KR20090093483A - Zirconium alloy compositions having excellent corrosion resistance by the control of various metal-oxide and precipitate and preparation method thereof - Google Patents

Abstract

A zirconium alloying composition and a manufacturing method of the same are provided to have the excellent corrosion resistance by controlling the size of the deposition phase of the zircaloy. A zirconium alloying composition manufacturing method comprises followings. The mixture of the zirconium alloy composition element is dissolved and the ingot is manufactured. The manufactured ingot is forged in a beta domain. The forged ingot is cooled quickly after the solution treatment post-baking in the beta domain. The cooled ingot is heat-processed and extruded. The initial annealing is performed about the extruded intermediate product. The cold processing and middle heat treatment are repeated about the heat-treated intermediate product with the several occasions. The heat-treatment is performed at 560~650 °C for 15~40 minutes. The initial annealing is performed at 550~650 °C for 1~5 hours. The final heat-treatment is performed at 450~580°C for 2~10 hours.

Description

Zirconium alloy compositions having excellent corrosion resistance by the control of various metal-oxide and precipitate and preparation method

The present invention relates to a zirconium alloy composition excellent in corrosion resistance through the control of various oxygen compounds and precipitated phase and a method for producing the same.

The composition of the alloy is very important because the fuel cladding, support lattice, and reactor structures used in the nuclear fuel assembly are accompanied by deterioration of mechanical properties due to embrittlement and corrosive growth due to high temperature / high pressure corrosion environment and neutron irradiation. . Accordingly, the zirconium alloys having the low neutron absorption cross-sectional area and excellent mechanical strength and corrosion resistance have been widely used in pressurized water reactor (PWR) and boiling water reactor (BWR) reactors for decades. Zircaloy-2 (Zircaloy-2, 1.20-1.70 wt% tin, 0.07-0.20 wt% iron) containing tin (Sn), iron (Fe), chromium (Cr) and nickel (Ni) among conventionally developed zirconium alloys %, 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.

However, as part of improving the economic efficiency of nuclear reactors, high-combustion / long-cycle operation is used to increase the replacement cycle of nuclear fuel in order to reduce the cycle cost of nuclear fuel. When the reaction time is extended and the existing Zircaloy-2 and Zircaloy-4 are used as the fuel cladding material, there is a problem of intensifying the corrosion of the fuel.

Therefore, the development of a material that can be used as a high-combustion / long-cycle fuel assembly with excellent corrosion resistance against the high temperature and high pressure cooling water and water vapor is very urgent. Therefore, many studies to develop a zirconium alloy with improved corrosion resistance are needed. Are being performed. At this time, since the corrosion resistance of the zirconium alloy is greatly influenced by the kind addition amount of the element added, processing conditions, heat treatment conditions, etc., it is most important to establish the optimum conditions having excellent corrosion resistance.

Zirconium is similar in appearance to stainless steel and is used as the material of nuclear reactor because its thermal neutron absorption area is the smallest among metals. In general, zirconium is stable at room temperature and increases its reactivity at high temperatures. Alloy zircaloys having a small amount of tin, iron, chromium or the like added to zirconium have high corrosion resistance, and other alloys containing zirconium also have corrosion resistance. Chemically stable tetravalent oxide state, zirconium oxide (IV) is a material having a very high melting point of 2715 ℃, corrosion resistance, low thermal expansion coefficient.

Niobium (Nb) is a silvery white metal, but it looks blue due to its oxide film, and its specific gravity and hardness are similar to copper, but it is resistant to corrosion and easy to deform. It has a very high melting point of 2468 ℃, good heat resistance, thermal conductivity and stone resistance, and stable anodization film. Niobium is an insoluble metal element, and a form of niobium / iron alloy (FeNb) is used in the steelmaking industry. Niobium oxide is used to make final products for the niobium industry. These include nickel-niobium alloys, niobium-zirconium alloys, niobium-titanium alloys, pure niobium metals, lithium-niobate alloys, and the like used in high performance alloys.

