A zirconium alloy strip and a texture control method and application thereof

Abstract

The application discloses a zirconium alloy strip and a texture control method and application thereof. The zirconium alloy strip is obtained by adopting (alpha+beta) two-phase zone temperature (700 DEG C-850 DEG C) hot rolling or direct hot rolling under alpha phase zone hot rolling conditions, adopting cross rolling under the condition of one-time hot rolling under the alpha phase zone hot rolling conditions, and performing quenching treatment after one-time hot rolling under the alpha phase zone hot rolling conditions, so that the texture of the zirconium alloy strip is effectively controlled, the texture orientation factor is equivalent to that of imported Zr-4, and the performance requirement of the zirconium alloy strip is met.

Description

Technical Field

[0001] This invention relates to the field of special material preparation technology, specifically to a zirconium alloy strip and its texture control method and application. Background Technology

[0002] Fuel assemblies are key core components of nuclear fission reactors, operating under conditions of high radiation, high temperature, and high pressure for extended periods. The positioning grid is a crucial component of the nuclear fuel assembly, playing a vital role in maintaining lateral spacing between fuel rods, mixing the coolant, and optimizing the reactor core's thermal-hydraulic properties. It is one of the key components determining the performance of the fuel assembly. Zirconium alloys, with their low neutron absorption cross-section and excellent mechanical and corrosion resistance in high-temperature, high-pressure water, have been widely used in reactor fuel assemblies, serving as key components such as fuel rod cladding, assembly positioning grids, and guide tubes in water-cooled power reactors. To improve the neutron economy of nuclear reactors, many advanced developed countries worldwide are vigorously developing the use of zirconium alloys to replace the initially used stainless steel or Inconel materials as grid materials, gradually achieving the use of all-zirconium assemblies.

[0003] CN101270425A discloses a high-performance zirconium alloy based on the Zr-Sn-Nb system (nominal composition Zr-1Sn-1Nb-0.3Fe). The industrial-scale development of cladding tubes and end plug rods for fuel assemblies has been completed, and its engineering application in reactors has been realized. The use of high-performance new zirconium alloys as grid materials represents a technological development trend in advanced international nuclear power reactor fuel assemblies.

[0004] Zirconium alloys at room temperature are hexagonal close-packed α-phase. Due to the limited number of slip systems in hcp structure metallic crystals, deformation at room temperature is accomplished by both slip and twinning. α-Zr readily exhibits a distinct preferred grain orientation during processing, resulting in a strong texture. The interplanar spacing and atomic density axial ratio of zirconium (…) The atomic density of α-Zr is 1.593, meaning its prismatic faces have a higher average atomic density than its basal faces, making dislocations more prone to slip on these faces. The prismatic faces of α-Zr include... cylindrical and facets, in which The cylindrical slip system is the primary deformation system of zirconium. At low temperatures, The critical shear stress required for slip is very high, and the deformation of zirconium alloys is mainly achieved through... and The twinning is complete. As the temperature rises, The critical shear stress of the slip system is significantly reduced, and the number of slip systems that can be initiated increases (including basal slip and conical slip), only The slip system can provide two and four independent slip systems respectively, which can meet the requirements of continuous and coordinated deformation of polycrystalline materials, thus reducing the contribution of twins to deformation.

[0005] The texture of cold-rolled and hot-rolled plates in the α-phase temperature zone, viewed from the (0002) pole figure, shows that most grains have their

[0002] axes distributed on the ND-TD plane (ND - rolling surface normal, TD - transverse), deviating less than 30° towards the RD direction (RD - rolling direction), mainly concentrated in the central part of the pole figure (ND direction). Texture orientation factor f x This refers to the orientation component of the

[0002] base poles of all grains in a zirconium alloy along the characteristic appearance direction. For sheet and strip materials, the characteristic appearance direction refers to the rolling surface normal, transverse, and rolling direction, and the texture orientation factor in these three directions is represented by f. n f t and f l express.

[0006] For zirconium alloys, although their main slip and twinning systems are known, slip and twinning effects are related to the temperature of metal processing, the mode of stress, the grain size of the material, the types of alloying elements, and whether phase transformation occurs. Therefore, the texture formed by different zirconium alloys through different processing processes follows certain patterns, but also has its own unique characteristics. The texture of zirconium alloys not only affects many mechanical property parameters, such as mechanical strength, plasticity, creep, and fatigue, but also relates to irradiation growth, stress corrosion cracking, and water-side corrosion resistance. Therefore, texture research and control play a very important role in the development and utilization of zirconium alloys.

