Microalloyed high-toughness zirconium alloy and preparation method thereof

Abstract

The invention discloses a microalloyed high-toughness zirconium alloy and a preparation method thereof. The preparation method comprises the following steps: (1) alloy smelting; (2) alloy homogenization; (3) hot rolling treatment including primary hot rolling treatment and secondary hot rolling treatment; the temperature of the first hot rolling treatment is higher than that of the second hot rolling treatment. According to the invention, industrial pure zirconium is used as a matrix, trace elements such as boron, iron and oxygen are added, and a hot rolling process is adopted to prepare the microalloyed high-toughness zirconium alloy. Hot rolling can eliminate defects in cast ingots, densify and homogenize alloy structures, refine grains, improve microscopic structures and generate a large number of dislocations, the strength of the alloy is further improved through dislocation strengthening, crack propagation and cracking caused by local stress concentration can also be avoided through the uniform structures, and the quality of the cast ingots is improved. The excellent plasticity is maintained while the relatively high strength is maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy materials, and in particular to a microalloyed high-strength and toughness zirconium alloy and a preparation method thereof. Background Art

[0002] Zirconium-based materials are widely used in the medical field due to their high strength, good toughness, good corrosion resistance and good biocompatibility. At present, the tensile strength and yield strength of industrial pure zirconium are relatively low. For example, in some mechanical structural parts that need to withstand large static loads, such as high-strength bolts and large shaft parts, the strength of pure zirconium is difficult to meet the requirements and is prone to deformation or even fracture. Summary of the invention

[0003] In view of the above technical problems, the present invention provides a microalloyed high-strength and toughness zirconium alloy and a preparation method thereof. The microalloyed high-strength and toughness zirconium alloy provided by the present invention has high strength and low elastic modulus.

[0004] In order to achieve the purpose of the above invention, the present invention provides the following technical solutions:

[0005] In one aspect, the present invention provides a method for preparing a microalloyed high-strength and high-toughness zirconium alloy, comprising the following steps:

[0006] Step (1) alloy smelting;

[0007] Step (2) alloy homogenization;

[0008] Step (3) hot rolling treatment: the hot rolling treatment includes a first hot rolling treatment and a second hot rolling treatment; the temperature of the first hot rolling treatment is higher than that of the second hot rolling treatment.

[0009] As a preferred embodiment, the alloy homogenization temperature is 940-960° C.; the alloy homogenization time is 7-9 hours.

[0010] As a preferred embodiment, the temperature of the first hot rolling treatment is 890-910°C; the temperature of the second hot rolling treatment is 490-510°C;

[0011] Preferably, the first hot rolling process and the second hot rolling process are multi-pass rolling;

[0012] Preferably, the reduction rate of each of the multiple rolling passes is 5-10%.

[0013] As a preferred embodiment, the first hot rolling process further includes a water cooling operation;

[0014] Preferably, the second hot rolling treatment further includes ① water cooling operation, or ② annealing and furnace cooling;

[0015] Preferably, the annealing temperature is 490-510° C.; and the annealing time is 8-12 minutes.

[0016] As a preferred embodiment, step (3) further comprises a third hot rolling treatment; the temperature of the third hot rolling treatment is 290-310°C;

[0017] Preferably, the third hot rolling process is a multi-pass rolling process;

[0018] Preferably, the reduction rate of each of the multiple rolling passes is 5-10%.

[0019] As a preferred embodiment, the third hot rolling treatment further includes ① water cooling operation, or ② annealing and furnace cooling;

[0020] Preferably, the annealing temperature is 290-310° C.; and the annealing time is 8-12 minutes.

[0021] As a preferred embodiment, in step (3), the total deformation of the hot rolling treatment is 80-90%;

[0022] In some specific embodiments, the hot rolling process includes a first hot rolling process and a second hot rolling process, wherein the deformation amount of the first hot rolling process is 40-45%; the deformation amount of the second hot rolling process is 40-45%;

[0023] In some specific embodiments, the hot rolling treatment includes a first hot rolling treatment, a second hot rolling treatment and a third hot rolling treatment, the deformation amount of the first hot rolling treatment is 20-30%; the deformation amount of the second hot rolling treatment is 20-30%; the deformation amount of the third hot rolling treatment is 20-30%.

[0024] In some specific embodiments, in the first hot rolling process, the second hot rolling process and the third hot rolling process, each rolling process is preheated before rolling; the preheating temperature is the same as the hot rolling temperature; in the first hot rolling process, the second hot rolling process and the third hot rolling process, the preheating time before the first rolling process is 28 to 32 minutes, and the preheating time before the remaining rolling processes is 3 to 5 minutes. The present invention performs a heat preservation treatment before the first rolling process, which can prevent the alloy from cracking when rolling at a low temperature, and is also conducive to obtaining a precise hot rolling temperature.