Iron (Fe) is called steel or steel when it contains carbon or other elements. Among the elements, carbon has the greatest influence on the properties of iron. Carbon atoms are intercalated between iron atoms to inhibit the movement of iron atoms, so the more carbon, the higher the hardness, and the higher the hardness, the more easily iron is broken. do. Iron with this property is often alloyed with various elements. In iron alloy elements, chromium (Cr) forms a chromium film on the surface of iron to increase corrosion resistance, and nickel (Ni) forms a nickel film on the surface of iron to increase corrosion resistance, and vanadium (V) maintains hardness and tensile strength. And the ease of polishing, molybdenum (Mo) to reduce the friction force imposes the ease of polishing, tungsten (W) increases the wear resistance, manganese (Mn) increases the corrosion resistance and wear resistance, titanium (Ti) corrosion resistance Increase.

Chromium (Cr) is very stable at room temperature and does not interfere with air and water. In hydrochloric acid and dilute sulfuric acid, hydrogen is generated and dissolved to form a solution of chromium (II) salt, which is rapidly oxidized to chromium (III) by oxygen in the air. When chromium is immersed in oxidizing acids such as nitric acid, chromic acid, phosphoric acid, chloric acid, perchloric acid, and aqua regia, a solid thin film layer of oxide is formed on the metal surface, which becomes passive and does not dissolve. Due to the above properties, chromium and chromium alloys have corrosion resistance.

Since tin (Sn) does not change well in air, it is used for surface treatment of iron, steel, copper, and the like. The object of tin plating is widely used for tableware, art crafts, electronic parts, and the like, and also for use as an alloy such as soldering, bronze, gamma alloy, and fusible alloy.

In US Patent No. 5,940,464, iron weight is about 20-fold higher than that of US Patent No. 5,648,995, 0.02 to 0.4 wt% iron, 0.8 to 1.8 wt% niobium, 0.2 to 0.6 wt% tin, and 30 to 180 ppm carbon. An alloy composition and manufacturing process including 10 to 120 ppm of silicon, 600 to 1800 ppm of oxygen, and zirconium residues are disclosed, and to improve corrosion resistance and creep resistance.

U.S. Patent No. 5,211,774 discloses 0.2-0.5 wt% iron, 0.8-1.2 wt% tin, 0.1-0.4 wt% chromium, 0.0-0.6 wt% niobium, 50-200 ppm silicon, 900-1800 ppm oxygen and the balance of zirconium. An alloy composition and a manufacturing process are disclosed, and the amount of silicon in the zirconium alloy is changed to reduce the hydrogen absorption and the corrosiveness due to the process difference.

In US Patent No. 5,254,308, an alloy for maintaining mechanical properties according to a decrease in tin content, 0.4 to 0.53 wt% of iron, 0.45 to 0.75 wt% of tin, 0.2 to 0.3 wt% of chromium, and 0.3 to 0.5 wt% of niobium An alloy composition consisting of 0.012 to 0.030 wt% nickel, 50 to 200 ppm silicon, 1000 to 2000 ppm oxygen, and zirconium balance was disclosed. At this time, the iron / chromium ratio was 1.5, and the amount of niobium added was determined according to the amount of iron affecting the hydrogen absorption, and the amount of niobium, silicon, carbon, and oxygen was configured to have excellent corrosion resistance and mechanical strength.

EP 198,570 limits the niobium content to 1.0 to 2.5% by weight in binary alloys made of zirconium-niobium, suggesting that the corrosion resistance can be improved by presenting the heat treatment temperature introduced during the alloy manufacturing process.

As such, efforts are being made to improve the corrosion resistance and mechanical properties of zirconium alloys used as nuclear fuel assembly materials in nuclear power plants. In view of the trend of high combustion / long cycle operation, there is a continuing need for a zirconium alloy having excellent corrosion resistance to ensure the integrity of nuclear fuel in high combustion / long cycle operation.

Thus, the inventors of the present invention, while conducting research to improve the corrosion acceleration phenomenon which is the most problematic under high combustion / long cycle operation of nuclear fuel coating tube, support grid and structure made of zirconium alloy, 1.05 ~ 1.45% by weight; 0.1-0.7 wt% iron or 0.05-0.6 wt% chromium, or 0.1-0.7 wt% iron and 0.05-0.6 wt% chromium; And a zirconium alloy composition containing a balance of zirconium, by appropriately adjusting the type, amount and heat treatment temperature of the additive element, diversifying the type of oxygen compound formed during the oxidation process and controlling the size of the precipitated phase of the zirconium alloy for excellent corrosion resistance. It confirmed that it shows and completed this invention.

