Vanadium grain refining method

Abstract

The invention relates to the technical field of metal target metallography, and discloses a vanadium grain refinement method which comprises the following steps: step 1, heating and forging a vanadium cast ingot to obtain a vanadium block; 2, the vanadium block is subjected to subzero treatment and rolled, and a vanadium sheet is obtained; and 3, the vanadium sheet is subjected to vacuum annealing treatment, and the annealing temperature ranges from 900 DEG C to 1000 DEG C. By means of the method, the grain size of vanadium can be refined to be smaller than 20 microns.

Description

Technical Field

[0001] The invention relates to the technical field of metallographic phase of metal targets, and in particular to a vanadium grain refinement method. Background Art

[0002] The grain size of the vanadium target blank has a crucial influence on the sputtering performance. The existing technology mainly uses a combination of hot forging, hot rolling and heat treatment to refine the grain size of the vanadium target blank. First, the vanadium ingot is heated to a certain temperature for forging and rolling to cause plastic deformation. Then, through a heat treatment process, the deformed and refined grains are recrystallized at high temperature to further refine the grain size. Although the existing technology can achieve the preparation of vanadium targets, there are still some problems and limitations. First, the grain size of the vanadium target blank prepared by the existing combination of hot forging, hot rolling and heat treatment is not small and uniform enough. Secondly, vanadium is very easy to adsorb impurity elements such as O, N, and H in a high temperature environment, which reduces the plasticity of vanadium, and the produced vanadium oxide is easy to melt at high temperature, has certain toxicity, and is not conducive to safety and environmental protection.

[0003] CN202011580420 discloses a method for preparing a high-purity vanadium target blank and a high-purity vanadium target material obtained using the same, the preparation method comprising: forging, annealing, rolling and re-annealing a vanadium ingot in sequence to obtain a high-purity vanadium target blank; wherein the re-annealing temperature is 450-550°C. The rolling controls the pressing amount of each pass to be 0.5-1mm; preferably, the total deformation of the rolling is 70-80%. The holding time of the re-annealing is 90-150min; preferably, water cooling is performed after the re-annealing to obtain the high-purity vanadium target blank. This method can refine the grains of the vanadium target material by forging, annealing, rolling and re-annealing, and controlling the re-annealing temperature to 450-550°C, with the grain size being ≤50 microns. However, the grain refinement degree is poor through this method, and during the rolling process, the surface of the vanadium target material is easily oxidized to produce vanadium oxides, which are toxic and affect the health of workers.

[0004] Therefore, the technical problem to be solved by the present invention is: how to improve the grain refinement degree of vanadium and reduce the oxidation degree of vanadium during the preparation process. Summary of the invention

[0005] The main purpose of the present invention is to provide a vanadium grain refinement method, which is to perform deep cold rolling on the vanadium ingot and then heat it to 900-1000°C for annealing, so that the grains of vanadium during recrystallization are further refined.

[0006] To achieve the above objectives, the technical solutions adopted in this application are:

[0007] A vanadium grain refinement method comprises the following steps:

[0008] Step 1: heating and forging the vanadium ingot to obtain a vanadium block;

[0009] Step 2: Cryogenically treat the vanadium block and roll it to obtain a vanadium sheet;

[0010] Step 3: Perform vacuum annealing on the vanadium sheet at a temperature of 900-1000°C.

[0011] In some embodiments of the present invention, the annealing temperature is preferably 900°C, 920°C, 940°C, 960°C, 980°C, or 1000°C.

[0012] This scheme adopts deep cold rolling and vacuum annealing. Through deep cold rolling of vanadium, vanadium can accumulate more deformation energy storage under the condition of small deformation, thus providing stronger driving force for vanadium recrystallization. Then annealing of vanadium at 900-1000℃ makes vanadium grains recrystallize in this temperature range, thus achieving vanadium grain refinement, and the obtained vanadium grain size is less than 20 microns. When the temperature is less than this range, the vanadium grain recrystallization effect is not good, and when the temperature is greater than this range, the vanadium grains will grow excessively, making the size of the vanadium grains larger.

