A forging method for controlling grain size uniformity of 0Cr16Ni15Mo2V stainless steel

Abstract

The present application relates to a kind of control 0Cr16Ni15Mo2V stainless steel grain size uniformity forging method, using free forging+precision forging combined method to produce fine crystal, homogenization 0Cr16Ni15Mo2V stainless steel, using the free forging of three upsetting six drawing mode, using low temperature multi-pass precision forging to control total deformation, and the method of rapid water cooling after forging, by the connection between the temperature, deformation of different upsetting, elongation of free forging and the deformation, hammer head frequency of different pass, feed speed of precision forging, the grain size of its forgings is controlled to be above 5 level and the cross section intensity difference is controlled to be within 2 level.

Description

Technical Field

[0001] This invention belongs to the field of stainless steel forging technology, specifically relating to a forging method for controlling the uniformity of grain size in 0Cr16Ni15Mo2V stainless steel. Background Technology

[0002] 0Cr16Ni15Mo2V stainless steel is primarily used as the main material for cladding tubes, outer sleeves, wires, and bars in nuclear fuel assemblies. Fuel element cladding temperatures can reach up to 650℃, and the deep depth of the fuel and the large number of fast neutrons necessitate extremely high high-temperature creep resistance and radiation resistance in the stainless steel. Coarse grains significantly reduce the material's high-temperature strength and corrosion resistance; therefore, the design requires a grain size ≥5. This type of steel cannot achieve grain refinement through heat treatment, making it very difficult to obtain uniform fine-grained steel. Furthermore, this steel contains elements such as Cr, Ni, and Ti; improper forging temperature and cooling control can lead to the formation of corresponding precipitates. Therefore, simultaneously considering precipitates and achieving grain refinement and homogenization presents a significant challenge. Summary of the Invention

[0003] This invention provides a forging method for controlling the uniformity of grain size in 0Cr16Ni15Mo2V stainless steel, which uses a combination of free forging and precision forging to produce fine-grained and uniform 0Cr16Ni15Mo2V stainless steel.

[0004] To address the above technical problems, this invention provides a forging method for controlling the uniformity of grain size in 0Cr16Ni15Mo2V stainless steel. The method is characterized by: rapid water cooling after free forging and precision forging of the steel ingot; the free forging employs a three-upsetting and six-drawing process, and the precision forging uses low-temperature multi-pass control of the total deformation; the specific steps of the three-upsetting and six-drawing process are as follows:

[0005] The temperature of the first upsetting is 1200±10℃, and the upsetting ratio is 1.80~1.85; then, after reheating in the furnace, the first and second upsetting are carried out, with the preheating temperature for drawing being 1200±10℃, and the forging ratios being controlled at 1.60~1.63 and 1.20~1.23 respectively.

[0006] The second upsetting temperature is 1190±10℃, and the upsetting ratio is 1.80~1.85. After reheating in the furnace, the third and fourth drawing are carried out. The drawing preheating temperature is 1190±10℃, and the forging ratio is controlled at 1.60~1.63 and 1.20~1.23 respectively.

[0007] The third upsetting temperature is 180±10℃, and the upsetting ratio is 1.85~1.90. After reheating in the furnace, the fifth and sixth drawing are carried out. The drawing preheating temperature is 1180±10℃, and the forging ratio is controlled at 1.65~1.70 and 1.25~1.30 respectively.

[0008] Furthermore, the steel ingot is preheated before precision forging. The ingot loading temperature is ≤650℃, and then the temperature is increased to 800~850℃ at ≤100℃ / h and held. Then the temperature is increased to 1120±10℃ at ≤100℃ / h and held. Then, six passes of drawing are performed.

[0009] Furthermore, during precision forging: the reduction amounts for the first to sixth passes are 40–45 mm, 70–80 mm, 40–45 mm, 70–80 mm, 70–80 mm, and 3–8 mm, respectively; the hammer impact frequency for the first to fifth passes is 170–180 times / min, and the hammer impact frequency for the sixth pass is 220–240 times / min; the feed rates for the first to sixth passes are 3.5–3.8 m / min, 3.8–4.0 m / min, 3.5–3.8 m / min, 3.8–4.0 m / min, 3.5–3.8 m / min, and 3.8–4.0 m / min, respectively.

[0010] Furthermore, the rotation angle for the first to sixth passes is 16.1° per stroke.