It is an object of the present invention to provide a zirconium alloy composition exhibiting excellent corrosion resistance through the control of various oxygen compounds and precipitation phases that can be used as materials for fuel coating tubes, support grids, structures, etc. used during high combustion / long cycle operation.

In addition, another object of the present invention to provide a method for producing the zirconium alloy composition.

In order to achieve the above object, the present invention is 1.05 ~ 1.45% by weight niobium exhibiting excellent corrosion resistance through the control of various oxygen compounds and precipitated phase; 0.1-0.7 wt% iron or 0.05-0.6 wt% chromium, or 0.1-0.7 wt% iron and 0.05-0.6 wt% chromium; And a zirconium balance and additionally 0.12% by weight of tin and a method for preparing the same.

The zirconium alloy composition according to the present invention has excellent corrosion resistance by appropriately adjusting the type, amount and heat treatment temperature of the additive element, diversifying the type of oxygen compound formed during the oxidation process and controlling the size of the precipitated phase of the zirconium alloy according to the present invention. Since it has a, it can be usefully used as nuclear fuel coating pipe, support grid, core structure material, etc. of light and heavy reactors.

1 is a schematic diagram showing the state of the stress in the oxide film at the metal and oxide film interface (L / S: low stress region, H / S: high stress region) according to the present invention.

The present invention provides the following zirconium alloy composition having excellent corrosion resistance through the control of various oxygen compounds and precipitation phases that can be used as materials for fuel coated pipes, support grids, structures, etc. used during high combustion / long cycle operation.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention is 1.05 ~ 1.45 wt% niobium; It provides a zirconium alloy composition containing any one of 0.1 to 0.7% by weight of iron or 0.05 to 0.6% by weight of chromium or 0.1 to 0.7% by weight of iron and 0.05 to 0.6% by weight of chromium and the balance of zirconium.

The zirconium alloy composition may additionally contain 0.12% by weight of tin.

The zirconium alloy composition according to the present invention is 1.15 to 1.25% by weight niobium; It is preferably composed of 0.12 to 0.45% by weight of iron or 0.05 to 0.45% by weight of chromium, or 0.12 to 0.45% by weight of iron and 0.05 to 0.45% by weight of chromium and the balance of zirconium.

The zirconium alloy composition may additionally contain 0.12% by weight of tin.

In order to obtain a zirconium alloy having excellent corrosion resistance, the zirconium alloy composition of the present invention improves the corrosion resistance by allowing the zirconium alloy composition of the present invention to be maintained in a wide layer in the oxide film for a long time. be (Fig. 1), the columnar shape of the oxide film is so formed by the compressive stress acting on the oxide film stability, it is necessary to form an oxygen-containing compounds that can continue to act in the compressive stress in the oxide film. As elements that can satisfy the above requirements, niobium (Nb), iron (Fe), and chromium (Cr) are evaluated as major alloying elements, and tin (Sn) is evaluated as secondary alloying elements.

The zirconium alloy composition according to the present invention includes various metal oxides produced during the oxidation process. The metal oxides are niobium oxide, iron oxide, chromium oxide, and the like, of which niobium oxide is NbO, Nb ₂ O ₃ , Nb ₃ O ₅ Etc., and the iron oxide is FeO, Fe ₃ O ₄ , Fe ₂ O ₃ Etc. are preferable, and the chromium oxide is preferably CrO, Cr ₂ O ₃ or the like, and the tin oxide is preferably SnO.

Each component element of the zirconium alloy composition according to the present invention will be described in detail below.

Niobium (Nb) serves to greatly improve the corrosion resistance of the zirconium alloy. However, if it is added at a high concentration (0.3%) or more, it is necessary to control the size and composition of the precipitate by introducing a specific heat treatment temperature and time to improve the corrosion resistance [Y.H. Jeong et al. J. Nucl Mater. vol 317 p. 1]. In view of the amount of niobium that is dissolved in the matrix and forms an appropriate amount of precipitated phase, the content of niobium preferably includes 1.05 to 1.45 wt%.

