Superfine bainite frog steel forge piece and manufacturing method thereof

Abstract

The invention relates to a superfine bainite frog steel forge piece and a manufacturing method thereof.The superfine bainite steel obtains high strength, high plasticity and good toughness through bainite structure fine grain strengthening and toughening and phase change plastification effects, is advanced high-strength steel with the best application prospect and comprises, by weight, 0.30-0.40% of C, 1.40-2.00% of Si, 1.40-2.00% of Mn, 1.10-1.50% of Cr, 0.20-0.40% of Ni, 0.30-0.50% of Mo, smaller than or equal to 0.20% of V, smaller than or equal to 0.010% of S, smaller than or equal to 0.020% of P, 0.20-0.40% of Al, smaller than or equal to 0.15% of Cu, smaller than 0.01% of Ti, smaller than or equal to 0.01% of Nb and the balance Fe. The production process comprises the following steps of: melting waste steel by using an electric arc furnace, blowing argon to refine a steel ladle, deoxidizing and desulphurizing, adjusting components, hoisting the steel ladle into a vacuum tank for degassing when the temperature meets the requirements, performing die casting to form an electrode blank, performing down-conversion electroslag remelting, and performing down-conversion forging after hot charging or annealing to form a frog product. The corrosion resistance of the steel for the railway frog manufactured through the technology is more excellent than that of common frog steel.

Description

Technical Field

[0001] The invention belongs to the technical field of steelmaking and forging technology, and relates to an ultrafine bainite frog steel forging and a manufacturing method thereof. The ultrafine bainite steel utilizes the fine grain strengthening and toughening of bainite structure and the phase transformation plasticization effect to obtain high strength, high plasticity and good toughness, and is the most promising advanced high-strength steel. Background Art

[0002] Railway is a national strategic, leading and key infrastructure. The frog is an important component of the railway track structure and is a special device required for the locomotive wheels to switch from one track to another. The frog will be subjected to a huge wheel impact load when the locomotive passes. At this time, in addition to the greatly increased static load, it will also bear the maximum dynamic load on the rail. The dynamic load on the rail and the switch is 2-5 times the static load. The working conditions of the frog are extremely harsh, so the requirements for the material of the frog are very strict.

[0003] The above series of bainitic frog steels generally have the defect of short life. How to further develop bainitic steel frogs and utilize the bainitic structure fine grain strengthening and toughening and phase transformation plasticization effect to obtain bainitic steel frogs with higher strength, higher plasticity, longer life and good toughness is a task with more application prospects. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an ultrafine bainite frog steel forging and a manufacturing method thereof. The ultrafine bainite frog steel forging manufactured by the process has better corrosion resistance than ordinary frog steel.

[0005] The object of the present invention is achieved in that: An ultrafine bainite frog steel forging comprises the following chemical components in percentage by weight: C 0.30-0.40%, Si 1.40-2.00%, Mn 1.40-2.00%, Cr 1.10-1.50%, Ni 0.20-0.40%, Mo 0.30-0.50%, V≤0.20%, S≤0.010%, P≤0.020%, Al0.20-0.40%, Cu≤0.15%, Ti<0.01%, Nb≤0.01%, wherein there is no clear requirement for the contents of As, Sn, Pb, Sb and Bi, and the balance is iron.

[0006] The invention discloses an ultrafine bainite frog steel forging, wherein the following components are optimally selected in terms of weight percentage: C 0.30-0.35%, Si 1.40-1.60%, Mn 1.70-2.00%, Cr 1.10-1.30%, Ni 0.20-0.30%, Mo 0.30-0.40%, V 0.10-0.20%, S≤0.003%, P≤0.010%, Al 0.25-0.40%, Cu≤0.10%, Ti<0.01%, Nb≤0.01%, As, Sn, Pb, Sb and Bi are all ≤0.010%, and the balance is iron.

