Rolling method of R60705 zirconium alloy medium plate

Abstract

The invention discloses a rolling method of an R60705 zirconium alloy medium-thickness plate. The rolling method comprises the following steps: 1, carrying out four-fire forging on an R60705 zirconium alloy ingot to obtain a forged plate blank; secondly, the forged plate blank is heated and then subjected to first heating number rolling, and a first rolled plate blank is obtained; 3, cutting after polishing; 4, after heating, carrying out second heating number rolling to obtain a second rolled plate blank; 5, cutting after polishing; 6, heating the second intermediate plate blank, and rolling the second intermediate plate blank at a third heating number to obtain a third rolled plate blank; seventhly, the first rolled plate blank, the second rolled plate blank or the third rolled plate blank is subjected to annealing treatment and straightening; and 8, polishing, shearing and pickling a finished product. According to the method, the anisotropy of the mechanical property of the plate is reduced through reasonable distribution of the transverse deformation amount and the longitudinal deformation amount, the rolling temperature, the rolling heating number, the rolling deformation rate, the annealing temperature and other technological parameters are comprehensively controlled, and the R60705 medium-thickness plate which is suitable for the field of chemical engineering structures and good in strong plasticity matching is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of zirconium and zirconium alloy medium and thick plates preparation, and specifically relates to a method for rolling R60705 zirconium alloy medium and thick plates. Background Art

[0002] Zirconium and zirconium alloys have excellent nuclear properties, good resistance to high temperature and water vapor corrosion, and are widely used in nuclear power engineering. Industrial-grade zirconium and zirconium alloys have excellent corrosion resistance and thermal conductivity in many organic acids, inorganic acids, strong alkalis and molten salts, and are excellent chemical corrosion-resistant structural materials. R60705 zirconium alloy is an industrial-grade zirconium alloy with about 2.0% to 3.0% Nb added. Nb can improve the strength and corrosion resistance of zirconium.

[0003] Common industrial-grade zirconium alloys such as R60700 and R60702 have relatively mature processes, with fewer alloying elements added, and their stable organization is completely single-phase α grains. However, after adding about 2.0% to 3.0% Nb elements, the stability of the β phase of R60705 zirconium alloy is significantly enhanced, which is significantly different from R60700 and R60702. Therefore, its processing technology should also be revised accordingly according to its characteristics, and cannot be processed completely according to the R60700 and R60702 processes. Therefore, technical improvements are urgently needed. Combining the characteristics of zirconium alloys and the characteristics of general two-phase alloys, it is key to obtain uniform two-phase organization, excellent strength matching, and R60705 zirconium alloy medium and thick plates with small differences in transverse and longitudinal mechanical properties. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for rolling R60705 zirconium alloy medium and thick plates in view of the above-mentioned deficiencies in the prior art. The method comprehensively controls the process parameters of rolling temperature, rolling fire, rolling deformation rate and annealing temperature, fully and evenly destroys the internal structure, improves the deformation uniformity of rolling, and reduces the anisotropy of the mechanical properties of the plate, thereby obtaining R60705 zirconium alloy medium and thick plates with uniform two-phase structure, excellent strength-plasticity matching and small difference in transverse and longitudinal mechanical properties, thus solving the problem of the lack of R60705 zirconium alloy medium and thick plate processing technology in the prior art.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for rolling R60705 zirconium alloy medium and thick plates, characterized in that the method comprises the following steps:

[0006] Step 1, blank making: the R60705 zirconium alloy ingot is subjected to four-fire forging, and the cooling method after each fire forging is air cooling, and then the surface oxide scale is removed by grinding, and ultrasonic flaw detection is performed after the grinding of the fourth fire forging, and the result must meet the A1 level requirements of GB / T5193-2007 "Ultrasonic flaw detection method for titanium and titanium alloy processed products", and pass the appearance size and surface quality inspection to obtain the R60705 zirconium alloy forging blank; the R60705 zirconium alloy forging blank has a thickness of 160mm to 240mm, a width of 800mm to 2400mm, and a length of more than 800mm;

[0007] Step 2, blank heating and blank rolling: coating the surface of the R60705 zirconium alloy forged slab obtained in step 1 with an anti-oxidation coating, then heating and performing the first fire rolling, and obtaining the first rolled slab after cooling; the first fire rolling has a pass deformation rate of 4% to 23%, and the number of passes is 8 to 14; the first rolled slab has a thickness of 20 mm to 80 mm, and a width of 800 mm to 2400 mm;

[0008] Step 3, semi-finished product grinding and second-fire blanking: the first rolled slab obtained in step 2 is ground to remove the surface oxide scale, and then cut to obtain a plurality of first intermediate slabs; the first intermediate slabs have a thickness of 20 mm to 80 mm and a length of 800 mm to 2400 mm;