[0011] Furthermore, the overall forging ratio of precision forging is controlled at 2.60 to 2.65, and the final forging temperature is ≥950℃.

[0012] Furthermore, the forging is immediately immersed in water for cooling after free forging, with a water immersion time of ≤3 minutes, a water immersion temperature of ≥850℃, water cooling for ≥120 minutes, and water cooling to room temperature.

[0013] Furthermore, the forging is immediately immersed in water for cooling after precision forging, with the immersion time ≤3 minutes, the immersion temperature of the forging in water ≥850℃, water cooling for 25~30 minutes, and water cooling to room temperature.

[0014] Furthermore, before free forging, the preheated steel ingot is pre-deformed and elongated, with the forging ratio controlled at 1.05 to 1.10. During preheating, the furnace temperature for charging the steel ingot is below 500°C, and it should be kept at that temperature for more than 3 hours after entering the furnace. When the steel ingot is further heated to 800 to 850°C, it is preheated again at a rate of <100°C / h and a preheating time of more than 3.0 hours. After preheating, the steel ingot is further heated to the initial forging temperature of 1190±10°C at a rate of <100°C / h and a holding time of more than 5.0 hours.

[0015] Furthermore, the chemical composition of 0Cr16Ni15Mo2V stainless steel is controlled as follows: C: 0.040~0.080%, Si: 0.30~0.90%, S≤0.010%, P≤0.030%, Mn: 1.30~2.00%, Ni: 14.00~15.50%, Cr: 15.50~17.00%, Mo: 1.90~2.50%, Ti: 0.20~0.60%, V: 0.10~0.30%, and total oxygen: ≤0.0010%.

[0016] Furthermore, the jaws of the manipulator, as well as the hammer, anvil, and platform that come into contact with the forging, need to be preheated before forging, with a preheating temperature ≥200℃; the grain size of the forging should be controlled at level 5 or above and the cross-sectional strength difference should be controlled within level 2.

[0017] Beneficial effects: The innovation of this invention lies in the ability to manufacture fine-grained, homogeneous 0Cr16Ni15Mo2V stainless steel using a combined free forging and precision forging method. By controlling the temperature and deformation during free forging and combining it with low-temperature, multi-pass uniform deformation during precision forging, grain size homogenization is achieved, solving the current technical challenge of achieving grain size homogenization in 0Cr16Ni15Mo2V stainless steel.

[0018] This invention employs a three-upsetting and six-drawing method for free forging, combined with low-temperature multi-pass control of total deformation and rapid water cooling after forging in precision forging. The key point is the relationship between the temperature and deformation of different upsetting and drawing stages in free forging, the deformation of different passes in precision forging, the frequency of hammer pressing, and the feed speed, so that the grain size of the forging is controlled above level 5 and the cross-sectional strength difference is controlled within level 2.

[0019] This technology has promoted further improvement in the level of forged stainless steel technology, and increased the added value and market competitiveness of products. Attached Figure Description

[0020] Figure 1 This is a graph showing the relationship between holding temperature and holding time for different passes in the free forging process of steel ingots.

[0021] Figure 2 A graph showing the relationship between heating and holding time in precision forging of forgings.

[0022] Figure 3 (a)(b)(c) are schematic diagrams of grain size sampling of steel ingots at the edge, 1 / 2R and center after forging, respectively; Detailed Implementation

[0023] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below.

[0024] The present invention proposes a forging method for controlling the grain size uniformity of 0Cr16Ni15Mo2V stainless steel, the specific steps of which are as follows:

[0025] Step 1: The chemical composition of the 0Cr16Ni15Mo2V stainless steel of this invention is controlled as follows: C: 0.040~0.080%, Si: 0.30~0.90%, S≤0.010%, P≤0.030%, Mn: 1.30~2.00%, Ni: 14.00~15.50%, Cr: 15.50~17.00%, Mo: 1.90~2.50%, Ti: 0.20~0.60%, V: 0.10~0.30%, total oxygen: ≤0.0010%;

[0026] Step 2: The steel ingot is smelted using vacuum induction melting and vacuum self-consumption.

[0027] Step 3: Place alloys such as metallic manganese, metallic chromium, metallic nickel, molybdenum bars, and low-carbon ferrosilicon into a vacuum induction melting furnace. The refining vacuum degree is ≤5Pa, the refining time is ≥50min, and the tapping temperature is controlled at 1520~1600℃.

