Forging method for controlling grain size uniformity of 0Cr16Ni15Mo2V stainless steel

Abstract

The invention relates to a forging method for controlling grain size uniformity of 0Cr16Ni15Mo2V stainless steel, which adopts a free forging and precision forging combined method to manufacture and produce fine-grain and homogenized 0Cr16Ni15Mo2V stainless steel, adopts free forging in a three-upsetting and six-drawing mode, adopts low-temperature multi-pass precision forging to control total deformation, and adopts a quick water cooling method after forging. The grain size of the forge piece is controlled to be more than level 5 and the strength range of the cross section is controlled to be within level 2 through the relation among different upsetting and drawing temperatures and deformation of free forging, deformation of different passes of precision forging, the pressing frequency of a hammer head and the feeding speed.

Description

Technical Field

[0001] The invention belongs to the technical field of stainless steel forging, and in particular relates to a forging method for controlling the uniformity of grain size of 0Cr16Ni15Mo2V stainless steel. Background Art

[0002] 0Cr16Ni15Mo2V stainless steel is mainly used as the main material for nuclear fuel assembly cladding tubes, outer sleeves, wires and rods. The maximum temperature of the fuel element cladding can reach 650℃. At the same time, the deep fuel and the large number of fast neutrons have a great impact, which requires the stainless steel material to have extremely high high-temperature creep performance and radiation resistance. Coarse grains will seriously reduce the high-temperature strength and corrosion resistance of the material, so the design requires the grain size to be ≥5 levels. This type of steel cannot be refined by heat treatment, and it is very difficult to obtain uniform fine-grained steel. In addition, the steel contains elements such as Cr, Ni, and Ti. If the forging temperature and cooling are not properly controlled, corresponding precipitation phases will be generated. Therefore, it is very difficult to consider the grain size refinement and homogenization while considering the precipitation phase. Summary of the invention

[0003] The invention provides a forging method for controlling the uniformity of the grain size of 0Cr16Ni15Mo2V stainless steel, and adopts a free forging + precision forging combined method to manufacture and produce fine-grained and uniform 0Cr16Ni15Mo2V stainless steel.

[0004] In order to solve the above technical problems, the present invention provides a forging method for controlling the uniformity of grain size of 0Cr16Ni15Mo2V stainless steel, characterized in that: the steel ingot is subjected to free forging and fine forging and then rapidly water-cooled; the free forging adopts a three-upsetting and six-drawing method, and the fine 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:

[0005] The temperature of the first upsetting is 1200±10℃, and the upsetting ratio is 1.80~1.85; then the steel is returned to the furnace for preheating for the first and second stretching, and the preheating temperature is 1200±10℃, and the forging ratios are controlled at 1.60~1.63 and 1.20~1.23 respectively;

[0006] The second upsetting temperature is 1190±10℃, the upsetting ratio is 1.80~1.85, and then the steel is returned to the furnace for preheating for the third and fourth drawing. The drawing preheating temperature is 1190±10℃, and the forging ratios are controlled at 1.60~1.63 and 1.20~1.23 respectively;

[0007] The third upsetting temperature is 180±10℃, the upsetting ratio is 1.85-1.90, and then the steel is returned to the furnace for preheating before the fifth and sixth drawing. The drawing preheating temperature is 1180±10℃, and the forging ratios are controlled at 1.65-1.70 and 1.25-1.30 respectively.

[0008] Furthermore, the steel ingot is preheated before fine forging, the steel ingot charging temperature is ≤650°C, then the temperature is increased to 800-850°C at ≤100°C / h and kept warm; then the temperature is increased to 1120±10°C at ≤100°C / h and kept warm; and then six passes of drawing are performed.

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

[0010] Furthermore, the rotation angles of the first to sixth passes are 16.1° / stroke.

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

[0012] Furthermore, after the free forging is completed, the forging is immediately cooled in water, the water immersion time after forging is ≤3 minutes, the water immersion temperature of the forging is ≥850°C, the water cooling time is ≥120 minutes, and the forging is water-cooled to room temperature.

