Zirconium materials, their preparation methods, and applications

Abstract

This invention relates to the field of zirconium material processing, and discloses a zirconium material, its preparation method, and its application. The zirconium material preparation method includes: performing a roughing and rolling process I on a zirconium-containing forged slab to obtain a billet; and subjecting the billet to heat treatment I, rolling process II, and heat treatment II; the temperature of heat treatment I is (T). β -40)~(T β +50)℃; the temperature of the rolling treatment II is (T β -430)~(T β -330)℃; the temperature of the heat treatment II is (T β -380)~(T β -280℃; the zirconium-containing forged slab is a slab of R60702 zirconium alloy and / or R60700 zirconium alloy. This method achieves precise control of the microstructure of zirconium materials, effectively improves the reliability of zirconium structural components, and solves the problem that conventional processes cannot significantly improve the mechanical properties of zirconium materials.

Description

Technical Field

[0001] This invention relates to the field of zirconium material processing, specifically to a zirconium material, its preparation method, and its application. Background Technology

[0002] Zirconium metal, due to its low thermal neutron absorption cross section, good radiation stability, excellent strength-to-ductility ratio, and superior corrosion resistance, has become a key structural material in the nuclear and chemical industries. In recent years, low-alloy zirconium alloys have demonstrated wide-ranging cross-domain applications as key equipment component materials in the petrochemical, nuclear, and aerospace industries, particularly in heat exchangers, container linings, valves, cladding materials, spacecraft structural components, and conduits. With the continuous iteration of equipment technology, the requirements for the mechanical properties of zirconium alloys are constantly increasing, necessitating the development of effective strategies to broaden their application boundaries. To ensure the safety and reliability of equipment during service and extend its service life, extremely stringent requirements are placed on the mechanical properties of zirconium alloys, posing technical challenges to the microstructure control and heat treatment process optimization of zirconium alloys.

[0003] The four main approaches to metal strengthening include improving strength by altering the metal's microstructure or introducing defects. Solid solution strengthening and precipitation strengthening often require the addition of extra alloying elements; however, in industrial applications, it's difficult to adjust the alloying elements for established alloy grades. Dislocation strengthening requires significant cold plastic deformation of the sheet metal. During cold plastic deformation, the increased dislocation density leads to entanglement, thereby increasing strength and hardness; however, this strengthening method results in decreased plasticity. Among these strengthening approaches, grain refinement often brings a synergistic improvement in both strength and plasticity to some extent. Currently, the conventional production method for low-alloy zirconium alloy sheets is rolling followed by recrystallization annealing, resulting in an equiaxed microstructure. These zirconium alloys have relatively low mechanical properties, limiting their service life. Therefore, new methods are needed to control the microstructure of zirconium alloy sheets to improve their mechanical properties and further extend their service life. Summary of the Invention

[0004] The purpose of this invention is to overcome the bottlenecks of existing technologies and provide a method for preparing zirconium materials. This method achieves effective control of the microstructure of zirconium materials, further improves the reliability of zirconium material structural components, and solves the problem that conventional processes cannot significantly improve the mechanical properties of zirconium materials, thereby enabling them to be better applied in fields such as petrochemicals, nuclear industry, and aerospace.

[0005] To achieve the above objectives, as mentioned above, the first aspect of the present invention provides a method for preparing zirconium material, the method comprising: performing a rolling process I on a zirconium-containing forged slab to obtain a billet, and performing heat treatment I, rolling process II, and heat treatment II on the billet; The temperature of heat treatment I is (T) β -40)~(T β +50)℃; The temperature of the rolling process II is (T) β -430)~(T β -330)℃; The temperature of the heat treatment II is (T) β -380)~(T β -280)℃; The zirconium-containing forged slab is a slab of R60702 zirconium alloy and / or a slab of R60700 zirconium alloy.

[0006] Preferably, the thickness of the zirconium-containing forged slab is 160-220 mm.

