steam, and thus, many studies have been conducted to develop a zirconium alloy with improved corrosion resistance. It is becoming. At this time, since the corrosion resistance of the zirconium alloy is greatly influenced by the type, amount of addition, processing conditions, heat treatment conditions, etc. of the zirconium alloy, it is most important to establish the optimum conditions having excellent corrosion resistance.

In US Patent No. 4,938,920, the amount of tin is reduced to 0 to 0.8% by weight, 0 to 0.3% by weight of vanadium and 0 to 1.0% by weight of niobium in order to develop an alloy with improved corrosion resistance than conventional Zircaloy-4. Was added, and 1000-1600 ppm of oxygen was added. At this time, the addition amount of iron is 0.2 ~ 0.8 wt%, the addition amount of chromium is 0 ~ 0.4 wt% and the total amount of iron, chromium and vanadium content is limited to 0.25 ~ 1.0 wt%.

U. S. Patent No. 5,254, 308 discloses an alloy containing niobium and iron in order to prevent degradation of the mechanical properties caused by lowering the tin content of the zirconium alloy to improve corrosion resistance. This alloy contains 0.45-0.75 weight percent tin and 0.4-0.53 weight percent iron, 0.2-0.3 weight percent chromium and 0.3-0.5 weight percent niobium, 0.012-0.3 weight percent nickel and 50-200 ppm silicon and It is composed of 1000 ~ 2000 ppm oxygen. The ratio of iron and chromium, which may affect the corrosion properties, was adjusted to 1.5, and the niobium content was determined according to the hydrogen absorption, and the fine corrosion of the nickel, silicon, carbon, and solute oxygen was finely controlled to improve the corrosion resistance and strength. To have it.

U.S. Patent No. 5,334,345 discloses 1.0 to 2.0 wt% tin, 0.07 to 0.7 wt% iron, 0.05 to 0.15 wt% chromium, 0.16 to 0.4 wt% nickel, 0.015 ~ to improve corrosion resistance and hydrogen absorption. An alloy composition is disclosed which consists of 0.3 wt% niobium, 20-500 ppm silicon and 900-1600 ppm oxygen.

U.S. Patent No. 5,366,690 mainly regulates the amounts of tin, nitrogen and niobium added, 0 to 1.5 wt% tin, 0 to 0.24 wt% iron, 0 to 0.15 wt% chromium, 0 to 2300 ppm nitrogen, An alloy composition containing 0-100 ppm silicon, 0-1600 ppm oxygen and 0-0.5 wt% niobium is disclosed.

U.S. Patent No. 5,211,774 discloses a zirconium alloy composition for improving mechanical properties and corrosive properties in a neutron irradiation environment. The composition of this alloy is 0.8-1.2 wt% tin, 0.2-0.5 wt% iron, 0.1-0.4 wt% chromium, 0-0.6 wt% niobium, 50-200 ppm silicon and 900-1800 ppm oxygen It is composed of, to change the content of silicon to reduce the change in hydrogen absorption and corrosion resistance.

As described above, the prior art of zirconium alloys mainly includes development of zircaloy-4 and various zirconium alloys, and zirconium alloys containing niobium, iron, and chromium have been developed to improve corrosion resistance. However, since nuclear power plants are constantly exposed to single-phase high temperature, high pressure cooling water, and abnormal steam atmosphere depending on the operating variables during the operation period, there is still a need to develop a zirconium alloy having higher corrosion resistance to cooling water and steam than the prior art. .

Accordingly, the present inventors have been studying to develop a high corrosion resistance zirconium alloy for cooling water and water vapor, the corrosion resistance of the zirconium alloy composition containing a small amount of chromium, oxygen and silicon in a high niobium content Compared with the conventional alloy Zircaloy-4 was confirmed that the present invention was completed.

An object of the present invention is to provide a zirconium alloy composition excellent in cooling water and water vapor corrosion resistance comprising a small amount of chromium, oxygen and silicon in a high niobium content of 1.5% by weight or more.