Iron (Fe) is an element added to improve the corrosion resistance of zirconium alloys and has been studied to improve the corrosion resistance when added to more than 0.3% by weight [A. Seibold er al .; Proceedings, International KTGENS Topical Meeting on Nuclear Fuel, TOPFUEL 95, Wurzburg, Germany, 12-15 March 1995, vol 2, p. 117]. Therefore, in the present invention, the iron content in the zirconium alloy composition was added in more than 0.1% by weight. However, when the iron content exceeds 0.7% by weight, there is a problem in workability, so the iron content of the zirconium alloy of the present invention is preferably 0.1 to 0.7% by weight.

Chromium (Cr), like iron, is a major element that increases the corrosion resistance of alloys. It is known that corrosion resistance is improved when added at least 0.2% [F. Garzarolli et al. ASTM-STP 1245 (1994) p. 709]. However, in the present invention, when the zirconium alloy is selected together with niobium and chromium, it is preferable that the minimum amount of chromium is 0.05% by weight as a high concentration of niobium is used.

Tin (Sn) is known as an α-phase stabilizing element in zirconium alloys, and serves to improve mechanical strength by solid solution strengthening. However, excessively increasing the amount decreases the corrosion resistance, and therefore, it is preferable to add it at 0.12% by weight, which does not significantly affect the reduction of the corrosion resistance.

In addition, the present invention provides a method for producing a zirconium alloy composition comprising the following steps 1 to 7.

Dissolving the mixture of the zirconium alloy composition elements to produce an ingot (step 1);

Forging the ingot prepared in step 1 in the β region (step 2);

Quenching the ingot forged in the step 2 after the solution heat treatment in the β region (step 3);

Thermally extruding the ingot cooled in step 3 (step 4);

Performing an initial heat treatment on the intermediate product extruded in step 4 (step 5);

Performing the cold working and intermediate heat treatment several times on the intermediate product heat-treated in step 5 (step 6); And

After cold working the intermediate product heat-treated in step 6, and performing a final heat treatment (step 7) comprising a variety of metal oxides and the excellent corrosion resistance by controlling the size of the precipitated phase comprising the step 1 to Provided is a method for producing the zirconium alloy composition of claim 14.

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

First, step 1 is a step of preparing an ingot made by melting the mixture of the zirconium alloy composition elements.

The ingot is preferably manufactured by a vacuum arc remelting (VAR) method, specifically, after maintaining a vacuum state in the chamber at 1 × 10 ^-5 torr, and argon (Ar) gas is 0.1 Ingot is injected into ˜0.3 torr, melted by applying a current of 500 to 1000 mA, and then cooled to prepare an ingot in the form of a button or the like.

At this time, it is preferable to dissolve repeatedly three to five times in order to prevent impurities from segregation or uneven distribution of the alloy composition in the ingot. In the cooling process, in order to prevent the occurrence of oxidation on the surface of the specimen, it is preferable to cool by injecting an inert gas such as argon.

Next, step 2 is a step of forging the ingot prepared in step 1 in the β-phase region.

In this step, it can be achieved by forging in the β-phase region of 1000 ℃ or more in order to break the cast structure in the prepared ingot, wherein the forging is preferably performed at 1000 ~ 1200 ℃. If the forging temperature is less than 1000 ℃, there is a problem that the ingot structure is not easily destroyed, if the temperature exceeds 1200 ℃ there is a problem that the heat treatment cost increases.

Next, step 3 is a step of quenching the ingot forged in the step 2 after the solution heat treatment in the β-phase region.

This step homogenizes the alloy composition in the ingot and cools and melts the ingot in the β region to obtain fine precipitates. In this case, after the specimen is sealed with a stainless steel sheet in order to prevent oxidation of the specimen, heat treatment is preferably performed at 1000 to 1200 for 50 to 70 minutes. After the heat treatment, the water is preferably cooled to 400 ° C. or lower in the β-phase region.

Next, step 4 is a step of hot working and extruding the ingot cooled in the step 3.

The ingot cooled in step 3 is hot working to produce an extruded shell suitable for cold working. The hot working of step 4 is preferably performed for 15 to 40 minutes at 560 ~ 650 ℃. If it is out of this temperature, it is difficult to obtain an intermediate product suitable for the next step of processing.