[0013] Preferably, the step 2 specifically comprises: placing the vanadium block in liquid nitrogen to reduce the temperature of the vanadium block to -150 to -80°C, and rolling the block; after the rolling is completed, the block is naturally heated to room temperature.

[0014] In some embodiments of the present invention, the vanadium ingot is placed in liquid nitrogen to reduce the temperature of the vanadium ingot to preferably -150°C, -140°C, -130°C, -120°C, -110°C, -100°C, -90°C, or -80°C.

[0015] Preferably, during the rolling process, the deformation rate of a single rolling does not exceed 2%, and the total rolling deformation rate is 30-50%.

[0016] In some embodiments of the present invention, the deformation rate of a single rolling is preferably 0.5%, 1%, 1.5%, or 2%; the total rolling deformation rate is preferably 30%, 35%, 40%, 45%, or 50%.

[0017] Preferably, in step 3, during the vacuum annealing process, the vacuum degree is 10 -2 ~10 -1 Pa; annealing time is 30 to 90 minutes.

[0018] In some embodiments of the present invention, the vacuum degree is preferably 0.01Pa, 0.05Pa, or 0.1Pa; and the annealing time is preferably 30min, 40min, 50min, 60min, 70min, 80min, or 90min.

[0019] Preferably, the step 1 comprises the following steps:

[0020] Step A: heating the vanadium ingot;

[0021] Step B: After the heating is completed, the vanadium ingot is forged for multiple times, and after each forging is completed, the vanadium ingot is heated again;

[0022] Step C: After the multiple forging passes are completed, the vanadium ingot is annealed.

[0023] Preferably, in step A, the heating temperature is 500-600° C. and the heating time is 30-60 min.

[0024] In some embodiments of the present invention, the heating temperature is preferably 500°C, 520°C, 540°C, 560°C, 580°C, or 600°C; and the heating time is preferably 30 min, 40 min, 50 min, or 60 min.

[0025] Preferably, in step B, the number of forging is 2 to 4 times; the deformation rate of each forging is 20 to 40%, and the total deformation rate of forging is 60 to 80%; the reheating temperature is 500 to 600° C.; and the reheating time is 20 to 30 minutes.

[0026] In some embodiments of the present invention, the number of forging is preferably 2, 3, or 4 times; the deformation rate of each forging is preferably 20%, 25%, 30%, 35%, or 40%; the total deformation rate of forging is preferably 60%, 65%, 70%, 75%, or 80%; the reheating temperature is preferably 500°C, 520°C, 540°C, 560°C, 580°C, or 600°C; and the reheating time is preferably 20 min, 22 min, 24 min, 26 min, 28 min, or 30 min.

[0027] Preferably, in step C, the heating temperature is 500-600° C. and the heating time is 30-120 min.

[0028] In some embodiments of the present invention, the heating temperature is preferably 500, 520, 540, 560, 580, or 600° C.; the heating time is preferably 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, or 120 min.

[0029] Preferably, the mass fraction of vanadium in the vanadium embryo is 99.9% to 99.99%, and the rest are inevitable impurities.

[0030] Compared with the prior art, this solution has the following beneficial effects:

[0031] The vanadium grain refining method of the present invention adopts deep cold rolling combined with vacuum annealing at 900-1000°C to refine vanadium grains, processes vanadium by deep cold rolling so that vanadium can obtain more deformation energy storage and dislocation density, and then heats to 900-1000°C for annealing to recrystallize the vanadium grains, and through the synergistic effect of deep cold rolling and annealing at 900-1000°C, the vanadium grain size is reduced to less than 20 microns.

[0032] Secondly, by treating vanadium through deep cold rolling, it can be prevented that vanadium absorbs elements such as O, N, and H in the air during the rolling process, thereby reducing the plasticity of vanadium. Secondly, since vanadium oxides are toxic to a certain extent, the production of vanadium oxides in the air can be avoided as much as possible, thereby improving production safety and better meeting environmental protection requirements. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the present application implemented as generally shown here can be arranged and designed in various different configurations.