In order to achieve the above object, the present invention is a zirconium alloy composition excellent in corrosion resistance to water and water vapor including niobium 1.5 to 2.0% by weight, chromium 0.05 to 0.3% by weight, oxygen 800 to 1500 ppm, silicon 60 to 100 ppm and the balance of zirconium. To provide.

In addition, the present invention provides a zirconium alloy composition further comprising at least one of 0.01 to 0.5% by weight of copper or 0.05 to 0.3% by weight of iron in the zirconium alloy composition excellent in cooling water and water vapor corrosion resistance.

Furthermore, the present invention

Mixing and then dissolving the alloying elements to produce an ingot (step 1);

Heat-treating and cooling the ingot prepared in step 1 in the β region (step 2);

Hot rolling the ingot cooled in step 2 (step 3);

Preparing a zirconium alloy by cold rolling and heat-treating the hot rolled ingot in step 3 (step 4); And

It provides a method of producing a zirconium alloy composition comprising a final heat treatment (step 5) to relax the residual stress after the cold rolling of step 4.

In addition, the present invention provides a method for producing a zirconium alloy composition excellent in cooling water and water vapor corrosion resistance, step 1 provides a method for producing a zirconium alloy composition, characterized in that for producing an ingot by vacuum arc melting method.

Furthermore, the present invention is a method for producing a zirconium alloy composition excellent in cooling water and water vapor corrosion resistance, step 2 is a step of encapsulating the ingot of step 1 with a stainless steel sheet, and then heat-treated at 1000 ~ 1200 ℃ for 10 to 30 minutes After that, it provides a method of producing a zirconium alloy composition, characterized in that the step of quenching with water.

In addition, the present invention is a method of producing a zirconium alloy composition excellent in cooling water and water vapor corrosion resistance, step 3 is preheating the specimen treated in step 2 at a temperature of 550 ~ 750 ℃ hot rolling for 10 to 30 minutes It provides a method for producing a zirconium alloy composition, characterized in that the step of hot rolling at a reduction ratio of 60 to 80%.

Furthermore, the present invention is a method for producing a zirconium alloy composition excellent in cooling water and water vapor corrosion resistance, step 4 is annealing the hot-rolled specimen of step 3 for 20 to 40 minutes at 550 ~ 640 ℃, 40 to 60% Cold rolling is carried out at a reduction ratio of, and then the intermediate heat treatment for 1 to 3 hours at 560 ~ 600 ℃ provides a method for producing a zirconium alloy composition, characterized in that the step of performing repeated cold rolling.

In addition, the present invention provides a method for producing a zirconium alloy composition excellent in cooling water and water vapor corrosion resistance, the intermediate heat treatment and cold rolling of step 4 provides a method for producing a zirconium alloy composition, characterized in that repeated three to five times.

Furthermore, the present invention provides a method for producing a zirconium alloy composition excellent in cooling water and water vapor corrosion resistance, wherein the final heat treatment of step 5 is carried out at 440 ~ 580 ℃.

As used herein, "alloy composition" includes alloys as well as alloys made of such alloy compositions.

Hereinafter, the present invention will be described in detail.

Zirconium alloy composition excellent in cooling water and steam corrosion resistance according to the present invention is 1.5 to 2.0% by weight niobium; Chromium from 0.05 to 0.3 wt%; Oxygen 800-1500 ppm; Silicon 60-100 ppm; And the balance zirconium.

In addition, the zirconium alloy composition of the present invention may further comprise at least one of 0.01 to 0.5% by weight of copper or 0.05 to 0.3% by weight of iron.