[0007] Preferably, the conditions for the initial rolling process I include: a temperature of (T) β -150)~(T β -130)℃, rolling reduction rate 40-60%.

[0008] Preferably, the heat treatment time I is 80-120 min.

[0009] Preferably, the preparation method further includes: quenching the billet before the rolling process II.

[0010] Preferably, the rolling reduction rate of the rolling process II is 60-75%.

[0011] Preferably, the preparation method further includes: cooling the billet after rolling process II.

[0012] The second aspect of the present invention provides a zirconium material prepared by a method thereof, wherein the microstructure of the zirconium material is an equiaxed crystal structure of 4.75-6.84 μm.

[0013] Preferably, the zirconium material has a tensile strength of 394-500 MPa, a yield strength of 288-370 MPa, and an elongation of 26-40%.

[0014] A third aspect of this invention provides the application of zirconium materials in equipment used in the petrochemical, nuclear, and aerospace industries.

[0015] Through the above technical solution, the present invention provides a method for preparing zirconium material. This method involves performing a roughing and rolling process I on a zirconium-containing forged slab, combined with heat treatment I, rolling process II, and heat treatment II techniques, and limiting the temperature of heat treatment I to (T...). β -40)~(T β+50)℃, the rolling treatment II temperature is (T β -430)~(T β -330)℃, the temperature limit for heat treatment II is (T β -380)~(T β The microstructure of zirconium material can be precisely controlled at -280℃, resulting in a uniform and fine microstructure without obvious coarse grains, which significantly improves the mechanical properties of the zirconium. The fine equiaxed phases not only regulate plastic deformation but also ensure high plastic deformation capacity; the abundant grain boundaries effectively hinder dislocation slip, enhancing the strength of the system. Furthermore, this preparation method avoids the cumbersome and time-consuming multi-stage rolling processes of traditional methods, making the entire process simple and easy to control. Attached Figure Description

[0016] Figure 1 This is a metallographic image of the zirconium alloy slab in step (4) of Embodiment 1 of the present invention; Figure 2 This is a metallographic image of the zirconium alloy slab in step (4) of embodiment 3 of the present invention; Figure 3 This is a metallographic image of the zirconium material finally obtained in Embodiment 1 of the present invention; Figure 4 This is a metallographic image of the zirconium material finally obtained in Embodiment 3 of the present invention; Figure 5 This is a metallographic image of the zirconium material finally obtained in Comparative Example 4 of this invention. Detailed Implementation

[0017] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0018] As mentioned above, the first aspect of the present invention provides a method for preparing zirconium material, the method comprising: performing a rolling process I on a zirconium-containing forged slab to obtain a billet, and performing heat treatment I, rolling process II, and heat treatment II on the billet; The temperature of heat treatment I is (T) β -40)~(T β +50)℃; The temperature of the rolling process II is (T) β -430)~(T β -330)℃; The temperature of the heat treatment II is (T)β -380)~(T β -280)℃; The zirconium-containing forged slab is selected from slabs of R60702 zirconium alloy and / or R60700 zirconium alloy.

[0019] The inventors discovered in their research that by performing a roughing rolling process I on a zirconium-containing forged slab, combined with heat treatment I, rolling process II, and heat treatment II techniques, and by limiting the temperature of heat treatment I to (T... β -40)~(T β +50)℃, the rolling treatment II temperature is (T β -430)~(T β -330)℃, the temperature limit for heat treatment II is (T β -380)~(T β The microstructure of zirconium can be controlled at -280℃, resulting in a uniform and fine microstructure without obvious coarse grains, significantly improving its mechanical properties. The fine equiaxed phases not only regulate plastic deformation but also ensure high plastic deformation capacity; the abundant grain boundaries effectively hinder dislocation slip, enhancing the system's strength. Furthermore, this preparation method avoids the cumbersome and time-consuming multi-stage rolling processes of traditional methods, making the entire process simple and easy to control.

[0020] In this invention, the zirconium-containing forged slab can be a slab of R60702 zirconium alloy or a slab of R60700 zirconium alloy.