[0009] Step 4, second-fire heating and second-fire rolling: The first intermediate slab obtained in step 3 is heated and rolled for the second time, and combined with online reheating to obtain a second rolled slab; the deformation rate of the second rolling is 10% to 25%, the number of passes is 3 to 6, and the rolling direction of the second rolling is perpendicular to the rolling direction of the first rolling in step 2; the thickness of the second rolled slab is 8 mm to 40 mm, and the width is 800 mm to 2400 mm;

[0010] Step 5, semi-finished product grinding and three-fire blanking: the second rolled slab obtained in step 4 is ground to remove the surface oxide scale, and then cut to obtain a plurality of second intermediate slabs; the thickness of the second intermediate slab is 8 mm to 40 mm, and the length or width is 800 mm to 2400 mm;

[0011] Step 6, three-fire heating and three-fire rolling: The second intermediate slab obtained in step 5 is heated and rolled for the third time to obtain a third rolled slab; the pass deformation rate of the third rolling is 10% to 25%, the number of passes is 3 to 6, and the rolling direction of the third rolling is parallel or perpendicular to the rolling direction of the second rolling in step 4; the thickness of the third rolled slab is 4 mm to 20 mm, and the width is 800 mm to 2400 mm;

[0012] Step 7, annealing and straightening of finished products: annealing and straightening the first rolled slab obtained in step 2, the second rolled slab obtained in step 4, or the third rolled slab obtained in step 6, and cooling to obtain R60705 zirconium alloy medium-thick slab; the R60705 zirconium alloy medium-thick slab has a thickness of 4 mm to 80 mm and a width of 800 mm to 2400 mm;

[0013] Step 8: Finished product grinding, shearing and pickling: The R60705 zirconium alloy medium and thick plate blank obtained in step 7 is ground to remove the surface oxide scale, and is ground to the required thickness of the finished product, and then sheared to the required length and width of the finished product, and then pickled to obtain the finished R60705 zirconium alloy medium and thick plate; the finished R60705 zirconium alloy medium and thick plate has a thickness of 4 mm to 80 mm and a width of less than 2400 mm.

[0014] The above-mentioned method for rolling a medium and thick plate of R60705 zirconium alloy is characterized in that, during the four-fire forging process described in step 1, the heating temperature of the first fire forging and the second fire forging is 1000°C to 1050°C, the initial forging temperature is above 900°C, and the final forging temperature is above 700°C, and the heating temperature of the third fire forging and the fourth fire forging is 950°C to 1000°C, the initial forging temperature is above 850°C, and the final forging temperature is above 700°C. The present invention controls the heating temperature of the first fire forging and the second fire forging to be above the β phase transformation point, so that the original grains of the cast state are more fully and evenly broken, and controls the heating temperature of the third fire forging and the fourth fire forging to be near the β phase transformation point, so that the forged slab obtains a fine and uniform internal structure, and achieves a good strength-plasticity match.

[0015] The above-mentioned method for rolling a medium and thick plate of R60705 zirconium alloy is characterized in that the specific process of the first fire rolling in step 2 is: carried out at a temperature of 900°C to 940°C, combined with online reheating, the total deformation rate of the first fire rolling is 60% to 90%; the first fire rolling is widening rolling or unidirectional rolling, and the thickness of the finished R60705 zirconium alloy medium and thick plate directly prepared by the first fire rolling is 20mm to 80mm, Among them, when the thickness of the finished R60705 zirconium alloy medium and thick plate is 20mm~40mm and the finished product is obtained by one round of rolling, widening rolling is selected: the heated R60705 zirconium alloy forging slab is first rolled to 1.2~1.4 times of the original length, then rotated 90°, and combined with online remelting and warming rolling to the target thickness, when the size of the widened rolled slab exceeds the processing range of the rolling mill or a plurality of plates of different thicknesses are obtained by rolling a piece of forged slab, multiple rounds of rolling are selected to obtain the finished product.

[0016] The present invention controls the temperature of the first rolling to be in the high temperature zone of the α+β two-phase region, and combines online reheating to compensate for the temperature, which is beneficial to achieving a large deformation amount of the open-blanking rolling, so that the first intermediate slab obtains a fine and uniform internal structure; at the same time, by formulating rolling strategies for finished products of different thicknesses, the anisotropy of the R60705 zirconium alloy medium and thick plates is greatly reduced, and the structural uniformity of the R60705 zirconium alloy plates is improved.

[0017] The above-mentioned method for rolling medium and thick plates of R60705 zirconium alloy is characterized in that the specific process of the second rolling in step 4 is: carried out at a temperature of 860°C to 880°C, and combined with online reheating and heating, the total deformation rate of the second rolling is 45% to 65%.

