CN110935827A - Forging method of large-specification fine-grain austenitic gas valve steel SNCrW - Google Patents
Forging method of large-specification fine-grain austenitic gas valve steel SNCrW Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/002—Hybrid process, e.g. forging following casting
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/008—Incremental forging
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
- B21K29/00—Arrangements for heating or cooling during processing
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0075—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rods of limited length
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
- C22C33/06—Making ferrous alloys by melting using master alloys
Abstract
The invention discloses a method for forging large-specification fine-grain austenitic gas valve steel SNCrW, and aims to solve the problems of serious segregation of primary carbides of an as-cast structure of a steel ingot, massive precipitation of secondary carbides at corners of a blank and large-scale core structure. The technical scheme of the invention is as follows: the electroslag ingot with qualified chemical components is produced by adopting an EAF/non-vacuum induction furnace + LF + VOD/VHD + ESR smelting process, and the problems of the cast structure of the steel ingot are solved by adopting a radial and rapid forging combined forging method through high-temperature homogenization treatment before forging, billet heating temperature, billet reburning time, upsetting amount, drawing-out pressing amount, deformation amount and deformation mode of each fire and control of the length of a radial forging billet. The invention has the beneficial effects that: the product is large in size, the fine-grained austenitic stainless steel SNCrW bar is qualified in macrostructure, the grain size is more than 6 grade, the flaw detection reaches A grade required by GB/T4162, the requirements of gas valve manufacturing plants in China are met, and the localization of the SNCrW bar is realized.
Description
Technical Field
The invention belongs to the field of hot working of metal materials, and particularly relates to a forging method of a large-size (phi 85 mm-phi 120mm) fine-grained austenitic stainless steel SNCrW bar for an air valve.
Background
The SNCrW belongs to austenitic heat-resistant stainless steel, a forged and rolled room-temperature structure is austenite and carbide, and the SNCrW has high strength, plasticity and toughness after solid solution and aging treatment, and simultaneously has excellent high-temperature fatigue strength and gas corrosion resistance, and is suitable for manufacturing low-speed diesel engine air valve products with high heat strength and corrosion resistance requirements.
The good balance of properties of SNCrW steel is achieved by the need for a uniform structure which is primarily characterized by a high content of carbides, including primary carbides in the as-cast structure and secondary carbides precipitated from the austenitic matrix. The distribution and grain size of carbide have great influence on the structure and performance of steel, so that the primary carbide is fully crushed, the grain size is uniformly refined, and the secondary carbide is dispersed and precipitated in the hot working process. However, the contents of C, Cr and W in the SNCrW steel are high, so that primary carbides are seriously segregated; the heat conductivity coefficient is large, the temperature of the corner of the blank is quickly reduced, and secondary carbides are quickly precipitated and are in large quantity; the core structure is thick; the defects of low-power coarse crystals, elongated grains with aggregated carbides, improper ultrasonic flaw detection and the like are easy to appear on bars in a forged and rolled state. Therefore, how to ensure that the primary carbide is fully crushed, the grain size is uniformly refined and the secondary carbide is uniformly dispersed and precipitated in the hot working process of the SNCrW steel becomes a key problem of hot working.
At present, SNCrW air valve steel small-specification rolled bars have high rolling speed due to large processing ratio and small temperature drop of blank corners, and the microscopic structures at home and abroad can reach better levels; a large-size bar (not less than phi 140mm) is reformed into an air valve product with the thickness of less than 80mm by an air valve manufacturing plant, the requirement on the organization uniformity of the bar is not high, and the production difficulty is not high.
For bars with larger specifications (phi 85 mm-phi 120mm), an air valve manufacturing factory adopts a mode of directly upsetting a disc part to produce the air valve, and the requirements on the structure of the raw material bar are extremely high. Foreign special steel mills can produce bars with qualified macrostructure, 6-grade grain size and mechanical property meeting the use requirement by adopting a rolling process; the domestic special steel mill is limited by the specification and the deformation mode of the hole pattern of the rolling mill, and can not roll qualified bars with larger specification, and the raw materials of the domestic gas valve manufacturing plant all depend on imported SNCrW bars for many years. With the requirement of the localization process of raw materials, the forging method for searching a large-size fine-grain SNCrW bar is urgent.