[0034] Example 1

[0035] A vanadium grain refinement method comprises the following steps:

[0036] Step 1: Place the vanadium ingot into a box-type heating furnace for heating; the heating temperature is 550° C. and the heating time is 45 minutes; the mass fraction of vanadium in the vanadium ingot is 99.99%, and the rest is inevitable impurities.

[0037] Step 2: After heating is completed, the vanadium ingot is forged for the first time using an air hammer. The deformation rate of the first forging is 23%. After the first forging is completed, the vanadium ingot is placed in a furnace for reheating at a temperature of 550°C for 25 minutes. After the reheating is completed, the second forging is performed. The deformation rate of the second forging is 23%. After the second forging is completed, the vanadium ingot is placed in a furnace for reheating at a temperature of 550°C for 25 minutes. After completion, the third forging is performed. The total deformation rate of the forging is 70%.

[0038] Step 3: After multiple forging passes, the vanadium ingot is annealed; the annealing temperature is 550°C, the annealing time is 90 minutes, and then cooled by air cooling;

[0039] Step 4: Put the vanadium block into liquid nitrogen to reduce the temperature of the vanadium block to -120°C and then roll it. During the rolling process, the deformation rate of a single rolling is 2%, and the total deformation rate of rolling is 50%. After the rolling is completed, the temperature is naturally returned to room temperature.

[0040] Step 5: Vacuum anneal the vanadium sheet at a temperature of 950°C. During the vacuum annealing process, the vacuum degree is 10 -2 Pa; annealing time is 60min.

[0041] Example 2

[0042] This embodiment is basically the same as embodiment 1, except that: Step 5: vacuum annealing the vanadium sheet at a temperature of 900°C; during the vacuum annealing process, the vacuum degree is 10 -2 Pa; annealing time is 60min.

[0043] Example 3

[0044] This embodiment is basically the same as embodiment 1, except that: Step 5: vacuum annealing the vanadium sheet at a temperature of 1000°C; during the vacuum annealing process, the vacuum degree is 10 -2 Pa; annealing time is 60min.

[0045] Example 4

[0046] This embodiment is basically the same as the embodiment 1, except that: Step 1: placing the vanadium ingot into a box-type heating furnace for heating; the heating temperature is 500° C., and the heating time is 60 min; the mass fraction of vanadium in the vanadium ingot is 99.99%, and the rest is unavoidable impurities.

[0047] Step 2: After heating, the vanadium ingot is forged for the first time using an air hammer. The deformation rate of the first forging is 30%. After the first forging is completed, the vanadium ingot is placed in the furnace for reheating at a temperature of 500°C for 30 minutes. After the reheating is completed, the second forging is performed. The deformation rate of the second forging is 30%, and the total deformation rate of forging is 60%.

[0048] Step 3: After multiple forging passes, the vanadium ingot is annealed; the annealing temperature is 500°C, the annealing time is 120 minutes, and then cooled by air cooling;

[0049] Step 4: Put the vanadium block into liquid nitrogen to reduce the temperature of the vanadium block to -80°C and then roll it. During the rolling process, the deformation rate of a single rolling is 1%, and the total deformation rate of rolling is 30%. After the rolling is completed, the temperature is naturally returned to room temperature.

[0050] Step 5: Vacuum anneal the vanadium sheet at a temperature of 950°C. During the vacuum annealing process, the vacuum degree is 10 -2 Pa; annealing time is 120min.

[0051] Example 5

[0052] This embodiment is basically the same as the embodiment 1, except that: Step 1: placing the vanadium ingot into a box-type heating furnace for heating; the heating temperature is 600° C., and the heating time is 30 min; the mass fraction of vanadium in the vanadium ingot is 99.99%, and the rest is unavoidable impurities.