[0018] The present invention controls the temperature of the second fire rolling to be in the middle temperature zone of the α+β two-phase zone, which is beneficial to improving the yield rate, while reducing the influence of the phase change texture on the mechanical properties, and keeps the second fire rolling perpendicular to the first fire rolling direction, controls the pass deformation rate and the total deformation rate of the two to be close, greatly reduces the anisotropy of the mechanical properties of the R60705 zirconium alloy medium and thick plate, and improves the organizational uniformity of the R60705 zirconium alloy medium and thick plate.

[0019] The above-mentioned method for rolling medium and thick plates of R60705 zirconium alloy is characterized in that the specific process of the third rolling in step six is: carried out at a temperature of 840°C to 860°C, and the total deformation rate of the third rolling is 40% to 55%.

[0020] The above-mentioned method for rolling R60705 zirconium alloy medium and thick plates is characterized in that the specific process of annealing treatment in step seven is: keeping warm at a temperature of 700°C to 800°C for (H+30~H+60)min, H is the thickness of the annealed slab, in mm, and hot straightening by a roller straightener after being taken out of the furnace to meet the unevenness requirements of the finished product; the cooling is air cooling or air cooling, wherein when the thickness of the finished R60705 zirconium alloy medium and thick plates is greater than 20mm, air cooling to room temperature is selected, and when the thickness of the finished R60705 zirconium alloy medium and thick plates does not exceed 20mm, air cooling to room temperature is selected. The present invention improves the elongation of the R60705 zirconium alloy medium and thick plates by controlling the product annealing temperature, while avoiding the sharp decline of its tensile strength and yield strength, so that the R60705 zirconium alloy medium and thick plates obtain better strength-plasticity matching.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. The present invention adopts four-fire forging to obtain R60705 zirconium alloy forging slabs. By controlling the heating temperatures of the first fire forging and the second fire forging to be above the β phase transformation point, the original cast grains are more fully and evenly crushed. By controlling the heating temperatures of the third fire forging and the fourth fire forging to be near the β phase transformation point, the forged slabs obtain a fine and uniform internal structure, achieve good strength-plasticity matching, and ensure the smooth progress of the subsequent rolling process.

[0023] 2. When the present invention adopts multi-pass hot rolling, by keeping the second pass rolling perpendicular to the first pass rolling direction and controlling the pass deformation rate and total deformation rate of the two passes to be close, the anisotropy of the mechanical properties of the R60705 zirconium alloy medium and thick plate is greatly reduced, and the organizational uniformity of the R60705 zirconium alloy medium and thick plate is improved, and finally the R60705 zirconium alloy medium and thick plate with uniform two-phase organization, excellent strength-plasticity matching and small difference in transverse and longitudinal mechanical properties is obtained.

[0024] 3. The present invention improves the deformation uniformity of rolling by comprehensively controlling process parameters such as rolling heat, rolling temperature, rolling deformation rate and annealing temperature, thereby improving the uniformity of the structure of R60705 zirconium alloy medium and thick plates, and effectively eliminates the large-sized plate grains produced by forging. In addition, the rolling process is combined with online reheating to reduce the influence of temperature fluctuations on the hot rolling deformation of R60705 zirconium alloy plates, thereby improving the rolling accuracy and stability.

[0025] 4. The present invention improves the elongation of R60705 zirconium alloy medium and thick plates by annealing the rolled slab at a temperature of 700°C to 800°C, while avoiding a sharp drop in its tensile strength and yield strength, so that the R60705 zirconium alloy medium and thick plates obtain a better strength-plasticity match, and combines straightening, grinding, shearing and pickling treatments after annealing to obtain finished R60705 zirconium alloy medium and thick plates with good plate shape and excellent surface quality.

[0026] 5. The present invention has a flexible and varied process route for R60705 zirconium alloy medium and thick plates with a thickness of 4 mm to 40 mm. The slabs obtained by the first and second rolling processes can be cut and processed as intermediate slabs for subsequent rolling processes. The thickness range of the first rolled slab is relatively wide, and a single slab can be selected to be rolled for multiple times to obtain finished products of different specifications, thereby greatly improving the yield rate of R60705 zirconium alloy medium and thick plates.

[0027] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the metallographic structure diagram (200×) of the R60705 zirconium alloy medium and thick plate prepared in Example 1 of the present invention.

[0029] Figure 2 This is the metallographic structure diagram (200×) of the R60705 zirconium alloy medium and thick plate prepared in Example 2 of the present invention.

[0030] Figure 3 This is the metallographic structure diagram (200×) of the R60705 zirconium alloy medium and thick plate prepared in Example 3 of the present invention.