[0013] Furthermore, the forging is immediately cooled in water after fine forging, the water immersion time after forging is ≤3 minutes, the water immersion temperature of the forging is ≥850°C, and the forging is water-cooled for 25 to 30 minutes until it is cooled to room temperature.

[0014] Furthermore, before free forging, the preheated steel ingot is pre-deformed and stretched, and the forging ratio is controlled at 1.05-1.10; during preheating, the charging furnace temperature of the steel ingot is lower than 500°C, and it should be kept warm for more than 3 hours after entering the furnace; the steel ingot is preheated when it continues to be heated to 800-850°C, the heating rate is less than 100°C / h, and the preheating time is greater than 3.0 hours; after the steel ingot is preheated, it is continued to be heated to the initial forging temperature of 1190±10°C, the heating rate is less than 100°C / h, and the holding time is greater 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%, total oxygen: ≤0.0010%.

[0016] Furthermore, before forging, the jaws of the operating machine and the hammer head, anvil and platform in contact with the forging need to be preheated, and the preheating temperature is ≥200°C; the grain size of the forging is controlled above level 5 and the extreme difference in cross-sectional strength is controlled within level 2.

[0017] Beneficial effect: The innovation of the present invention is that the free forging + precision forging combined method can be used to produce fine-grained and homogenized 0Cr16Ni15Mo2V stainless steel. The grain size is homogenized by controlling the temperature and deformation amount during the free forging process and combining the precision forging low-temperature multi-pass uniform deformation, thus solving the current technical problem of homogenizing the grain size of 0Cr16Ni15Mo2V stainless steel.

[0018] The free forging of the present invention adopts a three-upsetting and six-drawing method + a precision forging adopts a low-temperature multi-pass control of the total deformation and a method of rapid water cooling after forging. The key point is the connection between the temperature and deformation of different upsetting and drawing processes in free forging and 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 extreme difference in cross-sectional strength is controlled within level 2.

[0019] This technology has promoted the further improvement of the technical level of forged stainless steel and increased the product added value and market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the relationship between the holding temperature and holding time of the steel ingot in different passes of the free forging process.

[0021] Figure 2 This is the heating relationship diagram between forging heating and holding time during precision forging.

[0022] Figure 3 (a), (b), and (c) are schematic diagrams of the grain size of the steel ingot samples taken at the edge, 1 / 2R, and center after forging, respectively; DETAILED DESCRIPTION

[0023] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below.

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

[0025] Step 1: The chemical composition of 0Cr16Ni15Mo2V stainless steel of the present 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 by vacuum induction melting and vacuum consumables.

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

[0028] Step 4: Before vacuum consumable melting, the surface of the consumable electrode blank produced by the vacuum induction melting furnace must be ground and polished. The melting rate of the vacuum consumable electrode is controlled at 0.40-0.50D knot (D knot is the diameter of the crystallizer), and the smelting is completed with air cooling.

[0029] Step 5: The steel ingot charging furnace temperature is lower than 500°C, and it should be kept warm for more than 3 hours after entering the furnace; the steel ingot is preheated when it continues to heat up to 800-850°C, the heating rate is less than 100°C / h, and the preheating time is greater than 3.0h; after the steel ingot is preheated, it is continued to heat up to the initial forging temperature of 1190±10°C, the heating rate is less than 100°C / h, and the holding time is greater 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 stretched, and the forging ratio is controlled at 1.05-1.10, with no obvious pressure pits or convex edges on the surface. Before forging, the jaws of the operating machine and the hammer head, anvil, platform, etc. that are in contact with the forging need to be preheated, and the preheating temperature is ≥200℃;

[0031] Step 7: Use the "three upsetting and six drawing" method for free forging. The steel ingot needs to be returned to the furnace for preheating before and after each upsetting. The details are as follows:

[0032] S7.1. First, heat the steel ingot to 1200±10℃ and keep it warm for 5.0±0.5 hours. Before forging, the jaws of the operating machine and the hammer head, anvil, platform, etc. in contact with the forging need to be preheated, and the preheating temperature is ≥200℃. Then, the steel ingot is subjected to the first upsetting, and the upsetting ratio is controlled at 1.80~1.85, and there is no folding defect on the surface of the forging blank;

[0033] S7.2: After returning to the furnace for heating, two stretching operations are performed: before the first stretching, the furnace temperature is raised to 1200±10℃ and kept warm for 6.0 hours. The upper and lower flat anvils are used to first stretch the steel ingot to a square, and then the diagonal lines are inverted to octagonal shapes. The forging ratio is controlled at 1.60-1.63.