[0025] As a preferred embodiment, the chemical composition of the microalloyed high-strength and toughness zirconium alloy, measured by mass fraction, includes:

[0026] Hafnium: 1.5% to 3%, Boron: 0.04% to 0.11%, Iron: 0.15% to 0.25%, Oxygen: 0.13% to 0.16%, and the balance is Zr and inevitable impurities.

[0027] In certain specific embodiments, in step (1), in order to ensure the uniformity of the alloy ingot obtained by alloy smelting, the alloy is smelted 5 to 6 times; after the alloy smelting, the operation of removing the oxide scale on the surface of the alloy ingot is also included, and specifically, 150 to 1500 mesh sandpaper can be used for grinding.

[0028] In certain specific embodiments, in step (2), the alloy homogenization is performed in an inert atmosphere.

[0029] In another aspect, the present invention provides a microalloyed high-strength and high-toughness zirconium alloy obtained by the above preparation method.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] The present invention uses industrial pure zirconium as a matrix, adds trace elements such as boron, iron and oxygen, and adopts a hot rolling process to prepare a microalloyed high-strength and tough zirconium alloy. Hot rolling can eliminate defects in the ingot, compact and homogenize the alloy structure, refine the grains, improve the microstructure, and generate a large number of dislocations. The strength of the alloy is further improved through dislocation strengthening, and the uniform structure will also avoid crack extension and cracking caused by local stress concentration, and maintain excellent plasticity while maintaining high strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the shape and size of the microalloyed high-strength and toughness zirconium alloy tensile specimen in an embodiment of the present invention.

[0033] Figure 2 : is the XRD diagram of the microalloyed high-strength and toughness zirconium alloy in the embodiment of the present invention.

[0034] Figure 3 This is a tensile data diagram of the microalloyed high-strength and toughness zirconium alloy in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The following embodiments are only some embodiments of the present invention, rather than all embodiments. Therefore, the detailed description in the embodiments of the present invention provided below is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the present invention. In the present invention, unless otherwise specified, all equipment and raw materials, etc. can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art.

[0036] Example 1

[0037] (1) Weigh industrial pure zirconium, iron oxide powder, boron oxide powder and iron boride powder according to mass percentage, and weigh the total weight of the alloy to 80 g;

[0038] (2) using a water-cooled copper crucible non-consumable vacuum arc furnace to melt in an argon atmosphere, repeatedly melting the ingot 5-6 times during melting; cooling the furnace to room temperature to obtain a Zr-B-Fe-O alloy ingot; and grinding and removing the oxide scale using 150-1500 mesh sandpaper;

[0039] (3) placing the alloy ingot in a vacuum tube furnace and heating it to 950° C. for homogenization for 8 h; during the homogenization process, argon gas is continuously introduced;

[0040] (4) heating the muffle furnace to 900°C at a heating rate of 10°C / min, placing the Zr-B-Fe-O alloy ingot in the muffle furnace and keeping it warm for 30 minutes; then immediately taking it out and rolling it on a twin-roll mill for multiple passes at 900°C, with the reduction of each rolling pass being 8% and the deformation of the alloy being about 44%; and water cooling it to room temperature;

[0041] (5) The water-cooled sample is placed in a 500° C. muffle furnace for 30 min, and then immediately taken out and rolled on a twin-roll mill for multiple passes at 500° C., with the reduction of each rolling pass being 6% and the total deformation of the 500° C. hot rolling being about 40%; the total deformation of the hot rolling deformation in step (4) and step (5) being 84%; water-cooled to room temperature; the surface oxide layer is polished and cleaned to obtain a Zr-B-Fe-O alloy.

[0042] The alloy sheet tested has a thickness of 2.5 mm and a composition of Zr-2.12Hf-0.25Fe-0.13O-0.04B. The phase composition and mechanical properties (tensile specimens such as Figure 1 As shown, the following examples are the same) and the results are as follows Figure 2 , Figure 3 shown.

[0043] Example 2

[0044] (1) Weigh industrial pure zirconium, iron oxide powder, boron oxide powder and iron boride powder according to mass percentage, and weigh the total weight of the alloy to 80 g;

[0045] (2) using a water-cooled copper crucible non-consumable vacuum arc furnace to melt in an argon atmosphere, repeatedly melting the ingot 5-6 times during melting; cooling the furnace to room temperature to obtain a Zr-B-Fe-O alloy ingot; and grinding and removing the oxide scale using 150-1500 mesh sandpaper;

[0046] (3) placing the alloy ingot in a vacuum tube furnace and heating it to 950° C. for homogenization for 8 h; during the homogenization process, argon gas is continuously introduced;

[0047] (4) heating the muffle furnace to 900°C at a heating rate of 10°C / min, placing the Zr-B-Fe-O alloy ingot in the muffle furnace and keeping it warm for 30 min; then immediately taking it out and rolling it on a twin-roll mill for multiple passes at 900°C, with the reduction of each rolling pass being 8% and the deformation of the alloy being about 40%; and water cooling it to room temperature;

[0048] (5) The water-cooled sample is placed in a 500° C. muffle furnace for 30 min, and then immediately taken out and rolled on a twin-roll mill for multiple passes at 500° C., with the reduction of each rolling pass being 6% and the total deformation of the 500° C. hot rolling being about 42%; the total deformation of the hot rolling deformation in step (4) and step (5) being about 82%; water-cooled to room temperature; the surface oxide layer is polished and cleaned to obtain a Zr-B-Fe-O alloy.