[0031] Figure 4 This is the metallographic structure diagram (200×) of the R60705 zirconium alloy medium and thick plate prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0032] Example 1

[0033] This embodiment includes the following steps:

[0034] Step 1, blank making: subjecting the R60705 zirconium alloy ingot to four-fire forging, wherein the heating temperature of the first fire forging and the second fire forging is 1050°C, the initial forging temperature is 983°C, and the final forging temperature is 742°C, the heating temperature of the third fire forging and the fourth fire forging is 1000°C, the initial forging temperature is 911°C, and the final forging temperature is 749°C, and the cooling method after each fire forging is air cooling, followed by grinding to remove the surface oxide scale, and ultrasonic flaw detection is performed after grinding of the fourth fire forging, and the result must meet the A1 level requirements of GB / T5193-2007 "Ultrasonic Flaw Detection Method for Titanium and Titanium Alloy Processing Products", and pass the appearance size and surface quality inspection to obtain the R60705 zirconium alloy forging slab; the R60705 zirconium alloy forging slab has a thickness of 188 mm, a width of 1000 mm, and a length of 1715 mm;

[0035] Step 2, billet heating and billet rolling: the surface of the R60705 zirconium alloy forging slab obtained in step 1 is coated with an anti-oxidation coating, and then heated to a temperature of 940°C for the first hot rolling, combined with online reheating, and the first rolled slab is obtained after cooling; the first hot rolling is widening rolling, and the pass deformation rates are 9.6%, 10.6%, and 11.8% respectively. The heated R60705 zirconium alloy forging slab is rolled to a length of 2400 mm, and then rotated 90°, and the online reheating is performed. After the furnace is heated for 110 minutes, rolling is continued, and the deformation rates of each pass are 14.2%, 15.7%, 16.5%, 17.3%, and 16.4% in sequence. After the online furnace is heated for 60 minutes, rolling is continued, and the deformation rates of each pass are 17.9%, 17.4%, 18.4%, 19.4%, and 16.0% in sequence. The number of passes is 13, and the total deformation rate is 88.9%. After completion, it is air-cooled to room temperature; the thickness of the first rolled slab is 20 mm, the width is 2400 mm, and the length is 5650 mm;

[0036] Step 3, annealing and straightening of finished products: the first rolled slab obtained in step 2 is annealed at 750° C. for 70 minutes, and is hot-straightened by a roller straightener after being taken out of the furnace until the roughness requirement of the finished product is met, and is air-cooled to room temperature to obtain a medium-thick slab of R60705 zirconium alloy; the medium-thick slab of R60705 zirconium alloy has a thickness of 20 mm and a width of 2400 mm;

[0037] Step 4: Finished product grinding, shearing and pickling: The R60705 zirconium alloy medium and thick plate blank obtained in step 3 is ground to remove the surface oxide scale, and is ground to the required thickness of the finished product, and then sheared to the required length and width of the finished product, and then pickled to obtain the finished R60705 zirconium alloy medium and thick plate; the R60705 zirconium alloy medium and thick plate has a thickness of 20 mm, a width of 2360 mm, and a length of 3500 mm.

[0038] Figure 1 The metallographic structure diagram (200×) of the R60705 zirconium alloy medium and thick plate prepared in this embodiment is shown in FIG. Figure 1 It can be seen that the overall metallographic structure of the R60705 zirconium alloy medium and thick plate is a uniform and fine two-phase structure.

[0039] According to tests, the room temperature tensile strength of the R60705 zirconium alloy medium and thick plate prepared in this embodiment is 650MPa-670MPa, the yield strength is 520MPa-640MPa, and the elongation after fracture is 28%-30%, which meets the requirements of ASME SB-551 / ASMESB-551M standards.

[0040] In summary, the R60705 zirconium alloy medium and thick plate prepared in this embodiment has a uniform and fine microstructure and excellent mechanical properties.

[0041] Example 2

[0042] This embodiment includes the following steps:

[0043] Step 1, blank making: the R60705 zirconium alloy ingot is subjected to four-fire forging, wherein the heating temperature of the first fire forging and the second fire forging is 1000°C, the initial forging temperature is 926°C, and the final forging temperature is 742°C, the heating temperature of the third fire forging and the fourth fire forging is 950°C, the initial forging temperature is 865°C, and the final forging temperature is 723°C, and the cooling method after each fire forging is air cooling, followed by grinding to remove the surface oxide scale, and ultrasonic flaw detection is performed after grinding of the fourth fire forging, and the result must meet the A1 level requirements of GB / T5193-2007 "Ultrasonic Flaw Detection Method for Titanium and Titanium Alloy Processing Products", and pass the appearance size and surface quality inspection to obtain the R60705 zirconium alloy forging slab; the R60705 zirconium alloy forging slab has a thickness of 160.3 mm, a width of 2395 mm, and a length of 802 mm;