Next, step 5 is a step of performing an initial heat treatment for the intermediate product extruded in step 4.

The heat treatment is preferably performed for 1 to 5 hours at 550 ~ 650 ℃. If the initial heat treatment temperature is less than 580 ° C., there is a problem in workability, while if the initial heat treatment temperature is higher than 650 ° C., there is a problem that corrosion resistance is lowered due to the formation of coarse precipitated phase.

Next, step 6 is a step of manufacturing a zirconium alloy composition by repeatedly performing cold working and intermediate heat treatment for the intermediate product heat-treated in step 5 several times.

The cold working and the intermediate heat treatment of step 6 may be performed by cold working the intermediate product heat-treated in step 5 two to five times, and performing one to four intermediate heat treatments between the cold workings. At this time, the intermediate heat treatment is preferably performed for 3 to 5 hours at 550 ~ 650 ℃. If the heat treatment temperature is less than 550 ° C., there is a problem in workability. If the heat treatment temperature is higher than 650 ° C., there is a problem that corrosion resistance is lowered due to the formation of coarse precipitated phase. In addition, the cold working amount when performing the cold working is preferably 50 ~ 85%. Specifically, the primary cold working amount is more preferably 60 to 80%, the secondary cold working amount is 60 to 85%, and the third cold working amount is 65 to 85%. If the cold working amount is less than 50%, there is a problem that a product of a desired thickness cannot be obtained, and if it exceeds 85%, there is a problem in workability.

Next, step 7 is a step of performing a final heat treatment after cold working the intermediate product heat-treated in step 6 above.

 Cold working of the composition is carried out to increase creep resistance. At this time, the final heat treatment is preferably made in a vacuum, it is preferably carried out for 2 to 10 hours at 450 ~ 580 ℃. If the temperature is less than 450 ℃ there is a problem that the creep resistance is reduced, and if it exceeds 580 ℃ there is a problem that the mechanical strength is lowered. In addition, when the heat treatment time is less than 2 hours, there is a problem that the processed structure remains, and when more than 10 hours, the precipitated phase becomes coarse and corrosion resistance is deteriorated.

Hereinafter, the present invention will be described in detail by Examples and Experimental Examples. However, the following Examples and Experimental Examples are only illustrative of the present invention, and the content of the present invention is not limited by the following Examples and Experimental Examples.

< Example  1> Preparation of Zirconium Alloy Composition

(One) ingot  Produce

1.2 wt% niobium, 0.2 wt% iron and the balance of zirconium were prepared by vacuum arc melting (VAR) method. The zirconium used was a nuclear grade sponge zirconium as specified in ASTM B349, and the alloy element was a high purity product of 99.99% or more. In order to prevent impurities from segregating or unevenly distributed alloy composition, four times of dissolution were performed, and in order to prevent oxidation during dissolution, the vacuum was sufficiently maintained in the chamber to 1 × 10 ^-5 torr and then high purity (99.99%) The ingot was prepared in a water-cooled copper crucible having a cooling water pressure of 1 kgf / cm ² and a diameter of 60 mm by applying an applied current of 500 kPa while injecting (99.99%) argon gas.

(2) β-forging

Forging was performed in the β phase region at 1100 ° C. in order to break the cast structure in the prepared ingot.

(3) β- Hardening

The solution heat treatment was performed for 15 minutes in the β-phase region of 1050 ℃ to break the cast structure in the prepared ingot. After the heat treatment was completed, the ingot was quenched by dropping it into a water-filled water bath at room temperature to form martensite tissue or widmanstatten tissue.

(4) hot working

The β-sintered material was processed into a hollow billet and then hot extruded at 630 ° C. for 15 minutes to prepare an intermediate product suitable for cold working.

(5) initial heat treatment

The hot extruded material was subjected to initial heat treatment at 580 ° C. for 3 hours.

(6) cold working and intermediate heat treatment

The intermediate product, which was initially heat treated, was cold worked and subjected to an intermediate heat treatment at 580 ° C. for 3 hours.

(7) final heat treatment

The intermediate product after the intermediate heat treatment was cold worked, and the final heat treatment was performed at 510 ° C. for 3 hours in a vacuum state.