[0021] In this invention, T β The temperature at which the material undergoes a phase transition is denoted as .

[0022] In order to further control the grain characteristics in the microstructure to improve the mechanical properties of zirconium materials, preferably, the thickness of the zirconium-containing forged slab is 160-220 mm, which can be 160 mm, 180 mm, 200 mm, 220 mm, or any value within any two of these ranges.

[0023] In this invention, the conditions for the initial rolling process I include: a temperature of (T) β -150)~(T β -130)℃, can be used for T β -150℃, T β -140℃, T β-130℃, or any value within the range formed by any two of these values; the rolling reduction rate is 40-60%, which can be 40%, 50%, 60%, or any value within the range formed by any two of these values. By controlling the conditions of the above-mentioned billet rolling treatment I within this specific range, it is possible to further regulate the grain characteristics in the microstructure to improve the mechanical properties of zirconium materials.

[0024] In order to further control the grain characteristics in the microstructure to improve the mechanical properties of zirconium, preferably, the heat treatment time I is 80-120 min, which can be 80 min, 100 min, 120 min, or any value within any two of these ranges.

[0025] To further control grain characteristics at the microstructure level to improve the mechanical properties of zirconium, the preparation method preferably further includes quenching the billet before the rolling process II. More preferably, considering the ability to further control grain characteristics at the microstructure level to improve the mechanical properties of zirconium, the quenching process uses water as the medium.

[0026] Considering the ability to further regulate grain characteristics in the microstructure to improve the mechanical properties of zirconium materials, the quenching treatment temperature is ≤40℃ and the time is ≤20s.

[0027] From the perspective of being able to further control grain characteristics in the microstructure field to improve the mechanical properties of zirconium materials, preferably, the conditions of the rolling treatment II also include: the rolling reduction rate is 60-75%, which can be 60%, 65%, 70%, 75%, or any value within any two of these values.

[0028] To further control grain characteristics at the microstructure level to improve the mechanical properties of zirconium, a cooling treatment is preferably performed before heat treatment II. The cooling treatment can employ conventional cooling methods selected in the art, such as air cooling. Exemplarily, the billet obtained after rolling treatment II is placed in air for natural cooling.

[0029] In this invention, preferably, the heat treatment II time is 50-70 minutes, which can be 50 minutes, 60 minutes, 70 minutes, or any value within any two of these ranges. By controlling the heat treatment II time within the aforementioned specific range, grain characteristics can be further modulated in the microstructure to improve the mechanical properties of the zirconium material.

[0030] The second aspect of the present invention provides a zirconium material prepared by the preparation method described in the first aspect above, wherein the microstructure of the zirconium material is an equiaxed crystal structure of 4.75-6.84 μm.

[0031] In this invention, the tensile strength of the zirconium material is 394-500 MPa, which can be 394 MPa, 450 MPa, 475 MPa, 500 MPa, or any value within any two of these ranges; the yield strength is 288-370 MPa, which can be 288 MPa, 300 MPa, 320 MPa, 340 MPa, 370 MPa, or any value within any two of these ranges. The elongation is 26-40%, which can be 26%, 30%, 35%, 40%, or any value within any two of these ranges. More preferably, the tensile strength of the zirconium material is 450-500 MPa, the yield strength is 315-370 MPa, and the elongation is 30-32%.

[0032] The third aspect of this invention provides the application of the zirconium material described in the second aspect above in the fields of petrochemicals, nuclear industry and aerospace.

[0033] In this invention, the petrochemical, nuclear industry and aerospace fields have high requirements for key equipment. By applying the above-mentioned zirconium material to equipment in the petrochemical, nuclear industry and aerospace fields, it has excellent mechanical properties and is widely used, such as heat exchangers, container linings, valves, cladding materials, spacecraft structural components such as agitators and conduits.