[0044] Step 2, billet heating and billet rolling: the surface of the R60705 zirconium alloy forging slab obtained in step 1 is coated with an anti-oxidation coating, and then heated to 900°C for the first hot rolling, combined with online reheating, and the first rolled slab is obtained after cooling; the first hot rolling is unidirectional rolling, and the pass deformation rates are 7.5%, 8.8%, 9.6%, and 9.8% respectively. After reheating for 90 minutes, rolling is continued, and the pass deformation is The deformation rates are 12.7%, 14.6%, 15.9%, 15.2%, and 14.5% respectively. After returning to the furnace for 55 minutes, the rolling is continued. The deformation rates of each pass are 16.0%, 16.7%, 17.1%, 15.5%, and 14.3% respectively. The number of passes is 14, and the total deformation rate is 87.5%. After completion, the first rolled slab is air-cooled to room temperature. The thickness of the first rolled slab is 21 mm, the width is 2395 mm, and the length is 5500 mm.

[0045] Step 3, semi-finished product grinding and second-fire blanking: the first rolled slab obtained in step 2 is ground to remove the surface oxide scale, and then cut to obtain a first intermediate slab; the first intermediate slab has a thickness of 21 mm, a width of 2395 mm, and a length of 850 mm;

[0046] Step 4, second-fire heating and second-fire rolling: The first intermediate slab obtained in step 3 is heated to a temperature of 860°C and then rolled for a second time, and combined with online reheating to obtain a second rolled slab; the deformation rates of the second rolling passes are 19%, 17.6%, 17.9%, 17.4%, and 15.8%, respectively, the number of passes is 5, the total deformation rate is 62%, and the rolling direction of the second rolling is perpendicular to the rolling direction of the first rolling in step 2; the thickness of the second rolled slab is 8 mm, the width is 850 mm, and the length is 5900 mm;

[0047] Step 5, semi-finished product grinding and three-fire blanking: the second rolled slab obtained in step 4 is ground to remove the surface oxide scale, and then cut to obtain a second intermediate slab; the second intermediate slab has a thickness of 8 mm, a width of 850 mm, and a length of 1950 mm;

[0048] Step 6, three-fire heating and three-fire rolling: The second intermediate slab obtained in step 5 is heated to a temperature of 840°C and then rolled for the third time, and combined with online reheating to obtain a third rolled slab; the deformation rates of the third rolling are 18.8%, 16.9%, and 14.8% respectively, the number of passes is 3, the total deformation rate is 42.5%, and the rolling direction of the third rolling is perpendicular to the rolling direction of the second rolling in step 4; the thickness of the third rolled slab is 4.5 mm, the width is 850 mm, and the length is 3100 mm;

[0049] Step 7, annealing and straightening of finished products: the third rolled slab obtained in step 6 is annealed at 700° C. for 34 minutes, and is straightened by a roller straightener after being taken out of the furnace until the roughness requirement of the finished product is met, and is air-cooled to room temperature to obtain a R60705 zirconium alloy medium-thick slab; the R60705 zirconium alloy medium-thick slab has a thickness of 4.5 mm and a width of 850 mm;

[0050] Step 8. Finished product grinding, shearing and pickling: The R60705 zirconium alloy medium and thick plate blank obtained in step 7 is ground to remove the surface oxide scale, and is ground to the required thickness of the finished product, and then sheared to the required length and width of the finished product, and then pickled to obtain the finished R60705 zirconium alloy medium and thick plate; the R60705 zirconium alloy medium and thick plate has a thickness of 4.5 mm, a width of 800 mm, and a length of 3000 mm.

[0051] Figure 2 The metallographic structure diagram (200×) of the R60705 zirconium alloy medium and thick plate prepared in this embodiment is shown in FIG. Figure 2 It can be seen that the overall metallographic structure of the R60705 zirconium alloy medium and thick plate is a uniform and fine two-phase structure.

[0052] After testing, the room temperature tensile strength of the R60705 zirconium alloy medium and thick plate prepared in this embodiment is 576MPa-610MPa, the yield strength is 460MPa-532MPa, and the elongation after fracture is 29%-32%, which meets the requirements of ASME SB-551 / ASMESB-551M standards, and the bending meets 3T, 105°.

[0053] In summary, the R60705 zirconium alloy medium and thick plate prepared in this embodiment has a uniform and fine microstructure and excellent mechanical properties.