[0007] The texture of zirconium alloy strips is closely related to the processing technology. Rolling temperature, deformation amount, heat treatment regime, etc. will all affect the texture. However, there are few reports on the influence of these factors on the texture of Zr-Sn-Nb alloy strips (i.e. zirconium alloy strips). Summary of the Invention

[0008] The technical problem to be solved by this invention is the influence of rolling temperature, deformation amount, and heat treatment regime on the texture of Zr-Sn-Nb alloy strip.

[0009] The first objective of this invention is to provide a method for controlling the texture of zirconium alloy strip, comprising:

[0010] The pretreated zirconium alloy forging billet was hot rolled in two passes, and then annealed at 600℃~650℃ for 1~3h to obtain zirconium alloy slab 1.

[0011] The zirconium alloy slab 1 is cold rolled at least once, with a cold rolling deformation of 55% to 80%, and then vacuum annealed at 600 to 650°C for 1 to 3 hours to obtain zirconium alloy slab 2.

[0012] The zirconium alloy slab 2 is precision rolled with a deformation of 45%~75%, and then annealed at 600℃~650℃ for 5~20 minutes.

[0013] When the above technical solution is adopted,

[0014] The zirconium alloy strip obtained by this invention has the following relationship in the rolling surface normal, transverse, and rolling direction: f n >f t >f l f n +f t +f l =1, f t A texture orientation factor of ≥0.15 indicates typical base electrode texture characteristics. The texture orientation factor of the zirconium alloy strip is comparable to that of imported Zr-4 strip, exhibiting good plasticity and excellent stamping performance in strip stamping tests. It can be used as a material for manufacturing strips for nuclear reactor fuel assemblies.

[0015] As a possible design, when performing two-pass hot rolling within the α+β two-phase range, the first and second hot rolling temperatures are both 700℃~760℃, with the former holding for 40min~60min and the latter holding for 20min~40min. The deformation per pass is controlled within the range of 60%~90%. The f value of the zirconium alloy slab 1 is... t With a value of ≥0.3, the texture of the zirconium alloy strip was effectively controlled.

[0016] As a possible design, when performing two-pass hot rolling within the α+β two-phase range, the first and second hot rolling temperatures are both 760℃~850℃, with the former holding for 40min~60min and the latter holding for 20min~40min. The deformation per pass is controlled within the range of 60%~90%. The f value of the zirconium alloy slab 1 is... t With a value of ≥0.3, the texture of the zirconium alloy strip was effectively controlled.

[0017] As one possible design, during the two-pass hot rolling in the α-phase region, the first hot rolling pass employs cross rolling. The texture of the zirconium alloy strip is effectively controlled.

[0018] As one possible design, the temperatures for both the primary and secondary hot rolling are 580℃~650℃, with a holding time of 20min~60min. The deformation in each pass of the primary and secondary hot rolling is controlled within the range of 60%~90%. The rolling direction of the primary hot rolling is perpendicular to the forging direction. The f of the zirconium alloy slab 1... t ≥0.2. The texture of the zirconium alloy strip was effectively controlled.

[0019] As one possible design, during two-pass hot rolling in the α-phase region, the first hot rolling is followed by quenching, and then a second hot rolling is performed. The quenching temperature is 1045℃~1095℃, and the quenching time is 40min~60min. The zirconium alloy slab 1 exhibits f... t ≥0.3. The texture of the zirconium alloy strip was effectively controlled.

[0020] As one possible design, the temperatures for both the first and second hot rolling processes are 580℃~650℃, with a holding time of 20min~60min. This effectively controls the texture of the zirconium alloy strip.

[0021] As a possible design, the deformation amount of each hot rolling pass in the primary and secondary hot rolling processes is controlled within the range of 60% to 90%. The texture of the zirconium alloy strip is effectively controlled. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0023] For zirconium alloys, although their main slip and twinning systems are known, slip and twinning effects are related to the temperature of metal processing, the mode of stress, the grain size of the material, the types of alloying elements, and whether phase transformation occurs. Therefore, the texture formed by different zirconium alloys through different processing processes follows certain patterns, but also has its own unique characteristics. The texture of zirconium alloys not only affects many mechanical property parameters, such as mechanical strength, plasticity, creep, and fatigue, but also relates to irradiation growth, stress corrosion cracking, and water-side corrosion resistance. Therefore, texture research and control play a very important role in the development and utilization of zirconium alloys.

[0024] This invention addresses the shortcomings of existing technologies in analyzing factors that affect texture, such as rolling temperature, deformation amount, and heat treatment process, thereby enabling more effective control of the texture of zirconium alloy strips.

[0025] This invention controls the texture orientation factor of the hot-rolled sheet material and also studies the influence of the hot-rolled phase region and hot-rolling method on the texture orientation factor of the hot-rolled sheet material, ultimately used to control the product quality of zirconium alloy strip.