[0049] The thickness of the alloy plate tested was 2.5 mm, and the composition was: Zr-2.23Hf-0.15Fe-0.15O-0.08B. The phase composition and mechanical properties were as follows: Figure 2 , Figure 3 shown.

[0050] Example 3

[0051] (1) Weigh industrial pure zirconium, iron oxide powder, boron oxide powder and iron boride powder according to mass percentage, and weigh the total weight of the alloy to 80 g;

[0052] (2) using a water-cooled copper crucible non-consumable vacuum arc furnace to melt in an argon atmosphere, repeatedly melting the ingot 5-6 times during melting; cooling the furnace to room temperature to obtain a Zr-B-Fe-O alloy ingot; and grinding and removing the oxide scale using 150-1500 mesh sandpaper;

[0053] (3) placing the alloy ingot in a vacuum tube furnace and heating it to 950° C. for homogenization for 8 h; during the homogenization process, argon gas is continuously introduced;

[0054] (4) heating the muffle furnace to 900°C at a heating rate of 10°C / min, placing the Zr-B-Fe-O alloy ingot in the muffle furnace and keeping it warm for 30 min; then immediately taking it out and rolling it on a twin-roll mill for multiple passes at 900°C, with the reduction of each rolling pass being 8% and the deformation of the alloy being about 40%; and water cooling it to room temperature;

[0055] (5) The water-cooled sample is placed in a 500° C. muffle furnace for 30 min, and then immediately taken out and rolled on a twin-roll mill for multiple passes at 500° C., with the reduction of each rolling pass being 6% and the total deformation of the 500° C. hot rolling being about 42%; the total deformation of the hot rolling deformation in step (4) and step (5) being 82%; water-cooled to room temperature; the surface oxide layer is polished and cleaned to obtain a Zr-B-Fe-O alloy.

[0056] The thickness of the alloy plate tested was 2.5 mm, and the composition was: Zr-2.36Hf-0.20Fe-0.16O-0.11B. The phase composition and mechanical properties were as follows: Figure 2 , Figure 3 shown.

[0057] Example 4

[0058] (1) Weigh industrial pure zirconium, iron oxide powder, boron oxide powder and iron boride powder according to mass percentage, and weigh the total weight of the alloy to 80 g;

[0059] (2) using a water-cooled copper crucible non-consumable vacuum arc furnace to melt in an argon atmosphere, repeatedly melting the ingot 5-6 times during melting; cooling the furnace to room temperature to obtain a Zr-B-Fe-O alloy ingot; and grinding and removing the oxide scale using 150-1500 mesh sandpaper;

[0060] (3) placing the alloy ingot in a vacuum tube furnace and heating it to 950° C. for homogenization for 8 h; during the homogenization process, argon gas is continuously introduced;

[0061] (4) heating the muffle furnace to 900°C at a heating rate of 10°C / min, placing the Zr-B-Fe-O alloy ingot in the muffle furnace and keeping it warm for 30 min; then immediately taking it out and rolling it on a twin-roll mill for multiple passes at 900°C, with the reduction of each rolling pass being 8% and the deformation of the alloy being about 41%; and cooling it to room temperature with water;

[0062] (5) The water-cooled sample is placed in a 500°C muffle furnace for insulation for 30 minutes, and then immediately taken out and rolled on a twin-roll mill for multiple passes at 500°C, with the reduction of each rolling pass being 6% and the total deformation of the 500°C hot rolling being about 40%; the total deformation of the hot rolling deformation in step (4) and step (5) is 81%; then annealed in a 500°C muffle furnace for 10 minutes and then cooled in the furnace; the surface oxide layer is polished and cleaned to obtain a Zr-B-Fe-O alloy.

[0063] The thickness of the alloy plate tested was 2.5 mm, and the composition was: Zr-2.12Hf-0.25Fe-0.13O-0.04B. The phase composition and mechanical properties were as follows: Figure 2 , Figure 3 shown.