[0054] Example 3

[0055] This embodiment includes the following steps:

[0056] Step 1, blank making: the R60705 zirconium alloy ingot is subjected to four-fire forging, wherein the heating temperature of the first fire forging and the second fire forging is 1030°C, the initial forging temperature is 968°C, and the final forging temperature is 752°C, the heating temperature of the third fire forging and the fourth fire forging is 980°C, the initial forging temperature is 901°C, and the final forging temperature is 738°C, and the cooling method after each fire forging is air cooling, followed by grinding to remove the surface oxide scale, and ultrasonic flaw detection is performed after grinding of the fourth fire forging, and the result must meet the A1 level requirements of GB / T5193-2007 "Ultrasonic Flaw Detection Method for Titanium and Titanium Alloy Processing Products", and pass the appearance size and surface quality inspection to obtain the R60705 zirconium alloy forging slab; the R60705 zirconium alloy forging slab has a thickness of 239.5 mm, a width of 800 mm, and a length of 1400 mm;

[0057] Step 2, blank heating and blank rolling: the surface of the R60705 zirconium alloy forging slab obtained in step 1 is coated with an anti-oxidation coating, and then heated to a temperature of 920°C for the first hot rolling, combined with online reheating and heating, and the first rolled slab is obtained after cooling; the first hot rolling is unidirectional rolling, and the pass deformation rates are 9.2%, 10.6%, 11.8%, and 12.8% respectively. After reheating for 130 minutes, warm rolling is continued, and the pass deformation rates are 14.0%, 15.5%, 14.7%, and 14.0% respectively. The number of passes is 8, and the total deformation rate is 66.6%. After completion, it is air-cooled to room temperature; the thickness of the first rolled slab is 80 mm, the width is 800 mm, and the length is 3500 mm;

[0058] Step 3, annealing and straightening of finished products: the first rolled slab obtained in step 2 is annealed at 800° C. for 140 min, and is straightened by a roller straightener after being taken out of the furnace until the roughness requirement of the finished product is met, and is air-cooled to room temperature to obtain a R60705 zirconium alloy medium-thick slab; the R60705 zirconium alloy medium-thick slab has a thickness of 80 mm and a width of 800 mm;

[0059] Step 4: Finished product grinding, shearing and pickling: The R60705 zirconium alloy medium and thick plate blank obtained in step 3 is ground to remove the surface oxide scale, and is ground to the required thickness of the finished product, and then sheared to the required length and width of the finished product, and then pickled to obtain the finished R60705 zirconium alloy medium and thick plate; the R60705 zirconium alloy medium and thick plate has a thickness of 80 mm, a width of 600 mm, and a length of 3000 mm.

[0060] Figure 3The metallographic structure diagram (200×) of the R60705 zirconium alloy medium and thick plate prepared in this embodiment is shown in FIG. Figure 3 It can be seen that the overall metallographic structure of the R60705 zirconium alloy medium and thick plate is a uniform and fine two-phase structure.

[0061] After testing, the room temperature tensile strength of the R60705 zirconium alloy medium and thick plate prepared in this embodiment is 640MPa-665MPa, the yield strength is 570MPa-630MPa, and the elongation after fracture is 26%-31%, which meets the requirements of ASME SB-551 / ASMESB-551M standard, and the bending meets 3T, 105°,

[0062] In summary, the R60705 zirconium alloy medium and thick plate prepared in this embodiment has a uniform and fine microstructure and excellent mechanical properties.

[0063] Example 4

[0064] This embodiment includes the following steps:

[0065] Step 1, blank making: subjecting the R60705 zirconium alloy ingot to four-fire forging, wherein the heating temperature of the first and second fire forgings is 1020°C, the initial forging temperature is 962°C, and the final forging temperature is 755°C, the heating temperature of the third and fourth fire forgings is 970°C, the initial forging temperature is 883°C, and the final forging temperature is 762°C, and the cooling method after each fire forging is air cooling, followed by grinding to remove the surface oxide scale, and ultrasonic flaw detection is performed after grinding of the fourth fire forging, and the result must meet the A1 level requirements of GB / T5193-2007 "Ultrasonic Flaw Detection Method for Titanium and Titanium Alloy Processing Products", and pass the appearance size and surface quality inspection to obtain the R60705 zirconium alloy forging slab; the R60705 zirconium alloy forging slab has a thickness of 215 mm, a width of 1250 mm, and a length of 1050 mm;

[0066] Step 2, blank heating and blank rolling: the surface of the R60705 zirconium alloy forging slab obtained in step 1 is coated with an anti-oxidation coating, and then heated to a temperature of 920°C for the first hot rolling, combined with online reheating and heating, and the first rolled slab is obtained after cooling; the first hot rolling is unidirectional rolling, and the pass deformation rates are 7.9%, 9.1%, 11.1%, 12.5%, 14.3%, 15.0%, 12.7%, and 12.4% respectively, the number of passes is 8, the total deformation rate is 63.7%, and after completion, it is air-cooled to room temperature; the thickness of the first rolled slab is 78 mm, the width is 1250 mm, and the length is 2450 mm;