[0026] This invention discloses a method for controlling the texture of zirconium alloy strip, comprising the following steps:

[0027] S1. The pretreated zirconium alloy forging billet is hot rolled in two passes, and then annealed at 600℃~650℃ for 1~3h to obtain zirconium alloy slab 1.

[0028] S2. The zirconium alloy slab 1 is subjected to at least one cold rolling pass with a cold rolling deformation of 55%~80%, and then vacuum annealed at 600℃~650℃ for 1~3h to obtain zirconium alloy slab 2.

[0029] S3. The zirconium alloy slab 2 is precision rolled with a deformation of 45%~75%, and then annealed at 600℃~650℃ for 5min~20min.

[0030] By selecting a specific hot-rolling region and the annealing temperature and time after hot rolling, the f of the obtained zirconium alloy slab 1 t Meeting certain conditions is beneficial for controlling the microstructure of the final zirconium alloy strip, while also obtaining zirconium alloy strip that meets performance requirements.

[0031] In step S1, the zirconium alloy forging billet can be directly subjected to two-pass hot rolling (i.e., it needs to be carried out within a specific phase region). The hot rolling temperature is 580℃~650℃, and the holding time is 20min~60min. The deformation amount of each hot rolling pass is controlled at 60%~90%. The f of the zirconium alloy slab 1 t ≥0.2. The holding time is selected based on the hot rolling temperature and the amount of deformation.

[0032] In step S1, the zirconium alloy forging billet can be hot rolled in two passes in a specific phase region, for example, two passes in the α+β two-phase region or two passes in the α phase region.

[0033] When performing two-pass hot rolling within the α+β two-phase range, the temperatures for both the first and second hot rolling passes are 700℃~760℃. The holding time for the first pass is 40min~60min, and for the second pass, it is 20min~40min. The deformation in each hot rolling pass is controlled within the range of 60%~90%. The zirconium alloy slab 1 obtained by this hot rolling method exhibits f... t ≥0.3, which shows that this method is beneficial for controlling the microstructure of zirconium alloy slab 1.

[0034] When performing two-pass hot rolling within the α+β two-phase range, the temperatures for both the first and second hot rolling passes are 760℃~850℃. The holding time for the first pass is 40min~60min, and for the second pass, it is 20min~40min. The deformation amount in each hot rolling pass is controlled within the range of 60%~90%. The f value of the zirconium alloy slab 1... t ≥0.3. This indicates that when the hot rolling temperature is within a relatively wide range, the microstructure of the obtained zirconium alloy slab 1 is effectively controlled.

[0035] When performing two-pass hot rolling in the α-phase region, the first hot rolling adopts cross rolling, followed by quenching treatment, and then a second hot rolling. The quenching temperature is 1045℃~1095℃, and the quenching time is 40min~60min. The zirconium alloy slab 1 has a f... t ≥0.3. The temperatures for both the first and second hot rolling passes are 580℃~650℃, with a holding time of 20min~60min. The deformation in each hot rolling pass is controlled within the range of 60%~90%. The final zirconium alloy strip meets the following conditions: f n >f t >f l f n +f t +f l =1, where f t ≥0.15. Example

[0036] The pretreated zirconium alloy forging billet was hot rolled twice at a temperature of 580℃ for 60 min, with the deformation controlled at 60% in each pass, to obtain hot-rolled sheet. It was then cold-rolled once with a deformation of 80%, and then vacuum annealed at 600℃ for 3 h. The cold-rolled sheet was then finished by precision rolling (60% deformation) and annealed at 620℃ for 12 min to obtain N36 zirconium alloy finished strip. The texture analysis results are shown in Table 1.

[0037]

[0038] Example 2

[0039] Hot rolling was performed at 780℃ within the α+β two-phase temperature range, with a holding time of 60 min. The deformation in each hot rolling pass was controlled at 60%, resulting in hot-rolled sheet. This was followed by two passes of cold rolling with a deformation of 80%, and then vacuum annealing at 650℃ for 3 h. The cold-rolled sheet underwent finish rolling (45% deformation) and final annealing at 650℃ for 20 min to produce finished strip. Texture analysis of the finished strip was performed, and the results are shown in Table 2.

[0040]

[0041] Example 3

[0042] Hot rolling was performed in the α-phase region at a temperature of 580℃ for both the first and second hot rolling processes. After the first hot rolling, the strip was quenched at 1070℃ for 40 min, followed by a second hot rolling process with a holding time of 60 min, and then cold rolling in one pass with a cold rolling deformation of 66%. After cold rolling, the strip underwent vacuum annealing at 620℃ for 1.5 h, finishing, and final annealing to produce the finished strip. Texture analysis of the finished strip was performed, and the results are shown in Table 3.