[0034] A relatively preferred embodiment of the present invention provides a method for preparing zirconium material, comprising the following steps: (1) A zirconium-containing forged slab with a thickness of 160-220 mm is subjected to a temperature of (T) β -150)~(T β The billet is obtained by rolling at -130℃ with a reduction rate of 40-60%. (2) After the billet in step (1) has cooled to room temperature, then at a temperature of (T) β -40)~(T β Heat treatment I was carried out at +50℃ for 80-120 minutes. (3) The billet after heat treatment I is subjected to quenching treatment, with water temperature ≤ 40℃ and immersion time ≤ 20s, until it is cooled to room temperature; (4) The temperature of the quenched billet is (T) β -430)~(T β -330), rolling treatment is carried out under the condition of rolling reduction rate of 60-75%; (5) The billet subjected to the above rolling process II is cooled and then subjected to a temperature of (T) β -380)~(T βHeat treatment II was performed at -280℃ for 50-70 minutes, followed by air cooling to room temperature after heat treatment to obtain ultrafine crystalline zirconium material.

[0035] The zirconium material prepared by the above-described particularly preferred embodiments can improve the mechanical properties of zirconium by controlling the grain characteristics in the microstructure.

[0036] The present invention will be described in detail below through embodiments. In the following embodiments, both the R60702 and R60700 zirconium alloy slabs are self-produced.

[0037] T corresponding to the R60702 type zirconium alloy slab β The temperature is 910~930℃; T corresponding to R60700 type zirconium alloy slab β The temperature is 900~920℃; In the following examples, the room temperature is 15-30°C.

[0038] Example 1 (1) A zirconium alloy slab (model: R60702) with a thickness of 200 mm is placed on a hot rolling mill for roughing rolling. The rolling temperature is T = (T β At -130)℃, a rolling reduction of 50% was used to obtain a zirconium alloy billet hot-rolled plate; (2) Cool the zirconium alloy sheet after billet rolling to room temperature by air cooling; (3) Perform β-zone heat treatment on the hot-rolled zirconium alloy sheet cooled to room temperature, with a heat treatment temperature of T = (T β +50)℃, heat treatment time is 100min, time until temperature reaches the target temperature; (4) The zirconium alloy plate obtained by the above high temperature heat treatment is directly quenched, with water temperature ≤ 40℃ and immersion time ≤ 20s, until it is cooled to room temperature. (5) The quenched zirconium alloy sheet is subjected to medium-low temperature rolling at a rolling temperature of T=(T β -380)℃, rolling reduction rate 70%; (6) The zirconium alloy sheet obtained by the above-mentioned medium-low temperature rolling is air-cooled to room temperature, and then subjected to heat treatment at a temperature T=(T β The temperature was set at -330℃ for 60 minutes. After the temperature was reached, the plate was air-cooled to room temperature to obtain an ultrafine crystalline zirconium alloy plate.

[0039] Example 2 (1) A zirconium alloy slab (model: R60702) with a thickness of 200 mm is placed on a hot rolling mill for roughing rolling. The rolling temperature is T = (T β-140)℃, rolling reduction rate of 60%, to obtain zirconium alloy billet hot-rolled plate; (2) Air cool the zirconium alloy sheet after the billet rolling to room temperature; (3) The hot-rolled zirconium alloy sheet cooled to room temperature is subjected to near-β zone heat treatment at a temperature of T = (T β -40)℃, heat treatment time 80min; (4) The zirconium alloy plate that has undergone high-temperature heat treatment is directly quenched, with water temperature ≤ 40℃ and immersion time ≤ 20s, until it is cooled to room temperature; (5) The quenched zirconium alloy sheet is subjected to medium-low temperature rolling at a rolling temperature of T=(T β -380)℃, rolling reduction rate 60%; (6) The zirconium alloy sheet rolled at the above medium and low temperature is air-cooled to room temperature, and then subjected to heat treatment at a temperature T = (T β The temperature was set at -300℃ for 50 minutes. After the temperature was reached, the plate was air-cooled to room temperature to obtain an ultrafine crystalline zirconium alloy plate.