[0067] Step 3, semi-finished product grinding and second-fire blanking: the first rolled slab obtained in step 2 is ground to remove the surface oxide scale, and then cut to obtain a first intermediate slab; the first intermediate slab has a thickness of 78 mm, a width of 1250 mm, and a length of 2380 mm;

[0068] Step 4, second-fire heating and second-fire rolling: The first intermediate slab obtained in step 3 is heated to a temperature of 880°C and then rolled for a second time, and combined with online reheating to obtain a second rolled slab; the deformation rates of the second rolling are 16.7%, 15.4%, 14.5%, and 14.9% respectively, the number of passes is 4, the total deformation rate is 48.7%, and the rolling direction of the second rolling is perpendicular to the rolling direction of the first rolling in step 2; the thickness of the second rolled slab is 40 mm, the width is 2380 mm, and the length is 2450 mm;

[0069] Step 5, semi-finished product grinding and three-fire blanking: the second rolled slab obtained in step 4 is ground to remove the surface oxide scale, and then cut to obtain a second intermediate slab; the second intermediate slab has a thickness of 40 mm, a width of 2380 mm, and a length of 2400 mm;

[0070] Step 6, three-fire heating and three-fire rolling: The second intermediate slab obtained in step 5 is heated to a temperature of 860°C and then rolled for the third time, and combined with online reheating to obtain a third rolled slab; the deformation rates of the third rolling are 15.5%, 14.8%, 13.9%, 13.3%, and 11.6% respectively, the number of passes is 5, the total deformation rate is 52.5%, and the rolling direction of the third rolling is perpendicular to the rolling direction of the second rolling in step 4; the thickness of the third rolled slab is 19 mm, the width is 2400 mm, and the length is 4900 mm;

[0071] Step 7, annealing and straightening of finished products: the third rolled slab obtained in step 6 is annealed at 750° C. for 60 min, and is hot-straightened by a roller straightener after being taken out of the furnace until the roughness requirement of the finished product is met, and is air-cooled to room temperature to obtain a R60705 zirconium alloy medium-thick slab; the R60705 zirconium alloy medium-thick slab has a thickness of 19 mm and a width of 2400 mm;

[0072] Step 8. Finished product grinding, shearing and pickling: The R60705 zirconium alloy medium and thick plate blank obtained in step 7 is ground to remove the surface oxide scale, and is ground to the required thickness of the finished product, and then sheared to the required length and width of the finished product, and then pickled to obtain the finished R60705 zirconium alloy medium and thick plate; the R60705 zirconium alloy medium and thick plate has a thickness of 19 mm, a width of 2360 mm, and a length of 3000 mm.

[0073] Figure 4 The metallographic structure diagram (200×) of the R60705 zirconium alloy medium and thick plate prepared in this embodiment is shown in FIG. Figure 4 It can be seen that the overall metallographic structure of the R60705 zirconium alloy medium and thick plate is a uniform and fine two-phase structure.

[0074] After testing, the room temperature tensile strength of the R60705 zirconium alloy medium and thick plate prepared in this embodiment is 610MPa-640MPa, the yield strength is 490MPa-580MPa, and the elongation after fracture is 26%-30%, which meets the requirements of ASME SB-551 / ASMESB-551M standards, and the bending meets 3T, 105°.

[0075] In summary, the R60705 zirconium alloy medium and thick plate prepared in this embodiment has a uniform and fine microstructure and excellent mechanical properties.