[0034] Then the secondary drawing is carried out, first drawing to a square, then inverting the diagonal to an octagonal shape, the forging ratio is controlled at 1.20-1.23, the final forging temperature is ≥900℃, and the furnace is returned for heating.

[0035] S7.3: Then the steel ingot is heated to 1190±10℃ and kept at this temperature for 5.0 hours, and the billet is subjected to secondary upsetting with the upsetting ratio controlled at 1.80-1.85, and then returned to the furnace for heating.

[0036] S7.4: After returning to the furnace for heating, two stretching operations are performed: before the third stretching, the steel ingot is heated to 1190±10℃ and kept warm for 6.0 hours. The steel ingot is first stretched to a square using upper and lower flat anvils, and then the diagonal is inverted to an octagonal shape. The forging ratio is controlled at 1.60-1.63.

[0037] Then the second stretching is carried out, first stretching to a square, then inverting the diagonal to an octagonal shape, and the forging ratio is controlled at 1.20-1.23.

[0038] S7.5: Heat the steel ingot to 1180±10℃ and keep it at this temperature for 5.0 hours, perform the third upsetting, control the upsetting ratio at 1.85~1.90, and then return to the furnace for heating.

[0039] S7.6: Raise the furnace temperature to 1180±10℃ and keep it for 6.0 hours, and perform two stretching operations:

[0040] The steel ingot is first stretched to a square shape using upper and lower flat anvils, and then the diagonal shape is turned to an octagonal shape, and the forging ratio is controlled at 1.65 to 1.70. Then the steel ingot is stretched for the second time, first stretched to a square shape, and then the diagonal shape is turned to an octagonal shape, and the forging ratio is controlled at 1.25 to 1.30.

[0041] Step 8: After forging, immediately cool in water. The water immersion time after forging is ≤3 minutes. The water immersion temperature of the forging is ≥850℃. The water cooling time is ≥120 minutes, and the forging is cooled to room temperature.

[0042] Step 9: Preheating before fine forging: the charging temperature of the forging is ≤650℃, and it is kept warm for not less than 2.0 hours after entering the furnace, and then the temperature is increased to 800-850℃ at ≤100℃ / h and kept warm for not less than 2.0 hours; then the temperature is increased to 1120±10℃ at ≤100℃ / h and kept warm.

[0043] Step 10: Preheating and finishing forging: Specifically, keep the temperature at 1120±10℃ for 4.0 hours, use R280 hammer forging, and divide into 4 main deformation passes + 2 finishing passes for drawing, as follows:

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

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

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

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

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

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

[0050] Step 11: After fine forging, immediately put it into water for cooling. The water immersion time after forging is ≤3 minutes, the water immersion temperature of the forging is ≥850℃, and water cooling is carried out for 25 to 30 minutes until it reaches room temperature.

[0051] Check the grain size of the edge, 1 / 2R and center of the forging. The grain size is greater than or equal to level 5 and the uniformity is less than level 2.

[0052] Example:

[0053] The present invention proposes a forging method for controlling the uniformity of grain size of 0Cr16Ni15Mo2V stainless steel, and the specific steps 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%, total oxygen: 0.0010%;

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

[0056] Step 3: performing vacuum induction melting to obtain a consumable electrode blank;

[0057] The alloy required in step 1 above is placed in a vacuum induction melting furnace, the refining vacuum 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 blank produced by the vacuum induction melting furnace, expose the surface to light, and then perform vacuum consumable melting. The melting rate is controlled at 0.40-0.50D knot (D knot is the diameter of the crystallizer, in meters), the melting rate unit is kilograms / hour, and the smelting is completed by air cooling.