[0040] Example 3 (1) A zirconium alloy slab (model: R60702) with a thickness of 220 mm is placed on a hot rolling mill for roughing rolling. The rolling temperature T = (T β At -130)℃, a rolling reduction of 50% was used to obtain a zirconium alloy billet hot-rolled plate; (2) Air cool the zirconium alloy sheet after the billet rolling to room temperature; (3) The hot-rolled zirconium alloy sheet cooled to room temperature is subjected to near-β zone heat treatment at a temperature of T = (T β -10)℃, heat treatment time is 120min, time until temperature reaches the target temperature; (4) The zirconium alloy plate that has undergone high-temperature heat treatment is directly quenched, with water temperature ≤ 40℃ and immersion time ≤ 20s, until it is cooled to room temperature; (5) The quenched zirconium alloy sheet is subjected to medium-low temperature rolling at a rolling temperature of T=(T β -380)℃, rolling reduction 70%; (6) The zirconium alloy sheet rolled at the above medium and low temperature is air-cooled to room temperature, and then subjected to heat treatment at a temperature T = (T β The temperature was set at -330℃ for 70 minutes. After the temperature was reached, the material was air-cooled to room temperature to obtain an ultrafine crystalline zirconium alloy plate.

[0041] Example 4 (1) A zirconium alloy slab (model: R60702) with a thickness of 200 mm is placed on a hot rolling mill for roughing rolling. The rolling temperature is T = (T βAt -130)℃, a rolling reduction of 45% was used to obtain a zirconium alloy billet hot-rolled plate; (2) Cool the zirconium alloy sheet after billet rolling to room temperature by air cooling; (3) The hot-rolled zirconium alloy sheet cooled to room temperature is subjected to high-temperature heat treatment in the β zone, and the heat treatment temperature is T=(T β +30)℃, heat treatment time is 100min, time until temperature reaches the target temperature; (4) The zirconium alloy plate that has undergone high-temperature heat treatment is directly quenched, with water temperature ≤ 40℃ and immersion time ≤ 20s, until it is cooled to room temperature; (5) The quenched zirconium alloy sheet is subjected to medium-low temperature rolling at a rolling temperature of T=(T β -380)℃, rolling reduction 75%; (6) The zirconium alloy sheet rolled at the above medium and low temperature is air-cooled to room temperature, and then subjected to heat treatment at a temperature T = (T β The temperature was set at -330℃ for 60 minutes. After the temperature was reached, the plate was air-cooled to room temperature to obtain an ultrafine crystalline zirconium alloy plate.

[0042] Example 5 Zirconium material was prepared according to the method of Example 1, except that in step (5), the rolling temperature was (T β -350)℃.

[0043] Example 6 Zirconium material was prepared according to the method of Example 1, except that in step (5), the rolling temperature was (T β -330)℃.

[0044] Example 7 Zirconium materials were prepared according to the method in Example 1, except that “R60702 zirconium alloy slab” was replaced with “R60700 zirconium alloy slab”, and the results are shown in Table 1.

[0045] Example 8 Zirconium material was prepared according to the method in Example 1, except that "thickness specification of 200 mm" was replaced with "thickness specification of 160 mm", and the results are shown in Table 1.

[0046] Example 9 Zirconium material was prepared according to the method of Example 1, except that the rolling reduction rate in step (1) was 70%.

[0047] Example 10 Zirconium material was prepared according to the method in Example 1, except that the heat treatment time in step (3) was 50 min.

[0048] Example 11 Zirconium material was prepared according to the method of Example 1, except that in step (5), the rolling reduction rate was 50%.

[0049] Example 12 Zirconium material was prepared according to the method of Example 1, except that in step (4), the cooling method was air cooling.

[0050] Example 13 Zirconium material was prepared according to the method of Example 1, except that the cooling method in step (4) was replaced with air cooling.

[0051] Comparative Example 1 Zirconium material was prepared according to the method of Example 1, except that steps (3) and (4) were not performed.

[0052] Comparative Example 2 Zirconium material was prepared according to the method of Example 1, except that in step (3), the heat treatment temperature was (T β -70)℃.