[0076] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for rolling R60705 zirconium alloy medium and thick plates, characterized in that: The method comprises the following steps: Step 1, blank making: the R60705 zirconium alloy ingot is subjected to four-fire forging, and the cooling method after each fire forging is air cooling, and then the surface oxide scale is removed by grinding, and ultrasonic flaw detection is performed after the grinding of the fourth fire forging, and the result must meet the A1 level requirements of GB / T5193-2007 "Ultrasonic flaw detection method for titanium and titanium alloy processed products", and pass the appearance size and surface quality inspection to obtain the R60705 zirconium alloy forging blank; the R60705 zirconium alloy forging blank has a thickness of 160mm to 240mm, a width of 800mm to 2400mm, and a length of more than 800mm; Step 2, blank heating and blank rolling: coating the surface of the R60705 zirconium alloy forged slab obtained in step 1 with an anti-oxidation coating, then heating and performing the first fire rolling, and obtaining the first rolled slab after cooling; the first fire rolling has a pass deformation rate of 4% to 23%, and the number of passes is 8 to 14; the first rolled slab has a thickness of 20 mm to 80 mm, and a width of 800 mm to 2400 mm; Step 3, semi-finished product grinding and second-fire blanking: the first rolled slab obtained in step 2 is ground to remove the surface oxide scale, and then cut to obtain a plurality of first intermediate slabs; the first intermediate slabs have a thickness of 20 mm to 80 mm and a length of 800 mm to 2400 mm; Step 4, second-fire heating and second-fire rolling: The first intermediate slab obtained in step 3 is heated and rolled for the second time, and combined with online reheating to obtain a second rolled slab; the deformation rate of the second rolling is 10% to 25%, the number of passes is 3 to 6, and the rolling direction of the second rolling is perpendicular to the rolling direction of the first rolling in step 2; the thickness of the second rolled slab is 8 mm to 40 mm, and the width is 800 mm to 2400 mm; Step 5, semi-finished product grinding and three-fire blanking: the second rolled slab obtained in step 4 is ground to remove the surface oxide scale, and then cut to obtain a plurality of second intermediate slabs; the thickness of the second intermediate slab is 8 mm to 40 mm, and the length or width is 800 mm to 2400 mm; Step 6, three-fire heating and three-fire rolling: The second intermediate slab obtained in step 5 is heated and rolled for the third time to obtain a third rolled slab; the pass deformation rate of the third rolling is 10% to 25%, the number of passes is 3 to 6, and the rolling direction of the third rolling is parallel or perpendicular to the rolling direction of the second rolling in step 4; the thickness of the third rolled slab is 4 mm to 20 mm, and the width is 800 mm to 2400 mm; Step 7, annealing and straightening of finished products: annealing and straightening the first rolled slab obtained in step 2, the second rolled slab obtained in step 4, or the third rolled slab obtained in step 6, and cooling to obtain R60705 zirconium alloy medium-thick slab; the R60705 zirconium alloy medium-thick slab has a thickness of 4 mm to 80 mm and a width of 800 mm to 2400 mm; Step 8: Finished product grinding, shearing and pickling: The R60705 zirconium alloy medium and thick plate blank obtained in step 7 is ground to remove the surface oxide scale, and is ground to the required thickness of the finished product, and then sheared to the required length and width of the finished product, and then pickled to obtain the finished R60705 zirconium alloy medium and thick plate; the finished R60705 zirconium alloy medium and thick plate has a thickness of 4 mm to 80 mm and a width of less than 2400 mm.

2. The method for rolling a R60705 zirconium alloy medium and thick plate according to claim 1, characterized in that: During the four-fire forging process described in step one, the heating temperature of the first fire forging and the second fire forging is 1000°C to 1050°C, the initial forging temperature is above 900°C, and the final forging temperature is above 700°C. The heating temperature of the third fire forging and the fourth fire forging is 950°C to 1000°C, the initial forging temperature is above 850°C, and the final forging temperature is above 700°C.

3. The method for rolling a R60705 zirconium alloy medium and thick plate according to claim 1, characterized in that: The specific process of the first rolling in step 2 is: it is carried out at a temperature of 900°C to 940°C, and combined with online reheating and heating, the total deformation rate of the first rolling is 60% to 90%; the first rolling is widening rolling or unidirectional rolling, and the thickness of the finished R60705 zirconium alloy medium and thick plate directly prepared by the first rolling is 20mm to 80mm, wherein, when the thickness of the finished R60705 zirconium alloy medium and thick plate is 20mm to 40mm and the finished product is obtained by one rolling, widening rolling is selected: first, the heated R60705 zirconium alloy forging slab is rolled to 1.2 to 1.4 times of the original length, and then rotated 90°, combined with online reheating and heating rolling to the target thickness, when the size of the widened rolled slab exceeds the processing range of the rolling mill or a plurality of plates of different thicknesses are obtained by rolling a forged slab, multiple rolling is selected to obtain the finished product.

4. The method for rolling a R60705 zirconium alloy medium and thick plate according to claim 1, characterized in that: The specific process of the second rolling in step 4 is: carried out at a temperature of 860°C to 880°C, combined with online reheating, and the total deformation rate of the second rolling is 45% to 65%.

5. The method for rolling a R60705 zirconium alloy medium and thick plate according to claim 1, characterized in that: The specific process of the third rolling in step six is: the third rolling is carried out at a temperature of 840° C. to 860° C., and the total deformation rate of the third rolling is 40% to 55%.

6. The method for rolling a R60705 zirconium alloy medium and thick plate according to claim 1, characterized in that: The specific process of the annealing treatment in step seven is: keeping warm at a temperature of 700°C to 800°C for (H+30 to H+60) min, H is the thickness of the annealed slab in mm, and after being taken out of the furnace, it is hot straightened by a roller straightener to meet the unevenness requirements of the finished product; the cooling is wind cooling or air cooling, wherein when the thickness of the finished R60705 zirconium alloy medium and thick plate is greater than 20 mm, wind cooling to room temperature is selected, and when the thickness of the finished R60705 zirconium alloy medium and thick plate does not exceed 20 mm, air cooling to room temperature is selected.

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