< Example  2-18>

A zirconium alloy composition having the excellent corrosion resistance was prepared in the same manner as in Example 1 except for the chemical composition constituting the zirconium alloy composition and the stepwise heat treatment conditions. The chemical composition and the stepwise heat treatment conditions constituting the zirconium alloy composition are shown in Table 1 below.

< Comparative example  1-6>

A zirconium alloy composition having the excellent corrosion resistance was prepared in the same manner as in Example 1 except for the chemical composition constituting the zirconium alloy composition and the stepwise heat treatment conditions. The chemical composition and the stepwise heat treatment conditions constituting the zirconium alloy composition are shown in Table 1 below.

division Chemical composition Step by step heat treatment conditions Niobium (wt%) Iron (% by weight) Chromium (% by weight) Tin (% by weight) Zirconium (wt%) Initial heat treatment (h: hour) Intermediate heat treatment (h: hour) Final heat treatment (h: hour) Example 1 1.2 0.2 - - Balance 580 ℃ x3h 580 ℃ x3h 510 ℃ x3h Example 2 1.2 0.2 - - Balance 600 ℃ x2h 600 ℃ x2h 510 ℃ x3h Example 3 1.2 0.35 - - Balance 580 ℃ x3h 580 ℃ x3h 510 ℃ x3h Example 4 1.2 0.35 - - Balance 600 ℃ x2h 600 ℃ x2h 510 ℃ x3h Example 5 1.2 0.6 - - Balance 580 ℃ x3h 580 ℃ x3h 510 ℃ x3h Example 6 1.2 0.6 - - Balance 600 ℃ x2h 600 ℃ x2h 510 ℃ x3h Example 7 1.2 0.6 - 0.12 Balance 580 ℃ x3h 580 ℃ x3h 510 ℃ x3h Example 8 1.2 0.6 - 0.12 Balance 600 ℃ x2h 600 ℃ x2h 510 ℃ x3h Example 9 1.2 - 0.1 - Balance 580 ℃ x3h 580 ℃ x3h 510 ℃ x3h Example 10 1.2 - 0.1 - Balance 600 ℃ x2h 600 ℃ x2h 510 ℃ x3h Example 11 1.2 - 0.3 - Balance 580 ℃ x3h 580 ℃ x3h 510 ℃ x3h Example 12 1.2 - 0.3 - Balance 600 ℃ x2h 600 ℃ x2h 510 ℃ x3h Example 13 1.2 - 0.3 0.12 Balance 580 ℃ x3h 580 ℃ x3h 510 ℃ x3h Example 14 1.2 - 0.3 0.12 Balance 600 ℃ x2h 600 ℃ x2h 510 ℃ x3h Example 15 1.2 - 0.5 - Balance 580 ℃ x3h 580 ℃ x3h 510 ℃ x3h Example 16 1.2 - 0.5 - Balance 600 ℃ x2h 600 ℃ x2h 510 ℃ x3h Example 17 1.2 0.35 0.3 - Balance 580 ℃ x3h 580 ℃ x3h 510 ℃ x3h Example 18 1.2 0.35 0.3 0.12 Balance 600 ℃ x2h 600 ℃ x2h 510 ℃ x3h Comparative Example 1 1.2 0.85 - - Balance 600 ℃ x2h 600 ℃ x2h 510 ℃ x3h Comparative Example 2 1.2 - 0.75 - Balance 600 ℃ x2h 600 ℃ x2h 510 ℃ x3h Comparative Example 3 0.8 - - - Balance 580 ℃ x3h 580 ℃ x3h 510 ℃ x3h Comparative Example 4 0.8 - - - Balance 600 ℃ x2h 600 ℃ x2h 510 ℃ x3h Comparative Example 5 0.5 - - 1.0 Balance 580 ℃ x3h 580 ℃ x3h 510 ℃ x3h Comparative Example 6 0.5 - - 1.0 Balance 600 ℃ x2h 600 ℃ x2h 510 ℃ x3h

< Experimental Example  1> Zirconium Alloy Composition  Manufacturability

The manufacturability of the zirconium alloy composition according to the present invention was carried out by observing the manufacturing process for Examples 1-18 and Comparative Examples 1-6.