[0007] A method for manufacturing ultra-fine bainite frog steel forgings, wherein the steel manufacturing method adopts an electric arc furnace to melt scrap steel, argon blowing in a ladle for refining, deoxidation and desulfurization, adjusting the composition and temperature to meet the requirements, hanging the ladle into a vacuum tank for degassing, mold casting into an electrode blank, and then transferring to an electroslag remelting. Hot delivery Or after annealing, it is forged into frog products; the specific processes include the following: Step 1), batching: the charge is composed of 50-70% high-quality steel scraps, 10-30% pig iron or nickel-containing pig iron, and 10-30% returned steel head according to weight percentage, and the five harmful elements As, Sn, Pb, Sb, and Bi in the raw materials are controlled to be ≤0.010%; Step 2), electric arc furnace smelting: control the electric furnace steel tapping according to weight percentage [C] ≥ 0.05%, [P] ≤ 0.005%, the tapping temperature is 1640 ~ 1660 ℃, and add ferrosilicon 15.0 ~ 20.0 kg / t, ferromanganese alloy 5.0 ~ 10.0 kg / t, ferrochrome alloy 8.0 ~ 10.0 kg / t, aluminum block 3.0 ~ 5.0 kg / t, lime 3.0 ~ 5.0 kg / t with the steel flow during the tapping process; Step 3), ladle furnace refining: After the ladle furnace is in place, first connect argon gas for stirring, heating and refining, adjust the temperature ≥1550℃, add 3-5.0kg / t lime and 1-2.0kg / t fluorite according to the amount of slag, add 1-2.0kg / t calcium carbide, 1.0-2.0kg / t carbon powder, and 2.0-3.0kg / t silicon calcium powder deoxidizer after slag melting, adjust the composition after the slag is white, if the aluminum component is not within the limit, you can feed aluminum wire to adjust the composition, when feeding the wire, pay attention to the slag must be white, after feeding the aluminum wire, use silicon calcium powder 1.0-3.0kg / t in two to four batches for deoxidation and maintain a reducing atmosphere to ensure uniform composition and temperature; the adjustment of manganese composition should take into account the evaporation in the VD process, and argon is blown throughout the refining period. According to the requirements of argon stirring at different stages of refining, adjust the flow rate at any time to ensure uniform and sufficient stirring intensity; Step 4), vacuum tank degassing: temperature 1640 ~ 1670 ℃ from LF furnace hanging bag into the vacuum tank for degassing, maintain time ≥ 15 minutes at ≤ 0.67mbar, online hydrogen and oxygen determination after VD, control [H] ≤ 1.0ppm, [O] ≤ 5.0ppm, take glass tube samples to analyze nitrogen content, control [N] ≤ 50ppm; [Al] component is not within the limit, argon blowing and aluminum wire feeding are allowed to adjust; argon blowing weak stirring time before tapping ≥ 15 minutes, the hanging bag temperature is 1540 ~ 1550 ℃.