Preferred compositions of the zirconium alloy compositions of the present invention are specifically as follows:

1) 1.5 to 2.0 wt% niobium, 0.05 to 0.3 wt% chromium, 800 to 1500 ppm oxygen, 60 to 100 ppm silicon and the balance zirconium;

2) 1.5-2.0 wt% niobium, 0.05-0.3 wt% chromium, 0.01-0.5 wt% copper, 800-1500 ppm oxygen, 60-100 ppm silicon and the balance zirconium;

3) 1.5 to 2.0% niobium, 0.05 to 0.3% chromium, 0.05 to 0.3% iron, 800 to 1500 ppm oxygen, 60 to 100 ppm silicon and the balance zirconium; or

4) Niobium 1.5-2.0 wt%, chromium 0.05-0.3 wt%, copper 0.01-0.5 wt%, iron 0.05-0.3 wt%, oxygen 800-1500 ppm, silicon 60-100 ppm and the balance zirconium.

In the zirconium alloy composition according to the present invention, the metal element used is composed of niobium, chromium, copper or iron and the balance zirconium. Since the addition of tin improves mechanical properties but lowers corrosion resistance, in the present invention, the content of tin is limited in the present invention, and niobium is added to the zirconium base so that the solid solution is not only enhanced to solid solution, but also formation of precipitates. We tried to improve the mechanical properties of zirconium by strengthening the precipitation. As the number of metal elements used in the composition increases, an unexpected zirconium precipitate phase may be formed in the zirconium base during neutron irradiation, thereby reducing the corrosion resistance of zirconium. Therefore, the metal elements are limited to four or less except zirconium.

Hereinafter, look at the role and effects of the elements added in the present invention.

(1) niobium ( Nb )

Niobium is known as the beta (β) phase stabilizing element of zirconium. The effects of niobium on corrosion have different consequences. It is generally known that when niobium is added at 0.5 wt% or less (low niobium content) or 1.0 wt% or more (high niobium content) its corrosiveness is improved.

The addition of niobium in the zirconium base beyond the high solubility improves the mechanical properties of the zirconium through the strengthening of the solid solution in the zirconium base as well as the precipitation strengthening due to the formation of precipitates.

1 is a graph showing the degree of corrosion resistance according to the content of niobium in a zirconium alloy, specifically, in a zirconium alloy in which 0.4 to 0.6 wt% tin and 0.1 to 0.2 wt% iron or chromium are added to zirconium. It is a graph showing the quantitative evaluation of the corrosion by measuring the weight increase of the specimen after corrosion for 400 days in a steam atmosphere of 400 ℃ while increasing the amount of niobium.

As shown in Fig . 1 , the higher the niobium content, the higher the corrosion resistance. In particular, even at a high niobium content of 1.5% by weight or more, the corrosion property of the zirconium alloy is improved. However, when the concentration of niobium is too high to form a large amount of precipitates, the corrosive nature of the niobium-added alloy may be sensitively changed depending on the heat treatment temperature. In the present invention, the niobium content is added at 1.5 to 2.0% by weight.

(2) chrome ( Cr )

Chromium is known to increase the corrosion resistance of zirconium alloys, the preferred content of chromium in the present invention is 0.05 to 0.3% by weight. If the content of chromium is less than 0.05% by weight, there is a problem that the corrosion resistance is lowered, and when the content of chromium is more than 0.3% by weight, workability is lowered.

(3) oxygen (O)

Oxygen dissolves in the zirconium base and causes solid solution strengthening, thereby enhancing the mechanical strength of the zirconium alloy. The oxygen content is preferably 800 to 1500 ppm, and if the oxygen content is less than 800 ppm, there is a problem that the mechanical properties are deteriorated. If the oxygen content is more than 1500 ppm, there is a problem that workability is deteriorated due to curing.

(4) silicon ( Si )

Silicon plays a role in reducing the hydrogen absorption at the zirconium base and retarding the transition of the corrosion with time. The content of the silicon is preferably 60 to 100 ppm, if the silicon content is less than 60 ppm has a problem of low corrosion resistance, if it exceeds 100 ppm there is a problem of low corrosion resistance.

(5) copper ( Cu )

Copper is known to increase the corrosion resistance of zirconium alloys and its corrosion resistance increases even with minor additions.