Disclosure of Invention
The invention discloses a forging method of fine-grain austenitic gas valve steel SNCrW, and aims to solve the problems of serious segregation of primary carbides of an as-cast structure of a steel ingot, massive precipitation of secondary carbides at corners of a blank and large-sized core structure.
In order to achieve the purpose, the invention adopts the technical scheme that:
and adopting an EAF/non-vacuum induction furnace + LF + VOD/VHD + ESR smelting process to produce an electroslag ingot with qualified chemical components. The method comprises the steps of homogenizing at high temperature before forging, controlling the heating temperature of a steel billet, the reheating time of the steel billet, the upsetting reduction, the elongation reduction, the deformation per fire, the deformation mode and the length of a radial forging billet, and producing the grade A SNCrW bar which has qualified macrostructure and grain size of more than 6 and meets the requirements of GB/T4162 by ultrasonic flaw detection.
The method comprises the following specific process steps:
firstly, adopting an EAF/non-vacuum induction furnace, LF + VOD/VHD + ESR method to smelt an electroslag ingot, and homogenizing the steel ingot;
1, EAF: the furnace burden comprises scrap steel, pig iron, the steel return and the like, and the tapping temperature (T) is not lower than 1630 ℃;
2, LF furnace: adding carbon powder, silicon-carbon powder and aluminum powder to an LF station for deoxidation, feeding electric slag for more than 10min, adding an alloy material, and adjusting the components to be proper;
VOD/VHD furnace: adding deoxidizer aluminum powder and calcium-silicon block along with slag (lime and fluorite) after VOD oxygen blowing, vacuum degassing to a vacuum degree of not more than 67Pa, and keeping for not less than 10 min; finely adjusting the components to a control range, and pouring the consumable electrode rod at a tapping temperature (T) of 1490-1510 ℃;
4. using CaF2：Al2O3: CaO 63: 27: 10 slag system adsorbs impurities, molten steel is purified, and electroslag ingot with phi 480mmX (1200-1300) mm is smelted;
5. before forging, the electroslag ingot is subjected to high-temperature homogenization treatment at 1235-1250 ℃ for over 40 h.
Secondly, forging the blank;
the forging deformation adopts a multi-fire forging process, wherein the diameter forging finished material is controlled within 7m of the blanking length of the bar according to the specification of the bar finished product by combining the forging ratio of a diameter forging machine, the final forging temperature of the bar is more than 920 ℃, and the whole forging process can be divided into 5 steps:
1. quick forging and upsetting: keeping the heating temperature of the electroslag ingot after high-temperature homogenization treatment at 1200-1220 ℃ for 2-4 h, then carrying out primary upsetting operation by a rapid forging machine, wherein the upsetting reduction is 300-400 mm, the 80mm reduction is elongated to 450mm octagonal section, a clamp handle is arranged at the end of a bottom pad, the bottom pad is returned to the furnace for heat preservation, and the surface temperature is 1200 ℃ for 2-3 h;
2. quick forging and drawing out: the quick forging machine octagonal forging process is used for drawing out an octagonal section of 360-380 mm, the reduction amount is 70-120 mm, and the final forging temperature of the corner is controlled to be higher than 920 ℃; filling an end pressure clamp handle, returning the steel billets to the furnace after material distribution, and keeping the temperature for 2-2.5 h at the surface temperature of 1200 ℃;
3. quick forging and drawing out: the quick forging machine octagonal forging process draws to an octagonal section of 280 mm-310 mm, the reduction is 70 mm-120 mm, and the final forging temperature of the corner part is controlled to be higher than 920 ℃; returning and preserving heat, and preserving the heat for 2-2.5 h at the surface temperature of 1180 ℃;
4. quick forging and cogging: drawing out an octagonal section of 190-220 mm by a rapid forging machine, wherein the section is a hexagon section, the rolling reduction is 70-120 mm, the final forging temperature of the corner is controlled to be higher than 920 ℃, the length of a blank is 1.5-2.1 m, the temperature of a chamber furnace of a through diameter forging machine is kept, and the surface temperature is 1160 ℃ for 2-2.5 h;
5. radial forging to form a material: and (3) after the blank is discharged from the furnace, heating the blank by using a compensation furnace, preserving heat for 10min at 1140-1150 ℃, and forming the blank by adopting an austenitic stainless steel general procedure through a radial forging machine.