[0028] Step 4: Before vacuum consumable electrode melting, the surface of the consumable electrode billet produced in the vacuum induction melting furnace must be ground until it is shiny. The melting rate of the vacuum consumable electrode is controlled at 0.40~0.50D junction (D junction is the diameter of the crystallizer), and air cooling is performed after smelting is completed.

[0029] Step 5: When the furnace temperature for charging the steel ingot is below 500℃, it should be kept at that temperature for at least 3 hours after entering the furnace; when the steel ingot is heated to 800-850℃, it should be preheated at a rate of <100℃ / h for a duration of more than 3.0 hours; after preheating, the steel ingot should be heated to the initial forging temperature of 1190±10℃ at a rate of <100℃ / h for a duration of more than 5.0 hours.

[0030] Step 6: To prevent cracks from forming during the upsetting process of the steel ingot, the round steel ingot is pre-deformed and elongated, with the forging ratio controlled between 1.05 and 1.10, and the surface free of obvious indentations and protrusions. Before forging, the manipulator jaws, as well as the hammer, anvil, platform, etc., that come into contact with the forging workpiece, all need to be preheated to a preheating temperature ≥200℃.

[0031] Step 7: Use the "three upsetting and six drawing" method for free forging. Before and after each upsetting, the steel ingot needs to be reheated in the furnace, as detailed below:

[0032] S7.1 First, heat the steel ingot to 1200±10℃ and hold for 5.0±0.5 hours. Before forging, the manipulator jaws, hammers, anvils, platforms, etc., that come into contact with the forging workpiece all need to be preheated to a preheating temperature ≥200℃. Then, the steel ingot undergoes its first upsetting, with the upsetting ratio controlled between 1.80 and 1.85, ensuring the forging surface is free of folding defects.

[0033] S7.2: After reheating in the furnace, the steel ingot is drawn twice: Before the first drawing, the furnace temperature is raised to 1200±10℃ and held for 6.0 hours. The steel ingot is first drawn to square shape using upper and lower flat anvils, and then the diagonal is turned to octagon. The forging ratio is controlled between 1.60 and 1.63.

[0034] Next, a second drawing process is carried out, first drawing it to a square shape, then turning it diagonally to an octagon shape. The forging ratio is controlled at 1.20 to 1.23, the final forging temperature is ≥900℃, and it is then returned to the furnace for reheating.

[0035] S7.3: Then heat the steel ingot to 1190±10℃ and hold for 5.0 hours. Then perform a second upsetting of the billet, with the upsetting ratio controlled at 1.80~1.85, and then return it to the furnace for heating.

[0036] S7.4: After reheating in the furnace, the steel ingot is drawn twice: Before the third drawing, the steel ingot is heated to 1190±10℃ and held for 6.0 hours. The steel ingot is first drawn to square shape using an upper and lower flat anvil, and then the diagonal is turned to octagon. The forging ratio is controlled at 1.60~1.63.

[0037] Next, a second stretching process is carried out, first stretching it to a square shape, then bending it diagonally to an octagonal shape, with the forging ratio controlled between 1.20 and 1.23.

[0038] S7.5: Heat the steel ingot to 1180±10℃ and hold for 5.0 hours, then perform the third upsetting, with the upsetting ratio controlled at 1.85~1.90, and then return it to the furnace for reheating.

[0039] S7.6: Heat the furnace to 1180±10℃ and hold for 6.0 hours, then perform two drawing operations:

[0040] The steel ingot is first drawn into a square shape using an anvil with both top and bottom flat edges, and then the diagonal is beveled to an octagon shape, with the forging ratio controlled at 1.65 to 1.70. Then, a second drawing process is performed, first drawing it into a square shape, and then beveling the diagonal to an octagon shape, with the forging ratio controlled at 1.25 to 1.30.

[0041] Step 8: Immediately after forging, immerse the forging in water for ≤3 minutes, with a water immersion temperature ≥850℃, and water cooling for ≥120 minutes until it reaches room temperature.

[0042] Step 9: Preheating before precision forging: The furnace loading temperature of the forging is ≤650℃. After entering the furnace, the temperature is held for no less than 2.0 hours. Then, the temperature is increased to 800~850℃ at ≤100℃ / h and held for no less than 2.0 hours. Then, the temperature is increased to 1120±10℃ at ≤100℃ / h and held.