Examples 1 to 18 and Comparative Examples 3 to 6 were prepared smoothly without damage during the heat treatment and processing process performed in the present invention, Comparative Examples 1 and 2 were severely damaged during the manufacturing process. By the above development, when 0.85% by weight of iron or 0.75% by weight of chromium is added to the alloy to which 1.2% by weight of niobium is added, it is difficult to secure excellent manufacturability. It can be seen that it is not desirable to excessively increase the total amount of iron or chromium.

< Experimental Example  2> corrosion test

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

The zirconium alloys of Examples 1 to 18 and Comparative Examples 3 to 6 were prepared into specimens having a length of 25 × 15 × 1 mm, and then immersed in a solution having a volume ratio of water: nitric acid: hydrofluoric acid (HF) of 50:40:10. Impurities on the surface and defects present on the surface are removed. The surface treated specimens were measured for surface area and initial weight just prior to loading into the autoclave. After corrosion for 90 days in 360 ℃ cooling water and 360 ℃ 70 ppm Li, by measuring the weight increase of the specimen, the degree of corrosion was quantitatively evaluated by calculating the weight increase relative to the surface area. The corrosion test results are shown in Table 2.

Examples 1 to 16 made of the zirconium alloy composition according to the present invention through Table 2 weight increase in the cooling water environment 27 ~ 32 mg / dm ² as compared to Comparative Examples 3 ~ 6 (33 ~ 35 mg / dm ² ) It can be seen that the amount of increase is small and the corrosion resistance is excellent. In addition, it can be seen that excellent in Examples 1 to 16 are low in Comparative Example 29 and by indicating the ^{42 mg / dm 2 3 ~ 6} (44 ~ 50 mg / dm 2) the weight increase in corrosion resistance than 70 ppm LiOH.

In addition, Examples 1, 3, 5, 7, 9, 11, 13, 15 and 17 and Examples 2, 4, 6, to determine the influence of the corrosion resistance according to the heat treatment temperature performed to control the size of the precipitate Comparing the corrosion performance of 8, 10, 12, 14, 16 and 18, the first and the intermediate heat treatment of the method of manufacturing the zirconium alloy composition of the present invention performed at 580 ℃ than in the case of 600 ℃ It can be seen that the weight gain decreases by 2 to 3 mg / dm ² due to the decrease in average size. Thus, it can be seen that the control of the intermediate heat treatment temperature of the method for producing a zirconium alloy composition of the present invention is very important. If the initial heat treatment and the intermediate heat treatment temperature are too low, the size of the precipitated phase is controlled to increase the corrosion resistance, but it is difficult to process. Suitable initial heat treatment and intermediate heat treatment temperature is 550 ~ 650 ℃ it can be seen that preferred.

division Weight increase (mg / dm ² ) 360 ℃ cooling water  360 ℃ 70 ppm Li Example 1 29.59 30.49 Example 2 32.28 33.33 Example 3 29.51 29.94 Example 4 31.94 31.18 Example 5 29.44 30.74 Example 6 31.04 31.47 Example 7 30.18 31.17 Example 8 32.42 32.62 Example 9 27.94 36.95 Example 10 31.43 41.54 Example 11 28.32 38.94 Example 12 31.51 42.33 Example 13 28.43 36.60 Example 14 31.54 42.26 Example 15 29.21 36.37 Example 16 30.72 39.57 Example 17 29.33 35.52 Example 18 30.24 38.72 Comparative Example 3 33.24 47.51 Comparative Example 4 34.12 50.22 Comparative Example 5 35.15 44.47 Comparative Example 6 35.22 44.53

Claims (18)