2 is a graph showing the degree of corrosion resistance according to the copper content in the zirconium alloy, specifically, 1.0 wt% niobium, 0.2-1.0 wt% tin, and 0.1-0.2 wt% iron or chromium in zirconium It is a graph showing the quantitative evaluation of the corrosion by measuring the weight increase of the specimen after corrosion for 400 days in a 400 ℃ steam atmosphere while increasing the amount of copper added to the added zirconium alloy.

As shown in Figure 2 , it can be seen that the addition of a small amount of 0.01% by weight or more greatly improve the corrosive properties of the zirconium alloy, the addition of 0.5% by weight or more can be seen that the effect of increasing the corrosion resistance is reduced. Therefore, in the present invention, the copper content is added in 0.01 to 0.5% by weight.

(6) iron ( Fe )

Iron increases the corrosion resistance of zirconium alloys and, in particular, changes the precipitate composition of zirconium alloys to increase their corrosion resistance.

3 is a graph showing the degree of corrosion resistance according to the iron content in the zirconium alloy, specifically, the addition amount of copper to the zirconium alloy containing 0.8 wt% or less of niobium and 0.2 to 1.0 wt% of tin is increased. After corrosion for 400 days in a 400 ℃ steam atmosphere while measuring the weight of the specimen by measuring the degree of corrosion quantitatively shows the graph.

As shown in Figure 3 , it can be seen that the addition of a small amount of 0.05% by weight or more greatly improve the corrosive properties of the zirconium alloy, the addition of 0.3% by weight or more can be seen that the effect of increasing the corrosion resistance is reduced. Therefore, in the present invention, the copper content is added at 0.05 to 0.3% by weight.

The zirconium alloy composition according to the present invention may be prepared using conventional methods well known in the art, and preferably

Mixing and melting the alloying elements to produce an ingot (step 1);

Heat-treating and cooling the ingot prepared in step 1 in the β region (step 2);

Hot rolling the ingot cooled in step 2 (step 3);

Preparing a zirconium alloy by cold rolling and heat-treating the hot rolled ingot in step 3 (step 4); And

Final heat treatment to relax residual stress after cold rolling of step 4 (step 5)

It can be produced by a method comprising a.

Hereinafter, the manufacturing method of the present invention will be described in detail step by step.

First, step 1 is a step of mixing the alloying elements such as iron, chromium, copper, oxygen, silicon, such as niobium in a predetermined ratio and then dissolve to prepare an ingot.

The ingot is preferably using a vacuum arc remelting (VAR) method, specifically low vacuum in the chamber, preferably 1 × 10 ^-5 to 0.5 torr, more preferably 0.1 to 0.3 torr At 800-1200 A, more preferably 900-1100 A by applying a current to dissolve, and then cooled to prepare an ingot in the form of a button or the like.

At this time, in order to prevent impurities from segregation or uneven distribution of the alloy composition in the button, dissolving is repeated several times, preferably 3 to 7 times, more preferably about 4 to 6 times. In the cooling process, it is preferable to cool by injecting an inert gas such as argon to prevent oxidation from occurring on the surface of the specimen.

Next, step 2 is a step of heat treatment and cooling the ingot prepared in step 1 in the β region.

The ingot is heat treated and cooled in the β region to homogenize the alloy composition in the ingot and to obtain fine precipitates. At this time, after the specimen is sealed with a stainless steel sheet in order to prevent oxidation of the specimen, preferably heat treatment at 1000 ~ 1200 ℃, more preferably 1020 ~ 1070 ℃, the heat treatment time is preferably 10 to 30 minutes 15-25 minutes are more preferable. It is preferable to quench with water of room temperature after heat processing.

Next, step 3 is a step of hot rolling the specimen treated in step 2. Specifically, the temperature of the hot rolling is preferably 550 ~ 750 ℃, more preferably 600 ~ 700 ℃ to preheat for 10 to 30 minutes, preferably 15 to 25 minutes, the reduction ratio is 60 to 80% Preferably, it is 65 to 75% and it is preferable to roll.