The innovation points of the invention are as follows:
according to the prior equipment level in China, an electroslag ingot is smelted by adopting an EAF/non-vacuum induction furnace, LF, VOD/VHD and ESR, and through the control of a forging process, radial and rapid forging are combined to produce a high-quality gas valve steel bar with qualified macroscopic structure, uniform microstructure and qualified flaw detection.
The invention of the technical scheme is as follows:
(1) the intermediate blank is re-burnt at high temperature for a long time to ensure that the carbide precipitated at the corner is fully dissolved;
(2) reasonably controlling the deformation and drawing reduction per fire, ensuring that the tissues are fully crushed, and reducing the precipitation of carbides at the corners of the intermediate blank, wherein the final forging temperature of the corners is higher than 920 ℃;
(3) the rapid forging machine performs octagonal opening process, and is finally stroked into ten hexagons and then heated by a radial forging chamber furnace, so that the rapid cooling of a convex angle in the radial forging blank transferring process before radial forging forming is avoided;
(4) according to the forging ratio of the radial forging machine and the length of the radial forging blank, the size of the radial forging blank is controlled to be 1.5-2.1 m, the length of the bar is controlled within 7m, and the finish forging temperature of the bar is guaranteed to be higher than 920 ℃.
The invention has the beneficial effects that: the large-size fine-grained austenitic stainless steel SNCrW bar is produced by adopting a radial and rapid forging combined forging method, the low-order structure is qualified, the grain size is more than 6 grade, the flaw detection reaches A grade required by GB/T4162, the requirements of domestic gas valve manufacturing plants are met, and the localization of the large-size fine-grained austenitic stainless steel SNCrW is realized.
Drawings
FIG. 1 is a photograph of macrostructures of example 1;
FIG. 2 is a photograph (100X) of a grain size of a high magnification structure of example 1;
FIG. 3 is a photograph of macrostructures of example 2;
FIG. 4 is a photograph (100X) of a grain size of a high magnification structure of example 2;
FIG. 5 is a photograph of macrostructures of example 3;
FIG. 6 is a photograph (100X) of a grain size of a high magnification structure in example 3.
Detailed Description
The invention is described in detail below with reference to the accompanying drawings and the detailed description.
Examples 1 to 3 the following processes were carried out together:
⑴ EAF furnace burden is composed of scrap steel, pig iron, and steel return, etc., and the tapping temperature T is not less than 1630 ℃;
⑵ adding carbon powder, silicon-carbon powder and aluminum powder into LF furnace for deoxidation, and adjusting chemical components to be appropriate;
⑶ adding lime and fluorite after oxygen blowing in a VOD furnace, deoxidizing by adopting aluminum powder and calcium-silicon blocks, and pouring a consumable electrode bar at the temperature of 1490-1510 ℃;
⑷ ESR furnace adopts CaF2, Al2O3, CaO 63, 27 and 10 slag system for smelting, and casting phi 480mmX (1200-1300) mm electroslag ingot;
⑸ the electroslag ingot is treated by high temperature homogenization treatment at 1235-1250 ℃ for over 40 h.
Example 1
Producing the SNCrW round steel with the size of phi 88 mm.