[0053] Comparative Example 3 Zirconium material was prepared according to the method of Example 1, except that in step (5), the rolling temperature was (T β -180)℃.

[0054] Comparative Example 4 Zirconium material was prepared according to the method of Example 1, except that steps (3) and (4) were omitted; and in step (5), the rolling temperature was (T β -180)℃.

[0055] Comparative Example 5 Zirconium material was prepared according to the method of Example 7, except that steps (3) and (4) were not performed.

[0056] Test Example 1 The tensile strength, yield strength and elongation of the zirconium materials obtained in the examples and comparative examples were tested according to the method in GB / T 228.1-2021, and the results are shown in Table 1.

[0057] Table 1 Mechanical properties of the embodiments and comparative examples

[0058] As can be seen from the results in Table 1, compared with Comparative Examples 1-5, the zirconium materials prepared by the method provided in this invention in Examples 1-13 have excellent mechanical properties.

[0059] Test Example 2 The metallographic structure and average grain size of the zirconium plate and the finally obtained zirconium material in step (4) of Example 1, the zirconium plate and the finally obtained zirconium material in step (4) of Example 3, and the finally obtained zirconium material in Comparative Example 5 were tested according to the methods in GB / T 13298 and GB / T 6394-2017. Figures 1-5 As shown. Among them, Figure 1 The metallographic image of the zirconium alloy plate obtained after step (4) of Example 1 shows that the microstructure is lamellar, and the initial β phase is completely transformed into lamellar structure during the cooling process. Figure 2 The image shows the metallographic structure of the zirconium alloy plate obtained after step (4) in Example 3. The microstructure exhibits a combination of lamellar and equiaxed structures. Figure 3 The image shows the metallographic structure of the zirconium alloy plate finally obtained in Example 1; the microstructure consists of uniformly distributed ultrafine equiaxed grains with an average grain size of 4.75 μm. Figure 4 The image shows the metallographic structure of the zirconium alloy plate finally obtained in Example 3. The microstructure consists of uniformly distributed ultrafine equiaxed grains with an average grain size of 6.84 µm. Figure 5 The image shows the metallographic structure of the zirconium alloy plate finally obtained in Comparative Example 4. The microstructure is also recrystallized grains, but the average grain size is 8.50 µm.

[0060] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing zirconium material, characterized in that, The preparation method includes: performing a roughing and rolling process I on a zirconium-containing forged slab to obtain a billet, and then performing heat treatment I, rolling process II, and heat treatment II on the billet; The temperature of heat treatment I is (T) β -40)~(T β +50)℃; The temperature of the rolling process II is (T) β -430)~(T β -330)℃; The temperature of the heat treatment II is (T) β -380)~(T β -280)℃; The zirconium-containing forged slab is a slab of R60702 zirconium alloy and / or a slab of R60700 zirconium alloy. The preparation method further includes: quenching the billet before the rolling process II; the conditions for the initial rolling process I include: a temperature of (T... β -150)~(T β -130)℃, rolling reduction rate of 40-60%; the rolling reduction rate of rolling treatment II is 60-75%.

2. The preparation method according to claim 1, characterized in that, The thickness of the zirconium-containing forged slab is 160-220 mm.

3. The preparation method according to claim 1 or 2, characterized in that, The heat treatment time is 80-120 min.

4. The preparation method according to claim 1, characterized in that, The preparation method further includes: cooling the billet after rolling process II.

5. The zirconium material prepared by the preparation method according to any one of claims 1 to 4, characterized in that, The microstructure of the zirconium material is an equiaxed crystal structure with a diameter of 4.75-6.84 μm.

6. The zirconium material according to claim 5, characterized in that, The zirconium material has a tensile strength of 394-500 MPa, a yield strength of 288-370 MPa, and an elongation of 26-40%.

7. The application of the zirconium material according to claim 5 or 6 in the fields of petrochemical, nuclear industry and aerospace.

Images