[0043] Step 10: Preheating followed by precision forging: Specifically, the temperature is held at 1120±10℃ for 4.0 hours, using an R280 hammer forging process, consisting of 4 main deformation passes + 2 finishing passes for elongation, as detailed below:

[0044] Step 10.1: The single-pass pressing amount for the first pass is 40-45mm, the hammer pressing frequency is 170-180 times / min, the feed speed is 3.5-3.8m / min, and the rotation angle is 16.1° / stroke.

[0045] Step 10.2: The single-pass pressing amount of the second pass is 70-80mm, the hammer pressing frequency is 170-180 times / min, the feed speed is 3.8-4.0 / min, and the rotation angle is 16.1° / stroke.

[0046] Step 10.3: The single-pass pressing amount of the third pass is 40-45mm, the hammer pressing frequency is 170-180 times / min, the feed speed is 3.5-3.8 / min, and the rotation angle is 16.1° / stroke.

[0047] Step 10.4: The single-pass pressing amount of the fourth pass is 70-80mm, the hammer pressing frequency is 170-180 times / min, the feed speed is 3.8-4.0 / min, and the rotation angle is 16.1° / stroke.

[0048] Step 10.5: The single-pass pressing amount of the fifth pass is 70-80mm, the hammer pressing frequency is 170-180 times / min, the feed speed is 3.5-3.8 / min, and the rotation angle is 16.1° / stroke.

[0049] Step 10.6: The single-pass reduction of the sixth pass is 3-8mm, the hammer pressing frequency is 220-240 times / min, the feed speed is 3.8-4.0 / min, the rotation angle is 16.1° / stroke, the overall forging ratio is controlled at 2.60-2.65, and the final forging temperature is ≥950℃.

[0050] Step 11: Immediately after precision forging, immerse the forging in water for ≤3 minutes. The water temperature of the forging should be ≥850℃. Water cool for 25-30 minutes, then water cool to room temperature.

[0051] For the edges, 1 / 2R, and center of the forging, check the grain size. The grain size should be greater than or equal to grade 5, and the uniformity should be less than grade 2.

[0052] Example:

[0053] The present invention proposes a forging method for controlling the grain size uniformity of 0Cr16Ni15Mo2V stainless steel, the specific steps of which are as follows:

[0054] Step 1: The chemical composition of 0Cr16Ni15Mo2V is C: 0.05%, Si: 0.50%, S≤0.001%, P≤0.007%, Mn: 1.65%, Ni: 15.40%, Cr: 16.40%, Mo: 2.04%, Ti: 0.38%, V: 0.20%, and total oxygen: 0.0010%.

[0055] Step 2: The specifications of the steel ingot before forging are φ500mm×1300mm.

[0056] Step 3: Vacuum induction melting is performed to obtain a consumable electrode blank;

[0057] The alloy required in step 1 above is placed into a vacuum induction melting furnace. The refining vacuum degree is ≤5Pa, the refining time is ≥50min, and the tapping temperature is controlled at 1520~1600℃.

[0058] Step 4: Grind the surface of the consumable electrode billet produced in the vacuum induction melting furnace until the surface is bright, and then carry out vacuum consumable melting. The melting rate is controlled at 0.40~0.50D junction (D junction is the diameter of the crystallizer in meters), and the melting rate is in kilograms / hour. After smelting, air cool.

[0059] Step 5: Preheating of steel ingots before forging: When the furnace temperature of the steel ingots is below 500℃, they should be kept at that temperature for 3 hours after entering the furnace; when the steel ingots continue to be heated to 800-850℃, preheating should be carried out at a heating rate of <100℃ / h for 4.0 hours; after preheating, the steel ingots should continue to be heated to the initial forging temperature of 1190±10℃ at a heating rate of <100℃ / h for 5.0 hours.

[0060] Step 6: Before forging, the jaws of the manipulator, as well as the hammer, anvil, platform, etc. that come into contact with the forging, are preheated to 200℃.

[0061] Step 7: Roll the steel ingot to a diameter of φ490×1380, with no obvious dents or protrusions on the surface;

[0062] Step 8: Use the "three-upsetting and six-drawing" method for free forging. The specific steps are as follows:

[0063] S8.1: Return the steel ingot to the furnace and heat it to 1200±10℃, holding it at that temperature for 5.0 hours. Before forging, the manipulator jaws, as well as the hammer, anvil, platform, etc., that come into contact with the forging, all need to be preheated to 200℃. Upset the steel ingot to a length of 750mm.