1. Smelting and producing SNCrW (strontium-chromium-tungsten) phi 480mm electroslag ingots with qualified chemical components in different plants;
2. keeping the temperature of the electroslag ingot subjected to high-temperature homogenization at 1200 ℃ for 2 hours, and then discharging and forging;
3. upsetting operation is carried out by a quick forging machine, upsetting reduction is 300mm, a double-end forging mode is adopted, the reduction of 80mm is drawn out to be 450mm octagonal section, a clamp handle is arranged at the end of a bottom pad, and the temperature is kept for 3h at 1200 ℃ through a furnace returning and reburning system;
4. drawing out an octagonal section of 360mm by a quick forging machine in an octagonal beating process, wherein the first step is carried out by pressing to a ruler of 360mm, the second step is carried out by drawing out a 120mm reduction, the third step and the fourth step are carried out by pressing to a ruler of 360mm and chamfering, the subsequent steps are shaped according to the blank size of 360mm, the corner finish forging temperature is 925 ℃, then, filling an end pressing clamp handle, cutting a billet, returning to a furnace for heat preservation, and carrying out heat preservation for 2h at the surface temperature of 1200 ℃;
5. drawing out an octagonal section of 280mm by a quick forging machine in an octagonal beating process, wherein the first time is pressed to 280mm of a ruler, the second time is drawn out with 120mm of rolling reduction, the third time and the fourth time are pressed to 280mm of the ruler for chamfering, the subsequent times are shaped according to the size of a blank, and the final forging temperature of the corner part is 930 ℃; returning the billet steel at the surface temperature of 1180 ℃ and preserving heat for 2 hours;
6. the quick forging machine is used for drawing and cogging in an octagonal drawing process to 190mm sixteen-angle cross sections, wherein the first time is pressed to 190mm of a ruler, the second time is drawn out with 120mm of rolling reduction, the third time and the fourth time are pressed to 190mm of a ruler for chamfering, the subsequent times are shaped according to 190mm of a blank size, the corner finish forging temperature is 920 ℃ and 4, each section of steel billet is cut into 1550mm multiplied by 2 sections, a cutting pliers is used for conducting post radial forging machine chamber type furnace heat preservation, and the surface temperature is 1160 ℃ for heat preservation for 2 hours;
7. keeping the temperature of the blank for 10min at 1150 ℃ by using a compensating furnace after the blank is discharged from the furnace, forming the blank by using a radial forging machine by adopting an austenitic stainless steel general program, wherein the finish forging temperature is 930 ℃, and the length is 5.8 m;
8. after forging, the bar is qualified by the macrostructure shown in figure 1, the grain size is 7 grade, the grain size picture (100X) of the high microstructure is shown in figure 2, and the flaw detection GB/T4162 and A grade are obtained.
Example 2
Producing the SNCrW round steel with the size of phi 100 mm.
1. Smelting and producing SNCrW (strontium-chromium-tungsten) phi 480mm electroslag ingots with qualified chemical components in different plants;
2. keeping the temperature of the electroslag ingot subjected to high-temperature homogenization at 1210 ℃ for 3 hours, and then discharging and forging;
3. upsetting operation is carried out by a quick forging machine, upsetting reduction is 350mm, a double-end forging mode is adopted, the reduction of 80mm is drawn out to be 450mm octagonal section, a clamp handle is arranged at the end of a bottom pad, and the temperature is kept for 2.5 hours at 1200 ℃ through a furnace returning and reburning system;
4. drawing to 370mm octagonal section by a quick forging machine octagonal beating process, wherein the first time is pressed to 370mm of a ruler, the second time is drawn to be long by 120mm of reduction, the third time and the fourth time are pressed to 370mm of a ruler for chamfering, the subsequent time is shaped according to 370mm of blank size, the final forging temperature of the corner is 925 ℃, then an end pressing clamp handle is filled, the steel billet is returned to a furnace for heat preservation after 1/3+2/3 is cut off partially, and the surface temperature is 1200 ℃ for heat preservation for 2.5 hours;
5. drawing out an octagonal section of 280mm by a quick forging machine in an octagonal forging process, wherein the first step is to press a ruler to 290mm, the second step is to draw out a 120mm reduction, the third step and the fourth step are to press a ruler to 290mm for chamfering, the subsequent steps are to be shaped according to the blank size of 290mm, and the final forging temperature of the corner part is 925 ℃; returning the billet steel at the surface temperature of 1180 ℃ and preserving heat for 2.5 hours;
6. the quick forging machine is used for drawing and cogging the section of a 200mm hexagon by an octagonal drawing process, wherein the first time is pressed to 200mm of a ruler, the second time is drawn by 120mm of rolling reduction, the third time and the fourth time are pressed to 200mm of a ruler for chamfering, the subsequent time is shaped according to 200mm hexagon of blank size, the final forging temperature of the corner is 930 ℃, 4, the middle 2/3 steel billet is cut into 1700mm multiplied by 2 sections, the cogging length of 1/3 steel billet is 1750mm, the steel billet is subjected to cutting pliers and then passes through a radial forging machine chamber furnace for heat preservation, and the surface temperature is 1160 ℃ for heat preservation for 2 h;
7. keeping the temperature of the blank for 10min at 1145 ℃ by using a compensating furnace after the blank is discharged, forming the blank by using a radial forging machine by adopting an austenitic stainless steel general procedure, wherein the finish forging temperature is 930 ℃, and the length is 5.9 m;
8. after forging, the bar is qualified by the macrostructure shown in figure 3, the grain size is 6 grade, the grain size picture (100X) of the high microstructure is shown in figure 4, and the flaw detection GB/T4162 and A grade are obtained.