[0059] Step 5: Preheating of the steel ingot before forging: The charging furnace temperature of the steel ingot is lower than 500℃, and it should be kept warm for 3 hours after entering the furnace; the steel ingot continues to be preheated when it is heated to 800-850℃, the heating rate is less than 100℃ / h, and the preheating time is 4.0h; after the steel ingot is preheated, it continues to be heated to the initial forging temperature of 1190±10℃, the heating rate is less than 100℃ / h, and the holding time is 5.0 hours;

[0060] Step 6: Before forging, the jaws of the operating machine and the hammer head, anvil, platform, etc. that are in contact with the forging are preheated at 200°C.

[0061] Step 7: Roll the steel ingot to φ490×1380, with no obvious pressure pits and convex edges 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℃ for 5.0 hours. Before forging, the jaws of the operating machine and the hammer head, anvil, platform, etc. in contact with the forging need to be preheated at 200℃. Upset the steel ingot to 750mm in length.

[0064] S8.2: The furnace temperature is raised to 1200±10℃ and kept at this temperature for 6.0 hours. The steel ingot is first stretched to 570×570 square by upper and lower flat anvils, and the diagonal is 570 octave; then stretched to 500×500 square, and the diagonal is 500 octave, with a length of about 1260mm. The final forging temperature is ≥900℃, and the steel ingot is returned to the furnace for heating.

[0065] S8.3: Keep the furnace temperature at 1190±10℃ for 5.0 hours, perform secondary upsetting on the billet, upset the billet length to 750mm, and return to the furnace for heating.

[0066] S8.4: The furnace temperature is raised to 1190±10℃ and kept at this temperature for 6.0 hours. The steel ingot is first stretched to 570×570 square by upper and lower flat anvils, and the diagonal is 570 octave; then stretched to 500×500 square, and the diagonal is 500 octave, with a length of about 1260mm. The final forging temperature is ≥900℃, and the steel ingot is returned to the furnace for heating.

[0067] S8.5: The furnace temperature is raised to 1180±10℃ and kept at this temperature for 5.0 hours. The billet is upset three times, and the billet is upset to 750℃ and returned to the furnace for heating.

[0068] S8.6: The furnace temperature is raised to 1180±10℃ and kept at this temperature for 6.0 hours. The steel ingot is first stretched to 570×570 square and the diagonal to 570 octave by using upper and lower flat anvils; then stretched to 500×500 square and the diagonal to 500 octave, with a length of about 1260mm. The final forging temperature is ≥900℃.

[0069] Step 9: After forging, cool the forging in water immediately. The water immersion time after forging is ≤3 minutes. The water immersion temperature of the forging is ≥850℃. Cool the forging in water for 180 minutes to room temperature.

[0070] Step 10: The steel ingot is heated to a temperature of ≤650°C. After entering the furnace, it is kept warm for at least 2.0 hours. Then, the temperature is raised to 800-850°C at a rate of ≤100°C / h and kept warm for at least 2.0 hours. Then, the temperature is raised to 1120±10°C at a rate of ≤100°C / h and kept warm.

[0071] Then the precision forging is performed. The specific steps are as follows:

[0072] S10.1: The first pass has a single pass reduction of 40 mm, a hammer pressing frequency of 180 times / min, a feed speed of 3.8 m / min, and a rotation angle of 16.1° / stroke.

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

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

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

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

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

[0078] Step 11: After forging, put it into water immediately and cool it down to room temperature for 120 minutes.

[0079] Samples were taken from the edge, 1 / 2R, and center of the forging for grain size testing, and the results were 6.5, 6.0, and 5.5, respectively.