[0064] S8.2: Heat the furnace to 1200±10℃ and hold for 6.0 hours. Use an anvil to first draw the steel ingot to 570×570 square, then bevele the diagonal to 570 octagon; then draw it to 500×500 square, then bevele the diagonal to 500 octagon, with a length of about 1260mm. The final forging temperature is ≥900℃, and the ingot is then returned to the furnace for reheating.

[0065] S8.3: Hold the furnace at 1190±10℃ for 5.0 hours, perform a second upsetting of the billet to 750mm in length, and then return it to the furnace for reheating.

[0066] S8.4: The furnace temperature is raised to 1190±10℃ and held for 6.0 hours. The steel ingot is first drawn to 570×570 square using an anvil, and then the diagonal is turned to 570 octagon. It is then drawn to 500×500 square and the diagonal is turned to 500 octagon, with a length of about 1260mm. The final forging temperature is ≥900℃, and the ingot is returned to the furnace for reheating.

[0067] S8.5: Heat the furnace to 1180±10℃ and hold for 5.0 hours. Then, upset the billet three times to 750 and return it to the furnace for reheating.

[0068] S8.6: The furnace temperature is raised to 1180±10℃ and held for 6.0 hours. The steel ingot is first drawn to 570×570 square using an anvil, and then the diagonal is turned to 570 octagon. It is then drawn to 500×500 square and the diagonal is turned to 500 octagon, with a length of about 1260mm. The final forging temperature is ≥900℃.

[0069] Step 9: Immediately after forging, immerse the forging in water for ≤3 minutes. The water temperature of the forging should be ≥850℃. Cool the forging in water for 180 minutes until it reaches room temperature.

[0070] Step 10: Preheat the steel ingot. The ingot loading temperature should be ≤650℃. After loading into the furnace, hold the temperature for no less than 2.0 hours. Then, increase the temperature at ≤100℃ / h to 800~850℃ and hold for no less than 2.0 hours. Then, increase the temperature at ≤100℃ / h to 1120±10℃ and hold.

[0071] Then it is precision forged into shape, and the specific steps are as follows:

[0072] S10.1: The single-pass pressing amount for the first pass is 40mm, the hammer pressing frequency is 180 times / min, the feed speed is 3.8m / min, and the rotation angle is 16.1° / stroke.

[0073] S10.2: The single-pass pressing amount of the second pass is 80mm, the hammer pressing frequency is 180 times / min, the feed speed is 4.0 / min, and the rotation angle is 16.1° / stroke.

[0074] S10.3: The single-pass pressing amount of the third pass is 40mm, the hammer pressing frequency is 180 times / min, the feed speed is 3.8 / min, and the rotation angle is 16.1° / stroke.

[0075] S10.4: The single-pass pressing amount of the fourth pass is 80mm, the hammer pressing frequency is 180 times / min, the feed speed is 4.0 / min, and the rotation angle is 16.1° / stroke.

[0076] S10.5: The single-pass reduction of the fifth pass is 77mm, the hammer pressing frequency is 180 times / min, the feed speed is 3.8 / min, and the rotation angle is 16.1° / stroke.

[0077] S10.6: The single-pass reduction in the sixth pass is 3mm, the hammer pressing frequency is 240 times / min, the feed speed is 4.0 / min, and the rotation angle is 16.1° / stroke. The forging ratio is controlled between 2.600 and 2.65, and the final forging temperature is ≥950℃.

[0078] Step 11: Immediately after forging, immerse in water and cool for 120 minutes to room temperature.

[0079] Grain size was measured at the edge, 1 / 2R, and center of the forging, and the results were grade 6.5, 6.0, and 5.5, respectively.

[0080] Therefore, it can be seen that the present invention can effectively control the grain size uniformity of 0Cr16Ni15Mo2V stainless steel.