Example 3
Producing the SNCrW round steel with the size of phi 115 mm.
1. Smelting and producing SNCrW (strontium-chromium-tungsten) phi 480mm electroslag ingots with qualified chemical components in different plants;
2. keeping the temperature of the electroslag ingot subjected to high-temperature homogenization at 1220 ℃ for 4 hours, and then discharging and forging;
3. upsetting operation is carried out by a quick forging machine, upsetting reduction is 350mm, a double-end forging mode is adopted, the 80mm reduction is drawn out to be 450mm octagonal section, a clamp handle is arranged at the end of a bottom pad, and the temperature is kept for 2h at 1200 ℃ through a furnace returning and reburning system;
4. drawing to 380mm octagonal section by a quick forging machine octagonal beating process, wherein the first time is pressed to 380mm of a ruler, the second time is drawn to length with 120mm reduction, the third time and the fourth time are pressed to 380mm of a ruler for chamfering, the subsequent times are shaped according to 380mm of blank size, the corner finish forging temperature is 930 ℃, then filling an end pressing clamp handle, returning to a furnace for heat preservation after the billet is 1/3+2/3 is partially cut, and preserving the heat for 2h at the surface temperature of 1200 ℃;
5. drawing out an octagonal section of 310mm by a quick forging machine in an octagonal forging process, wherein the first step is to press a ruler for 310mm, the second step is to draw out a 120mm reduction, the third step and the fourth step are to press a ruler for 310mm chamfering, the subsequent steps are to shape according to the blank size of 280mm, and the final forging temperature of the corner part is 925 ℃; returning the billet steel at the surface temperature of 1180 ℃ and preserving heat for 2 hours;
6. the quick forging machine is used for drawing and cogging in an octagonal drawing process to a 220 mm-sixteen-angle section, wherein the first time is pressed to a ruler of 220mm, the second time is drawn to be long by 120mm rolling reduction, the third time and the fourth time are pressed to a ruler of 220mm chamfering, the subsequent time is shaped according to 220 mm-sixteen angles of blank size, the final forging temperature of the corner is 925 ℃, the lengths of two sections of blanks are 2050mm, the billet cutter is used for holding the temperature of a post-pass forging machine chamber furnace, and the surface temperature is 1160 ℃ for holding 2.5 hours;
7. keeping the temperature of 1140 ℃ for 10min by using a compensating furnace after the blank is discharged from the furnace, forming the blank by adopting an austenitic stainless steel general procedure by using a radial forging machine, wherein the finish forging temperature is 930 ℃, and the length is 6.4 m;
8. after the bar is forged, the low-magnification structure is qualified and shown in the attached figure 5, the grain size is grade 6, a high-magnification structure grain size picture (100X) is shown in the attached figure 6, and the flaw detection result GB/T4162 is grade A.
Claims (4)
1. A forging method of large-specification fine-grain austenitic gas valve steel SNCrW is characterized in that a forged electroslag ingot is smelted by adopting an EAF/non-vacuum induction furnace + LF + VOD/VHD + ESR method, and the steel ingot is homogenized; the method is characterized in that: according to the forging method, the multi-fire forging process is adopted, wherein the diameter forging finished material is controlled within 7m of the blanking length of a bar according to the specification of the bar finished product by combining the forging ratio of a diameter forging machine, the final forging temperature of the bar is higher than 920 ℃, and the whole forging process can be divided into 5 steps:
⑴ quick forging, upsetting and drawing, namely, keeping the heating temperature of the electroslag ingot after high-temperature homogenization at 1200-1220 ℃ for 2-4 h, then carrying out one-time upsetting operation by a quick forging machine, wherein the upsetting reduction is 300-400 mm, the 80mm reduction is drawn to 450mm octagonal, a clamp handle is arranged at the end of a bottom pad, returning to the furnace for keeping the temperature, and keeping the surface temperature at 1200 ℃ for 2-3 h;
⑵ quick forging and drawing out, wherein the quick forging machine is used for forging an octagon to 360-380 mm octagon, the rolling reduction is 70-120 mm, the final forging temperature of the corner is controlled to be more than 920 ℃, an end pressing clamp is filled, the billet is divided and then is returned to the furnace for heat preservation, and the surface temperature is 1200 ℃ for heat preservation for 2-2.5 h;
⑶ quick forging and drawing out, namely drawing out an octagonal block of 280-310 mm by a quick forging machine in an octagonal beating process, controlling the final forging temperature of corners to be more than 920 ℃, returning to a furnace and preserving heat, and preserving heat at the surface temperature of 1180 ℃ for 2-2.5 hours;
⑷ quick forging and cogging, namely, the quick forging machine is used for forging octagonal, the cogging is drawn to 190-220 mm decahexagonal, the reduction is 70-120 mm, the final forging temperature of the corner is controlled to be higher than 920 ℃, the length of the blank is 1.5-2.1 m, the temperature of the through diameter forging machine is kept in a chamber furnace, and the surface temperature is 1160 ℃, and the temperature is kept for 2-2.5 h;
⑸ radial forging, namely, after the blank is taken out of the furnace, heating the blank by using a compensation furnace, and carrying out heat preservation for 10min at 1140-1150 ℃, wherein the radial forging machine adopts an austenitic stainless steel general procedure to form the material.