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

Claims

1. A forging method for controlling the uniformity of grain size of 0Cr16Ni15Mo2V stainless steel, characterized in that: After the steel ingot is subjected to free forging and fine forging, it is rapidly water-cooled; the free forging adopts a three-upsetting and six-drawing method, and the fine 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 the steel is returned to the furnace for preheating for the first and second stretching, and the preheating temperature is 1200±10℃, and the forging ratios are controlled at 1.60~1.63 and 1.20~1.23 respectively; The second upsetting temperature is 1190±10℃, the upsetting ratio is 1.80~1.85, and then the steel is returned to the furnace for preheating for the third and fourth drawing. The drawing preheating temperature is 1190±10℃, and the forging ratios are controlled at 1.60~1.63 and 1.20~1.23 respectively; The third upsetting temperature is 180±10℃, the upsetting ratio is 1.85-1.90, and then the steel is returned to the furnace for preheating before the fifth and sixth drawing. The drawing preheating temperature is 1180±10℃, and the forging ratios are controlled at 1.65-1.70 and 1.25-1.30 respectively.

2. A forging method for controlling the uniformity of grain size of 0Cr16Ni15Mo2V stainless steel according to claim 1, characterized in that: The steel ingot is preheated before fine forging, the charging temperature of the steel ingot is ≤650℃, and then the temperature is raised to 800-850℃ at ≤100℃ / h and kept warm; then the temperature is raised to 1120±10℃ at ≤100℃ / h and kept warm; then six passes of drawing are carried out.

3. A forging method for controlling the grain size uniformity of 0Cr16Ni15Mo2V stainless steel according to claim 2, characterized in that: During fine forging: the reduction amounts of the first to sixth passes are 40-45mm, 70-80mm, 40-45mm, 70-80mm, 70-80mm, 3-8mm respectively; the frequency of hammer pressing for the first to fifth passes is 170-180 times / min, and the frequency of hammer pressing for the sixth pass is 220-240 times / min; the feed speeds of the first to sixth passes are 3.5-3.8m / min, 3.8-4.0 / min, 3.5-3.8 / min, 3.8-4.0 / min, 3.5-3.8 / min, 3.8-4.0 / min respectively.

4. A forging method for controlling the grain size uniformity of 0Cr16Ni15Mo2V stainless steel according to claim 3, characterized in that: The rotation angle of the first to sixth passes is 16.1° / stroke.

5. A 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 at 2.60-2.65, and the final forging temperature is ≥950℃.

6. A forging method for controlling the uniformity of grain size of 0Cr16Ni15Mo2V stainless steel according to claim 1, characterized in that: After free forging, the forgings shall be immediately cooled in water. The water immersion time after forging shall be ≤3 minutes, the water immersion temperature of the forgings shall be ≥850℃, and the water cooling shall be ≥120 minutes until the forgings are cooled to room temperature.

7. A forging method for controlling the uniformity of grain size of 0Cr16Ni15Mo2V stainless steel according to claim 1, characterized in that: After fine forging, immediately put it into water for cooling. The water immersion time after forging is ≤3 minutes, the water immersion temperature of the forging is ≥850℃, and water cooling is carried out for 25 to 30 minutes, and then water cooling is carried out to room temperature.

8. A forging method for controlling the uniformity of grain size of 0Cr16Ni15Mo2V stainless steel according to claim 1, characterized in that: Before free forging, the preheated steel ingot is pre-deformed and stretched, and the forging ratio is controlled at 1.05-1.10; during preheating, the furnace temperature of the steel ingot is lower than 500°C, and it should be kept warm for more than 3 hours after entering the furnace; the steel ingot is preheated when it continues to heat up to 800-850°C, the heating rate is less than 100°C / h, and the preheating time is greater than 3.0h; after the steel ingot is preheated, it continues to heat up to the initial forging temperature of 1190±10°C, the heating rate is less than 100°C / h, and the holding time is greater than 5.0 hours.

9. 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%.

10. A forging method for controlling the grain size uniformity of 0Cr16Ni15Mo2V stainless steel according to claim 1, characterized in that: Before forging, the jaws of the operating machine and the hammer, anvil and platform in contact with the forging need to be preheated, and the preheating temperature should be ≥200℃; the grain size of the forging should be controlled above level 5 and the extreme difference of cross-sectional strength should be controlled within level 2.

Images