After removing the coating after hot rolling, it is preferable to remove the oxide film generated during β-heat treatment or hot rolling by using a pickling solution, and the oxide film remaining after pickling is removed by a mechanical method using an electric wire brush. can do.

Next, step 4 is a step of producing a zirconium alloy by cold rolling and heat treatment of the hot-rolled specimen in step 3.

The hot rolled specimen is preferably annealed at 550 to 640 ° C., more preferably at 570 to 620 ° C. for 20 to 40 minutes, preferably 25 to 35 minutes, and then a reduction ratio of 40 to 60%. Cold rolling is carried out to, followed by intermediate heat treatment for 1 to 3 hours at 560 ~ 600 ℃ and repeated cold rolling. At this time, the intermediate heat treatment and cold rolling may be repeated several times, preferably three to five times.

Step 5 is the final heat treatment after the cold rolling of step 4 to relax the residual stress.

The final heat treatment is preferably performed at 440 ~ 580 ℃, it is possible to produce a zirconium alloy composition according to the present invention by such a method.

Since the zirconium alloy composition according to the present invention comprising the above elements and contents is superior in corrosion resistance than the cooling water and steam corrosion resistance of Zircaloy-4, which is conventionally used as a result of the corrosion test (see Table 2), Combustion can also be usefully used for fuel cladding, support grids, structures, and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are only examples of the present invention, and the scope of the present invention is not limited to the following examples.

< Example  1> Manufacture of Zirconium Alloy

(One) Ingot ( Ingot ) Produce

Dissolution of niobium 1.5% by weight, 0.05% by weight of chromium, 1200 ppm of oxygen, 80 ppm of silicon and the balance of zirconium was carried out in the form of a button of 400 g using the vacuum arc dissolution (VAR) method. In order to prevent impurities from segregating or unevenly distributed alloy composition, five times of dissolution were performed. In order to prevent oxidation during dissolution, sufficient vacuum was formed to 0.2 torr, and then argon gas was injected into the chamber to apply an applied current of 1000. A, dissolution was carried out in a water-cooled copper crucible with a cooling water pressure of 1 kgf / cm ² and a diameter of 60 mm for about 3.5 minutes. After dissolution, the specimen was cooled to 0.2 torr in order to suppress oxidation of the surface of the specimen, and then cooled by injecting argon gas.

(2) β-heat treatment

β heat treatment was performed to homogenize the alloy composition in the ingot by solution treatment in the β region. In order to prevent oxidation of the specimen, the specimen was clad with a stainless steel plate having a thickness of 1 mm, held at 1050 ° C. for 20 minutes, dropped in a bath containing 100 L of water, and stirred with a rod to cool water.

(3) hot rolling

Hot rolling was performed using the rolling machine of a 100 ton scale. After preheating at 650 ° C. for 20 minutes, it was rolled at a pass rate of about 70% in one pass. After removing the coating after hot rolling, an oxide film generated during β-heat treatment or hot rolling was removed using a pickling solution having a volume ratio of hydrofluoric acid: nitric acid: water = 5: 45: 50. In addition, the oxide film remaining locally after pickling was completely removed mechanically using an electric wire brush.

(4) cold rolling and intermediate heat treatment

In order to remove the residual stress after hot rolling and to prevent the specimen from being damaged during the first cold working, it was annealed at 590 ° C for 30 minutes and then reduced to about 0.5 mm thickness in one pass using a 70 ton rolling mill. Primary cold rolling was performed at% reduction. After the first rolling, an intermediate recrystallization heat treatment was performed at 580 ° C. for 2 hours, and the second cold rolling was performed at a rolling reduction of 45%. After the second rolling, the intermediate recrystallization heat treatment was performed at 580 ° C. for 2 hours, and the third cold rolling was performed at a rolling reduction of 50%.

(5) final heat treatment

A zirconium alloy was prepared by performing a final heat treatment at 470 ° C. for 3 hours to relax the stress generated after cold rolling.