[0043]

[0044] Example 4

[0045] Hot rolling was performed in the α-phase region, with cross-rolling in the first and second hot rolling processes. The temperature of both the first and second hot rolling processes was 580℃. After the second hot rolling, the strip was held at that temperature for 60 min and then cold rolled in one pass with a cold rolling deformation of 66%. After cold rolling, the strip underwent vacuum annealing at 620℃ for 1.5 h, finishing, and final annealing to produce the finished strip. Texture analysis of the finished strip was performed, and the results are shown in Table 4.

[0046]

[0047] Example 5

[0048] Hot rolling was performed at 720℃ within the α+β two-phase temperature range, with a holding time of 50 min. The deformation in each hot rolling pass was controlled at 80%, resulting in hot-rolled sheet. This was followed by one pass of cold rolling with a deformation of 70%, and then vacuum annealing at 600℃ for 1 h. The cold-rolled sheet underwent finish rolling (70% deformation) and finishing annealing at 620℃ for 8 min to produce finished strip. Texture analysis of the finished strip was performed, and the results are shown in Table 5.

[0049]

[0050] Example 6

[0051] The pretreated zirconium alloy forging was hot rolled in two passes at a temperature of 580℃ and a holding time of 60 min, with the deformation controlled at 60% in each pass. Then, it was quenched at 1068℃ to obtain a hot-rolled sheet. It was then cold-rolled in one pass with a deformation of 80%, and then vacuum annealed at 600℃ for 1 h. The cold-rolled sheet was then finished by precision rolling (deformation of 55%) and annealing at 630℃ for 10 min to obtain N36 zirconium alloy finished strip. The texture analysis results are shown in Table 6.

[0052]

[0053] As can be seen from Examples 1-6, by using hot rolling at a temperature of 700℃~850℃ in the (α+β) two-phase range during the hot rolling stage, or by direct hot rolling under α phase hot rolling conditions, by using cross rolling for one-time hot rolling under α phase hot rolling conditions, and by performing quenching treatment after one-time hot rolling under α phase hot rolling conditions, the texture of zirconium alloy strip is effectively controlled, and the texture orientation factor is comparable to that of imported Zr-4, thus meeting the performance requirements of zirconium alloy strip.

[0054] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling the texture of N36 zirconium alloy strip, characterized in that, The texture control method includes: The pretreated zirconium alloy forging billet was hot rolled in two passes, and then annealed at 600℃~650℃ for 1~3h to obtain zirconium alloy slab 1. The zirconium alloy slab 1 is cold rolled at least once, with a cold rolling deformation of 55% to 80%, and then vacuum annealed at 600℃ to 650℃ for 1 to 3 hours to obtain zirconium alloy slab 2. The zirconium alloy slab 2 is precision rolled with a deformation of 45%~75%, and then annealed at 600℃~650℃ for 5~20min. When performing two-pass hot rolling within the α+β two-phase range, the temperature for both the first and second hot rolling passes is 700℃~760℃. The holding time for the first pass is 40min~60min, and for the second pass, it is 20min~40min. The deformation amount in each hot rolling pass is controlled within the range of 60%~90%. The f value of the zirconium alloy slab 1... t ≥0.3; or When performing two-pass hot rolling within the α+β two-phase range, the temperatures of both the first and second hot rolling passes are greater than 760℃ and less than or equal to 850℃. The holding time for the first pass is 40-60 minutes, and for the second pass, it is 20-40 minutes. The deformation amount in each hot rolling pass is controlled within the range of 60%-90%. The f value of the zirconium alloy slab 1... t ≥0.3; or When performing two-pass hot rolling in the α-phase region, the first hot rolling is performed using cross rolling. The temperatures for both the first and second hot rolling processes are 580℃~650℃, with a holding time of 20min~60min. The deformation amount in each pass of the first and second hot rolling processes is controlled within the range of 60%~90%. The rolling direction of the first hot rolling process is perpendicular to the forging direction. The f value of the zirconium alloy slab 1... t ≥0.2; When performing two-pass hot rolling in the α-phase region, the first hot rolling is followed by quenching, and then a second hot rolling is performed. The quenching temperature is 1045~1095℃, and the quenching time is 40min~60min. The zirconium alloy slab 1 has a f... t ≥0.

3.

2. A texture control method according to claim 1 for obtaining N36 zirconium alloy strip, characterized in that, f of the zirconium alloy strip n >f t >f l f n +f t +f l =1, where f t ≥0.

15.

3. An application of the N36 zirconium alloy strip as described in claim 2 in the nuclear field, characterized in that, The zirconium alloy strip is used to fabricate the core structure of a nuclear power reactor.

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