2. The forging method of large-specification fine-grained austenitic gas valve steel SNCrW according to claim 1, wherein a forged electroslag ingot is smelted by adopting an EAF/non-vacuum induction furnace + LF + VOD/VHD + ESR method, and the ingot is homogenized; the method is characterized in that: the forging method comprises the following steps:
⑴ upsetting operation is carried out by a quick forging machine, the upsetting amount is 300mm, a two-end forging mode is adopted, the 80mm reduction is drawn out to be an octagon of 450mm, a clamp handle is arranged at the end of a bottom pad, and the temperature is kept for 3h at 1200 ℃ through a furnace returning and reburning system;
⑵ quick forging machine octagonal beating process is drawn to 360mm octagonal, wherein the first time is pressed to 360mm of a ruler, the second time is drawn to length with 120mm rolling reduction, the third time and the fourth time are pressed to 360mm of the ruler for chamfering, the subsequent time is shaped according to the blank size of 360mm, the corner finish forging temperature is 925 ℃, then an end pressing clamp handle is filled, the billet is cut in the billet and then is returned to a furnace for heat preservation, and the surface temperature is 1200 ℃ for heat preservation for 2 h;
⑶ drawing out an octagon with a quick forging machine by an octagon drawing process to 280mm, wherein the first time is pressed to 280mm of a ruler, the second time is drawn out by 120mm of rolling reduction, the third time and the fourth time are pressed to 280mm of the ruler for chamfering, the subsequent times are shaped according to 280mm of blank size, the corner finish forging temperature is 930 ℃, and the billet surface temperature is 1180 ℃ and the temperature is maintained for 2h by returning to the furnace;
⑷ quick forging machine octagonal drawing and cogging to 190mm decahexagonal, wherein the first time is pressed to 190mm of a ruler, the second time is 120mm of rolling reduction drawing, the third and fourth times are pressed to 190mm of a ruler for chamfering, the subsequent time is shaped to sixteen angles according to 190mm of blank size, the corner finish forging temperature is 920 ℃, each section of steel billet in ⑵ is cut into 1550mm multiplied by 2 sections, the cutting pliers hold the temperature of the post-passing radial forging machine chamber furnace, and the surface temperature is 1160 ℃ for 2 h;
⑸ the blank is taken out of the furnace and is kept at 1150 ℃ for 10min by using a compensation furnace, the diameter forging machine adopts the general procedure of austenitic stainless steel to form the material, the finish forging temperature is 930 ℃, and the length is 5.8 m.