[0053] Step 2: After the heating is completed, the vanadium ingot is forged for the first time using an air hammer. The deformation rate of the first forging is 20%. After the first forging is completed, the vanadium ingot is placed in a furnace for reheating at a temperature of 500°C and a reheating time of 30 minutes. After the reheating is completed, the second forging is performed. The deformation rate of the second forging is 20%. After the second forging is completed, the vanadium ingot is placed in a furnace for reheating at a temperature of 500°C and a reheating time of 30 minutes. After the reheating is completed, the third forging is performed. The deformation rate of the third forging is 20%. After the third forging is completed, the vanadium ingot is placed in a furnace for reheating at a temperature of 500°C and a reheating time of 30 minutes. After the reheating is completed, the fourth forging is performed. The deformation rate of the fourth forging is 20%, and the total deformation rate of forging is 80%.

[0054] Step 3: After multiple forging passes, the vanadium ingot is annealed; the annealing temperature is 600°C, the annealing time is 30 minutes, and then cooled by air cooling;

[0055] Step 4: Put the vanadium block into liquid nitrogen to reduce the temperature of the vanadium block to -150°C and then roll it. During the rolling process, the deformation rate of a single rolling is 1.5%, and the total deformation rate of rolling is 40%. After the rolling is completed, the temperature is naturally returned to room temperature.

[0056] Step 5: Vacuum anneal the vanadium sheet at a temperature of 1000°C. During the vacuum annealing process, the vacuum degree is 10 -2 Pa; annealing time is 30min.

[0057] Comparative Example 1

[0058] This comparative example is basically the same as Example 1, except that: Step 4: The vanadium block is heated to 550°C and kept warm for 1 hour, then rolled for the first time, placed in a furnace and kept warm at 550°C for 20 minutes, and then rolled. After rolling, it is placed in a furnace and kept warm at 550°C for 20 minutes. The rolling amount per pass is 2%, and the total deformation is rolled to 20%.

[0059] Comparative Example 2

[0060] This comparative example is basically the same as Example 1, except that: Step 4: hot rolling the vanadium block, and controlling the pressing amount of each pass to 0.7 mm, and controlling the total deformation amount to 75%, until vanadium with a target diameter and a target thickness is obtained;

[0061] Step 5: The vanadium sheet is subjected to vacuum annealing treatment at a temperature of 500° C. and a holding time of 120 min.

[0062] Comparative Example 3

[0063] This comparative example is basically the same as Example 1, except that: Step 5: vacuum annealing the vanadium sheet at a temperature of 800°C; during the vacuum annealing process, the vacuum degree is 10 -2 Pa; annealing time is 30min.

[0064] Comparative Example 4

[0065] This comparative example is basically the same as Example 1, except that: Step 5: vacuum annealing the vanadium sheet at a temperature of 1200°C; during the vacuum annealing process, the vacuum degree is 10 -2 Pa; annealing time is 30min.

[0066] Vanadium was prepared by the methods of Examples 1 to 5 and Comparative Examples 1 to 4 respectively, and the surface state of the vanadium was measured by observing the surface color of the vanadium with naked eyes; and the grain size of the vanadium was measured by a metallographic microscope.

[0067] The results are shown in Table 1:

[0068] Table 1 Test results of vanadium

[0069] Group Surface state Grain size (μm) Example 1 No cracks, dark grey 15.6 Example 2 No cracks, dark grey 12.8 Example 3 No cracks, dark grey 18.5 Example 4 No cracks, gray 18.6 Example 5 No cracks, dark grey 19.4 Comparative Example 1 No cracks, orange-yellow 88.5 Comparative Example 2 Cracked, dark gray 31.8 Comparative Example 3 No cracks, dark grey Partial crystallization Comparative Example 4 No cracks, gray 43.3

[0070] Result analysis:

[0071] It can be seen from Examples 1 to 5 that at an annealing temperature of 900°C to 1000°C, combined with deep cold rolling, vanadium with a grain size of less than 20 μm can be obtained, and within the range of 900°C to 1000°C, the lower the temperature, the smaller the vanadium grain size. Secondly, as long as the other parameters are within the corresponding range, vanadium with a grain size of less than 20 μm can be obtained.