< Example  2>

The proportion of zirconium alloy composition is 1.5% by weight of niobium; 0.1 weight percent chromium; 1200 ppm oxygen; Silicon 80 ppm; And the balance zirconium was carried out in the same manner as in Example 1.

< Example  3>

The proportion of zirconium alloy composition is 1.5% by weight of niobium; 0.1 weight percent chromium; 0.1 weight percent iron; 1200 ppm oxygen; Silicon 80 ppm; And the balance zirconium was carried out in the same manner as in Example 1.

< Example  4>

The proportion of zirconium alloy composition is 1.8 wt% niobium; 0.2 wt% chromium; Iron 0.2% by weight; 1200 ppm oxygen; Silicon 80 ppm; And the balance zirconium was carried out in the same manner as in Example 1.

< Example  5>

The proportion of zirconium alloy composition is 2.0% by weight of niobium; 0.1 weight percent chromium; 0.1 weight percent iron; 1200 ppm oxygen; Silicon 80 ppm; And the balance zirconium was carried out in the same manner as in Example 1.

< Example  6>

The proportion of zirconium alloy composition is 1.5% by weight of niobium; 0.1 weight percent chromium; 0.05 weight percent copper; 1200 ppm oxygen; Silicon 80 ppm; And the balance zirconium was carried out in the same manner as in Example 1.

< Example  7>

The proportion of zirconium alloy composition is 1.8 wt% niobium; 0.2 wt% chromium; 0.1 wt% copper; 1200 ppm oxygen; Silicon 80 ppm; And the balance zirconium was carried out in the same manner as in Example 1.

< Example  8>

The proportion of zirconium alloy composition is 1.5% by weight of niobium; 0.05% by weight of chromium; 0.1 wt% copper; 0.1 weight percent iron; 1200 ppm oxygen; Silicon 80 ppm; And the balance zirconium was carried out in the same manner as in Example 1.

< Example  9>

The proportion of zirconium alloy composition is 1.8 wt% niobium; 0.1 weight percent chromium; 0.1 wt% copper; Iron 0.05% by weight; 1200 ppm oxygen; Silicon 80 ppm; And the balance zirconium was carried out in the same manner as in Example 1.

< Example  10>

The proportion of zirconium alloy composition is 2.0% by weight of niobium; 0.1 weight percent chromium; 0.05 weight percent copper; 0.1 weight percent iron; 1200 ppm oxygen; Silicon 80 ppm; And the balance zirconium was carried out in the same manner as in Example 1.

The zirconium alloy composition described above is shown in Table 1.

Composition ratio of zirconium alloy composition division Nb (% by weight) Cr (% by weight) Cu (% by weight) Fe (% by weight) O (ppm) Si (ppm) Zr Example 1 1.5 0.05 1200 80 Balance Example 2 1.5 0.1 1200 80 Balance Example 3 1.5 0.1 0.1 1200 80 Balance Example 4 1.8 0.2 0.2 1200 80 Balance Example 5 2.0 0.1 0.1 1200 80 Balance Example 6 1.5 0.1 0.05 1200 80 Balance Example 7 1.8 0.2 0.1 1200 80 Balance Example 8 1.5 0.05 0.1 0.1 1200 80 Balance Example 9 1.8 0.1 0.1 0.05 1200 80 Balance Example 10 2.0 0.1 0.05 0.1 1200 80 Balance

< Comparative example  1>

Zircaloy-4 used as a conventional commercial cladding tube was used.

< Experimental Example  1> corrosion test

In order to determine the corrosion resistance of the zirconium alloy composition according to the present invention, the following corrosion experiment was performed.