3. The forging method of large-specification fine-grained austenitic gas valve steel SNCrW according to claim 1, wherein a forged electroslag ingot is smelted by adopting an EAF/non-vacuum induction furnace + LF + VOD/VHD + ESR method, and the ingot is homogenized; the method is characterized in that: the forging method comprises the following steps:
⑴ upsetting operation is carried out by a quick forging machine, the upsetting amount is 350mm, a double-end forging mode is adopted, the 80mm reduction is drawn out to be an octagon of 450mm, a clamp handle is arranged at the end of a bottom pad, and the temperature is kept for 2.5h at 1200 ℃ through a furnace returning and reburning system;
⑵ quick forging machine octagonal beating process is drawn to 370mm octagonal, wherein the first time is pressed to 370mm ruler, the second time is drawn to length with 120mm rolling reduction, the third and fourth times are pressed to 370mm ruler chamfer, the subsequent passes are shaped according to 370mm billet size, the corner finish forging temperature is 925 ℃, then end pressing clamp handles are filled, the billet is cut 1/3+2/3 partially and then is returned to the furnace for heat preservation, and the surface temperature is 1200 ℃ for heat preservation for 2.5 h;
⑶ drawing out an octagonal material with a octagonal beating process of a quick forging machine to 280mm, wherein the first time is pressed to 290mm of a ruler, the second time is drawn out with 120mm of rolling reduction, the third time and the fourth time are pressed to 290mm of the ruler for chamfering, the subsequent times are shaped according to 290mm of blank size, the corner finish forging temperature is 925 ℃, the surface temperature of a billet is 1180 ℃, and the temperature is maintained for 2.5 hours after the furnace is returned;
⑷ quick forging machine is used for forging octagonal process, drawing and cogging to 200mm decahexagonal, wherein the first pass is pressed to 200mm of a ruler, the second pass is drawn to 120mm of rolling reduction, the third pass and the fourth pass are pressed to 200mm of a ruler for chamfering, the subsequent passes are shaped to sixteen angles according to 200mm of blank size, the corner finish forging temperature is 930 ℃, the billet is cut into 1700mm multiplied by 2 sections in 2/3 billet in ⑵, the cogging length of 1/3 billet is 1750mm, the billet is cut into a pair and then passes through a radial forging machine chamber furnace for heat preservation, and the surface temperature is 1160 ℃ for heat preservation for 2 h;
⑸ the blank is taken out of the furnace and is kept warm for 10min at 1145 ℃ by a compensating furnace, the radial forging machine adopts the general procedure of austenitic stainless steel to form the material, the finish forging temperature is 930 ℃, and the length is 5.9 m.
4. The forging method of large-specification fine-grained austenitic gas valve steel SNCrW according to claim 1, wherein a forged electroslag ingot is smelted by adopting an EAF/non-vacuum induction furnace + LF + VOD/VHD + ESR method, and the ingot is homogenized; the method is characterized in that: the forging method comprises the following steps:
⑴ upsetting operation is carried out by a quick forging machine, the upsetting amount is 350mm, a double-end forging mode is adopted, the 80mm reduction is drawn out to be 450mm octagonal, a clamp handle is arranged at the end of a bottom pad, and the temperature is kept for 2h at 1200 ℃ through a furnace returning and reburning system;
⑵ quick forging machine octagonal beating process is used for drawing to 380mm octagonal, wherein the first time is pressed to 380mm ruler, the second time is 120mm reduction drawing, the third and fourth times are pressed to 380mm ruler chamfering, the subsequent passes are shaped according to 380mm blank size, the corner finish forging temperature is 930 ℃, then end pressing clamp handles are filled, the steel billet 1/3+2/3 is cut off partially and then is returned to a furnace for heat preservation, and the surface temperature is 1200 ℃ for heat preservation for 2 h;
⑶ drawing out an octagonal material with a size of 310mm by a quick forging machine, wherein the octagonal material is pressed to a ruler with a size of 310mm for the first time, drawn out with a rolling reduction of 120mm for the second time, pressed to a ruler with a size of 310mm for chamfering for the third and fourth times, and shaped according to the size of 280mm of a blank in the subsequent passes, wherein the corner finish forging temperature is 925 ℃, and the surface temperature of a billet is 1180 ℃ and the temperature is kept for 2 hours by returning to the furnace;
⑷ quick forging machine octagonal process drawing and cogging to 220mm decahexagonal, wherein the first time is pressed to 220mm of a ruler, the second time is 120mm of rolling reduction drawing, the third and fourth times are pressed to 220mm of a ruler and chamfer, the subsequent time is shaped to sixteen angles according to 220mm of blank size, the corner finish forging temperature is 925 ℃, the lengths of two sections of blanks are 2050mm, the steel billet is cut by a clamp and then passes through a radial forging machine chamber furnace for heat preservation, and the surface temperature is 1160 ℃ for heat preservation for 2.5 h;
⑸ the blank is taken out of the furnace and is kept warm for 10min at 1145 ℃ by a compensating furnace, the radial forging machine adopts the general procedure of austenitic stainless steel to form the material, the finish forging temperature is 930 ℃, and the length is 5.9 m.
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