[0072] It can be seen from Example 1 and Comparative Example 1 that the vanadium grain size is 88.5μm by hot rolling and 950℃ vacuum annealing, while the vanadium grain size is 15.6μm by deep cold rolling and 900℃~1000℃ vacuum annealing. The grain size of Example 1 is significantly smaller than that of Comparative Example 1. The reason is that: by hot rolling, the cumulative deformation energy storage of vanadium is small, and after annealing, the deformation energy storage is released. Due to the small deformation energy storage, the purpose of grain refinement cannot be achieved. By deep cold rolling, the vanadium can obtain more deformation energy storage at a smaller deformation, thereby achieving the purpose of grain refinement. Secondly, by hot rolling, a layer of orange-yellow oxide will be produced on the surface of vanadium, and it needs to be ground or polished in the subsequent process, which reduces production efficiency.

[0073] It can be seen from Example 1 and Comparative Examples 2 to 4 that the vanadium grain size is 31.8 μm by using the process of hot rolling and 500°C annealing. The vanadium grain size will be refined to a certain extent, but the grain refinement degree of Example 1 is relatively weak. The reason is that although the deformation energy storage obtained by hot rolling is small, the temperature is low in the case of 500°C annealing, and the size of the recrystallized grains is small. Grain refinement is achieved through the combined action of hot rolling and 500°C annealing. According to Comparative Example 3, when the method is annealed at 800°C, the crystallinity is small, some grains are very small, and some have no obvious grain boundaries. When the temperature exceeds 1000 degrees Celsius, the vanadium grains grow abnormally and cannot meet the use requirements. It can be seen that through the process of deep cold rolling and vacuum annealing at 900°C to 1000°C, the vanadium grain size can be refined to less than 20 μm.

[0074] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for refining vanadium grains, characterized in that: The following steps are involved: Step 1: heating and forging the vanadium ingot to obtain a vanadium block; Step 2: Cryogenically treat the vanadium block and roll it to obtain a vanadium sheet; Step 3: Perform vacuum annealing on the vanadium sheet at a temperature of 900-1000°C.

2. The vanadium grain refinement method according to claim 1, characterized in that: The step 2 specifically includes: placing the vanadium block in liquid nitrogen to reduce the temperature of the vanadium block to -150 to -80°C, and rolling the block; after the rolling is completed, the block is naturally heated to room temperature.

3. The vanadium grain refinement method according to claim 2, characterized in that: During the rolling process, the deformation rate of a single rolling does not exceed 2%, and the total rolling deformation rate is 30-50%.

4. The vanadium grain refinement method according to claim 1, characterized in that: In the step 3, during the vacuum annealing process, the vacuum degree is 10 -2 ~10 -1 Pa; annealing time is 30 to 90 minutes.

5. The vanadium grain refinement method according to claim 1, characterized in that: The step 1 comprises the following steps: Step A: heating the vanadium ingot; Step B: After the heating is completed, the vanadium ingot is forged for multiple times, and after each forging is completed, the vanadium ingot is heated again; Step C: After the multiple forging passes are completed, the vanadium ingot is annealed.

6. The vanadium grain refinement method according to claim 5, characterized in that: In the step A, the heating temperature is 500-600° C. and the heating time is 30-60 min.

7. The vanadium grain refinement method according to claim 5, characterized in that: In the step B, the number of forging is 2 to 4 times; the deformation rate of each forging is 20 to 40%, and the total deformation rate of forging is 60 to 80%; the reheating temperature is 500 to 600° C.; and the reheating time is 20 to 30 minutes.

8. The vanadium grain refinement method according to claim 5, characterized in that: In the step C, the heating temperature is 500-600° C. and the heating time is 30-120 min.

9. The vanadium grain refinement method according to claim 1, characterized in that: The mass fraction of vanadium in the vanadium ingot is 99.9% to 99.99%, and the rest is inevitable impurities.