[0064] Example 5

[0065] (1) Weigh industrial pure zirconium, iron oxide powder, boron oxide powder and iron boride powder according to mass percentage, and weigh the total weight of the alloy to 80 g;

[0066] (2) using a water-cooled copper crucible non-consumable vacuum arc furnace to melt in an argon atmosphere, repeatedly melting the ingot 5-6 times during melting; cooling the furnace to room temperature to obtain a Zr-B-Fe-O alloy ingot; and grinding and removing the oxide scale using 150-1500 mesh sandpaper;

[0067] (3) placing the alloy ingot in a vacuum tube furnace and heating it to 950° C. for homogenization for 8 h; during the homogenization process, argon gas is continuously introduced;

[0068] (4) heating the muffle furnace to 900°C at a heating rate of 10°C / min, placing the Zr-B-Fe-O alloy ingot in the muffle furnace and keeping it warm for 30 min; then immediately taking it out and rolling it on a twin-roll mill for multiple passes at 900°C, with the reduction of each rolling pass being 8% and the deformation of the alloy being about 29%; and cooling it to room temperature with water;

[0069] (5) The water-cooled sample was placed in a muffle furnace at 500°C for 30 min, and then immediately taken out and rolled on a twin-roll mill for multiple passes at 500°C. The reduction in each pass was 6%, and the total deformation of the 500°C hot rolling was about 29%; water-cooled to room temperature;

[0070] (6) The water-cooled sample is placed in a 300°C muffle furnace for insulation for 30 minutes, and then immediately taken out and rolled on a twin-roll mill for multiple passes at 300°C, with the reduction of each rolling pass being 6%, and the total deformation of the 500°C hot rolling being about 24%; the total deformation of the hot rolling deformation in steps (4) and (5) is about 82%; then annealing is carried out in a 300°C muffle furnace for 10 minutes and then cooling is carried out with the furnace; then the surface oxide layer is polished clean and cleaned to obtain a Zr-B-Fe-O alloy.

[0071] The thickness of the alloy plate tested was 2.5 mm, and the composition was: Zr-2.12Hf-0.25Fe-0.13O-0.04B. The phase composition and mechanical properties were as follows: Figure 2 , Figure 3 shown.

[0072] from Figure 2-3 It can be seen that the zirconium alloy prepared by the present invention adds trace elements such as boron, which plays a role in refining grains and dispersing precipitation strengthening phases, thereby increasing the strength and toughness of the zirconium alloy. In addition, the zirconium alloy prepared by the present invention has good plasticity, low elastic modulus and higher strength.

[0073] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a microalloyed high-strength and tough zirconium alloy, characterized in that: The following steps are involved: Step (1) alloy smelting; Step (2) alloy homogenization; Step (3) hot rolling treatment: the hot rolling treatment includes a first hot rolling treatment and a second hot rolling treatment; the temperature of the first hot rolling treatment is higher than that of the second hot rolling treatment.

2. The preparation method according to claim 1, characterized in that: The alloy homogenization temperature is 940-960° C.; the alloy homogenization time is 7-9 hours.

3. The preparation method according to claim 1, characterized in that: The temperature of the first hot rolling process is 890-910°C; the temperature of the second hot rolling process is 490-510°C; Preferably, the first hot rolling process and the second hot rolling process are multi-pass rolling; Preferably, the reduction rate of each of the multiple rolling passes is 5-10%.

4. The preparation method according to claim 1, characterized in that: The first hot rolling process also includes a water cooling operation; Preferably, the second hot rolling treatment further includes ① water cooling operation, or ② annealing and furnace cooling; Preferably, the annealing temperature is 490-510° C.; and the annealing time is 8-12 minutes.

5. The preparation method according to claim 1, characterized in that: Step (3) further comprises a third hot rolling process; the temperature of the third hot rolling process is 290-310° C.; Preferably, the third hot rolling process is a multi-pass rolling process; Preferably, the reduction rate of each of the multiple rolling passes is 5-10%.

6. The preparation method according to claim 5, characterized in that: The third hot rolling treatment further includes ① water cooling operation, or ② annealing and furnace cooling; Preferably, the annealing temperature is 290-310° C.; and the annealing time is 8-12 minutes.

7. The preparation method according to claim 1, characterized in that: In step (3), the total deformation amount of the hot rolling treatment is 80 to 90%.

8. The preparation method according to claim 7, characterized in that: In the first hot rolling process, the second hot rolling process and the third hot rolling process, a preheating treatment is performed before each rolling process.

9. The preparation method according to claim 1, characterized in that: The chemical composition of the microalloyed high-strength and toughness zirconium alloy, measured by mass fraction, includes: Hafnium: 1.5% to 3%, Boron: 0.04% to 0.11%, Iron: 0.15% to 0.25%, Oxygen: 0.13% to 0.16%, and the balance is Zr and inevitable impurities.

10. The microalloyed high-strength and toughness zirconium alloy obtained by the preparation method according to any one of claims 1 to 9.

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