Claims

1. A forging method for controlling the grain size uniformity of 0Cr16Ni15Mo2V stainless steel, characterized in that: After free forging and precision forging, the steel ingot is rapidly water-cooled; the free forging adopts a three-upsetting and six-drawing method, and the precision forging adopts a low-temperature multi-pass method to control the total deformation; the specific steps of the three-upsetting and six-drawing method are as follows: The temperature of the first upsetting is 1200±10℃, and the upsetting ratio is 1.80~1.85; then, after reheating in the furnace, the first and second drawing are carried out, with the drawing preheating temperature at 1200±10℃ and the forging ratios controlled at 1.60~1.63 and 1.20~1.23 respectively. The second upsetting temperature is 1190±10℃, and the upsetting ratio is 1.80~1.

85. After reheating in the furnace, the third and fourth drawing are carried out. The drawing preheating temperature is 1190±10℃, and the forging ratio is controlled at 1.60~1.63 and 1.20~1.23 respectively. The third upsetting temperature is 1180±10℃, and the upsetting ratio is 1.85~1.

90. After reheating in the furnace, the fifth and sixth drawing are carried out. The drawing preheating temperature is 1180±10℃, and the forging ratio is controlled at 1.65~1.70 and 1.25~1.30 respectively. Precision forging includes six passes of lengthening: The reduction amounts for the first to sixth passes are 40–45 mm, 70–80 mm, 40–45 mm, 70–80 mm, 70–80 mm, and 3–8 mm, respectively; the hammer impact frequency for the first to fifth passes is 170–180 times / min, and the hammer impact frequency for the sixth pass is 220–240 times / min; the feed rates for the first to sixth passes are 3.5–3.8 m / min, 3.8–4.0 m / min, 3.5–3.8 m / min, 3.8–4.0 m / min, 3.5–3.8 m / min, and 3.8–4.0 m / min, respectively.

2. The forging method for controlling the grain size uniformity of 0Cr16Ni15Mo2V stainless steel according to claim 1, characterized in that: Before precision forging, the steel ingot is preheated. The ingot loading temperature is ≤650℃, and then the temperature is increased to 800~850℃ at ≤100℃ / h and held. Then the temperature is increased to 1120±10℃ at ≤100℃ / h and held.

3. The forging method for controlling the grain size uniformity of 0Cr16Ni15Mo2V stainless steel according to claim 1, characterized in that: The overall forging ratio of precision forging is controlled between 2.60 and 2.65, and the final forging temperature is ≥950℃.

4. The forging method for controlling the grain size uniformity of 0Cr16Ni15Mo2V stainless steel according to claim 1, characterized in that: Immediately after free forging, the forging is immersed in water for cooling. The immersion time after forging is ≤3 minutes, the immersion temperature of the forging is ≥850℃, the water cooling time is ≥120 minutes, and the water cooling is brought to room temperature.

5. A forging method for controlling the grain size uniformity of 0Cr16Ni15Mo2V stainless steel according to claim 1, characterized in that: Immediately after precision forging, the workpiece should be immersed in water for cooling. The immersion time should be ≤3 minutes, and the immersion temperature should be ≥850℃. After water cooling for 25-30 minutes, the workpiece should be cooled to room temperature.

6. A forging method for controlling the grain size uniformity of 0Cr16Ni15Mo2V stainless steel according to claim 1, characterized in that: Before free forging, the preheated steel ingot is pre-deformed and elongated, with the forging ratio controlled between 1.05 and 1.

10. During preheating, the furnace temperature for charging the steel ingot is below 500℃, and it should be kept at that temperature for more than 3 hours after entering the furnace. The temperature is then increased to 800-850℃ at a rate of less than 100℃ / h, and the preheating time is greater than 3.0 hours. Finally, the temperature is increased to the initial forging temperature of 1190±10℃ at a rate of less than 100℃ / h, and the holding time is greater than 5.0 hours.

7. A forging method for controlling the grain size uniformity of 0Cr16Ni15Mo2V stainless steel according to claim 1, characterized in that: The chemical composition of 0Cr16Ni15Mo2V stainless steel is controlled as follows: C: 0.040~0.080%, Si: 0.30~0.90%, S≤0.010%, P≤0.030%, Mn: 1.30~2.00%, Ni: 14.00~15.50%, Cr: 15.50~17.00%, Mo: 1.90~2.50%, Ti: 0.20~0.60%, V: 0.10~0.30%, Total oxygen: ≤0.0010%.

8. A forging method for controlling the grain size uniformity of 0Cr16Ni15Mo2V stainless steel according to claim 1, characterized in that: The grain size of the forgings is controlled at level 5 or above, and the cross-sectional strength difference is controlled at level 2 or below.

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