Niobium 1.05-1.45 wt%; 0.1-0.7 wt% iron or 0.05-0.6 wt% chromium, or 0.1-0.7 wt% iron and 0.05-0.6 wt% chromium; And a zirconium alloy composition having excellent corrosion resistance by diversification of types of metal oxides containing zirconium residues and size control of precipitated phases. The zirconium alloy composition according to claim 1, wherein the zirconium alloy composition has excellent corrosion resistance by varying the type of metal oxide further containing 0.12% by weight of tin and controlling the size of the precipitated phase. The zirconium alloy according to claim 1, wherein the zirconium alloy composition has excellent corrosion resistance by varying the type of metal oxide containing 1.15 to 1.25 wt% of niobium, 0.12 to 0.45 wt% of iron, and zirconium balance and controlling the size of the precipitated phase. Composition. 4. The zirconium alloy composition according to claim 3, wherein the zirconium alloy composition has excellent corrosion resistance by varying the type of metal oxide further containing 0.12% by weight of tin and controlling the size of the precipitated phase. The zirconium alloy according to claim 1, wherein the zirconium alloy composition has excellent corrosion resistance by varying the type of metal oxide containing 1.15 to 1.25 wt% of niobium, 0.05 to 0.45 wt% of chromium, and zirconium balance and controlling the size of the precipitated phase. Composition. The zirconium alloy composition according to claim 5, wherein the zirconium alloy composition has excellent corrosion resistance by varying the type of metal oxide further containing 0.12% by weight of tin and controlling the size of the precipitated phase. The zirconium alloy composition according to claim 1, wherein the zirconium alloy composition is used for varying the size of the type of metal oxide containing 1.05 to 1.45% by weight of niobium, 0.10 to 0.45% by weight of iron, 0.05 to 0.45% by weight of chromium and the balance of zirconium and controlling the size of the precipitated phase. Zirconium alloy composition having excellent corrosion resistance. The zirconium alloy composition according to claim 7, wherein the zirconium alloy composition has excellent corrosion resistance by varying the type of metal oxide further containing 0.12% by weight of tin and controlling the size of the precipitated phase. The method of claim 1, wherein the metal oxide of the zirconium alloy composition is selected from the group consisting of niobium oxide, iron oxide and chromium oxide having a variety of metal oxides and having excellent corrosion resistance by controlling the size of the precipitated phase. Zirconium alloy composition. 10. The zirconium alloy composition according to claim 9, wherein the metal oxide of the zirconium alloy composition further comprises tin oxide. 10. The method of claim 9, wherein the niobium oxide is selected from the group consisting of NbO, Nb ₂ O ₃ and Nb ₃ O ₅ Zirconium having excellent corrosion resistance by diversification of the type of metal oxide and controlling the size of the precipitated phase. Alloy composition. The method of claim 9, wherein the iron oxide is selected from the group consisting of FeO, Fe ₂ O ₃ and Fe ₂ O ₄ Zirconium having excellent corrosion resistance by varying the type of metal oxide and control the size of the precipitated phase. Alloy composition. 10. The zirconium alloy composition according to claim 9, wherein the chromium oxide is CrO, Cr ₂ O ₃ or a mixture thereof. The zirconium alloy composition according to claim 10, wherein the tin oxide is SnO, wherein the tin oxide is SnO. Dissolving the mixture of the zirconium alloy composition elements of claim 1 or 2 to produce an ingot (step 1); Forging the ingot prepared in step 1 in the β region (step 2); Quenching the ingot forged in the step 2 after the solution heat treatment in the β region (step 3); Thermally extruding the ingot cooled in step 3 (step 4); Performing an initial heat treatment on the intermediate product extruded in step 4 (step 5); Performing the cold working and intermediate heat treatment several times on the intermediate product heat-treated in step 5 (step 6); And After cold working the intermediate product heat-treated in the step 6, and performing a final heat treatment (step 7) comprising a variety of types of metal oxides and having excellent corrosion resistance by controlling the size of the precipitate phase The method for producing the zirconium alloy composition of claim 14. The method according to claim 15, wherein the hot working of step 4 is performed for 15 to 40 minutes at 560 to 650 ° C., and has excellent corrosion resistance by controlling the size of the precipitated phase and diversifying the type of metal oxide. The method for producing the zirconium alloy composition of claim 14. The method according to claim 15, wherein the heat treatment of step 5 is performed for 1 to 5 hours at 550 to 650 ° C. The method for producing the zirconium alloy composition of claim 14. 16. The method according to claim 15, wherein the final heat treatment of step 7 is performed for 2 to 10 hours at 450 to 580 ° C, and has excellent corrosion resistance by varying the type of metal oxide and controlling the size of the precipitated phase. The method for producing the zirconium alloy composition of claim 14.