The zirconium alloys of Examples 1 to 10 and Comparative Example 1 were manufactured to have corrosion specimens having a size of 15 × 25 × 0.7 mm, and then mechanically polished to grid 1200. Dipping in a: 50 solution removes impurities on the surface and defects present on the surface. The surface area and initial weight were measured immediately before the surface-treated alloy was placed in an autoclave. Then, the specimen loaded in an autoclave having 360 ° C. water and 400 ° C. (10.3 MPa) steam atmosphere was corroded for 500 days and 400 days, and then the degree of corrosion was quantitatively evaluated by measuring the weight increase of the specimen. . The corrosion test results are shown in Table 2.

division Water at 360 ° C, 500 days (mg / dm ² ) Water vapor at 400 ° C, 400 days of corrosion (mg / dm ² ) Example 1 102 138 Example 2 99 131 Example 3 98 128 Example 4 113 124 Example 5 109 133 Example 6 117 149 Example 7 115 139 Example 8 119 158 Example 9 95 121 Example 10 122 143 Comparative Example 1 (Zircaloy-4) 135 180

As shown in Table 2, the zirconium alloys of Examples 1 to 10 of the zirconium alloy composition according to the present invention exhibited a corrosion degree of water of 99 to 102 mg / dm ^2, thereby indicating the zircaloy-4 of the comparative example (135 mg). / dm ² It can be seen that the lower than, even in the degree of corrosion of water vapor as 121 ~ 143 mg / dm ² , it can be seen that the corrosion degree is lower than Zircaloy-4 (180 mg / dm ² ). Therefore, the zirconium alloy composition according to the present invention has excellent corrosion resistance to water and corrosion resistance to water vapor, and therefore, high combustion of a nuclear power plant may be usefully used in nuclear fuel cladding, support grids, structures, and the like.

As described above, the zirconium alloy composition according to the present invention has excellent corrosion resistance in cooling water and steam compared to the conventional alloy Zircaloy-4, and thus the high-combustion fuel cladding tube, support grid, structure, etc. of a nuclear power plant. It can be usefully used.

Claims (9)

Zirconium alloy composition excellent in cooling water and water vapor corrosion resistance including niobium 1.5 to 2.0% by weight, chromium 0.05 to 0.3% by weight, oxygen 800 to 1500 ppm, silicon 60 to 100 ppm and the balance zirconium. The zirconium alloy composition of claim 1, wherein the zirconium alloy composition further comprises at least one of 0.01 to 0.5% by weight of copper or 0.05 to 0.3% by weight of iron. Mixing and melting the alloying elements to produce an ingot (step 1); Heat-treating and cooling the ingot prepared in step 1 in the β region (step 2); Hot rolling the ingot cooled in step 2 (step 3); Preparing a zirconium alloy by cold rolling and heat-treating the hot rolled ingot in step 3 (step 4); And Process for producing a zirconium alloy composition excellent in cooling water and water vapor corrosion resistance comprising the final heat treatment (step 5) to relax the residual stress after the cold rolling of step 4. The method of claim 3, wherein the step 1 is a step of preparing an ingot by a vacuum arc melting method. The method of claim 3, wherein the step 2 is the step of sealing the ingot of the step 1 with a stainless steel sheet, and then heat-treated for 10 to 30 minutes at 1000 ~ 1200 ℃, and then quenching with water and A method for producing a zirconium alloy composition excellent in water vapor corrosion resistance. The method of claim 3, wherein the step 3 is a step of preheating the specimen treated in the step 2 for 10 to 30 minutes at a temperature of hot rolling at 550 ~ 750 ℃, hot rolling at a reduction ratio of 60 to 80% Method for producing a zirconium alloy composition excellent in cooling water and water vapor corrosion resistance, characterized in that. The method of claim 3, wherein the step 4 is annealing the hot-rolled specimen of the step 3 for 20 to 40 minutes at 550 ~ 640 ℃, cold rolling at a reduction ratio of 40 to 60%, and then 560 ~ Method of producing a zirconium alloy composition excellent in cooling water and water vapor corrosion resistance characterized in that the step of performing the intermediate heat treatment for 1 to 3 hours at 600 ℃ repeatedly cold rolling. The method of claim 7, wherein the cold rolling and the intermediate heat treatment are repeated 3 to 5 times. The method of claim 3, wherein the final heat treatment of step 5 is performed at 440 to 580 ° C. 5.

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