[0008] Step 5), casting: before scheduling, carefully select the casting mold, preferably the casting mold with good inner wall quality and polish and clean it, and the use temperature is ≥50℃. The flow steel bricks in the soup channel system must be dried and carefully selected before use to ensure that the pouring system is clean and dry. The calming time is ≥10 minutes. Before pouring, the mold is filled with argon and argon is used for protection. The pouring temperature is 1530-1540℃. The electrode billet is poured with insulating risers, 1-2.0kg / t carbon-free protective slag, and 0.5-1.0kg / t heating agent. After pouring, add 1-2.0kg / t carbonized rice husk to ensure the shrinkage compensation effect. After lifting the mold, the riser is hot-cut and annealed. After the electrode billet is demolded, it is hot-sent to the electric slag or annealed; the annealing insulation temperature is controlled at 700℃, and the insulation time is calculated according to the maximum cross-sectional size at 1.5 hours / 100mm; Step 6), electroslag: polish and clean the oxide scale and floating rust on the surface of the electrode blank, bake at ≥400℃ for ≥4 hours after welding; clean the scum on the inner wall of the crystallizer before use, clean the arc starting steel plate and the ingot guard plate surface with a manual polisher, add 110Kg of pre-melted slag, the pre-melted slag is prepared according to the weight ratio of Al203:CaF2=3:7, bake at ≥400℃ for 4 hours, keep warm at ≥200℃, and take it as needed; Step 7), add the slag in 2-3 batches, with an interval of 3-5 minutes between each batch to ensure that the slag is clear; after adding the slag, the furnace mouth needs to be tightly covered; after the electrical system is stable at the beginning of remelting, the power slowly decreases, not too fast, to avoid defects on the ingot surface above 400mm at the bottom; during the remelting of this product, the current fluctuation is strictly controlled to be ≤±10%; before slagging, blow argon gas downward into the crystallizer for 3-8 minutes, with a flow rate of 10-20Nm3 / h; during the remelting process, argon gas is blown downward for protection; during the remelting process, pay attention to the sealing of the furnace mouth, cover the upper mouth of the crystallizer with soft asbestos, and keep the dust removal exhaust port away from the crystallizer mouth appropriately; observe the total water inlet temperature during the remelting process, and control the water outlet temperature to 35-40℃; add 0.5kg aluminum powder to the slag, mix the aluminum powder and slag evenly, and then add it with the slag; Step 8), the average melting rate is 340-400kg / h, and the water temperature is controlled at 35-40℃; when the water temperature exceeds the required range and needs to be adjusted, the change of the water temperature shall not exceed 2℃ each time, and the water temperature shall be tested and recorded during and 4-6 minutes after the adjustment; the mold is cooled for 50-70 minutes, annealed or sent hot to the forging company for heating and forging; Step 9), forging: the first step of the precision forging machine uses a forging round hammer, and the initial forging temperature is controlled at 850-1150°C. The electroslag ingot is forged in three passes, and the deformation is Φ500mm→Φ420mm→Φ330mm→Φ250mm, and the precision forging is to Φ250 intermediate round billet, and the pulling speed is 1.5m / min-2.5m / min; the second step of the precision forging machine uses a rectangular hammer, and the Φ250 intermediate billet is first returned to the 850°C heating furnace for material, and the temperature is quickly raised to 1100-1150°C for 1.5-2.0 hours. The precision forging machine uses a rectangular hammer to precision forge to the finished product size, and finally two passes are finished. During the finishing, the penultimate pass does not leave any amount on the wide surface, and 3mm is left in the thickness direction for finishing. The last pass does not leave any amount for finishing to prevent the forging surface from being concave; in the process of forging the finished product, the pulling speed must be controlled to be not less than 5m / min for each pass to avoid bending and angular cracks; Step 10), annealing: After the finished product is forged, it is first air-cooled to 350-400℃ and then transferred to the heating furnace for 2 hours, heated to 600-650℃ at maximum power, heated for 2 hours, then heated to 900℃±10 at maximum power, average temperature time ≥2 hours, heated for 2 hours, then air-cooled to 350-400℃ and heated for 5 hours, heated to 650℃±10 at maximum power, average temperature time ≥7 hours, heated for 17 hours, then air-cooled to 350-400℃ and heated for 2 hours, then heated to 690℃ at maximum power, average temperature time ≥5.5 hours, heated for 10 hours, then cooled to 400℃ at ≤40℃ / h, then cooled to ≤300℃ at ≤15℃ / h, straightened while hot, and the forgings can be air-cooled to room temperature after straightening for inspection.

[0009] The beneficial effects of the present invention are as follows: The present invention uses high-quality steel scraps, pig iron or nickel-containing pig iron, and return steel head when mixing materials, and controls As, Sn, Pb, Sb, and Bi in the raw materials to be ≤0.010%. Ferrosilicon, ferromanganese, ferrochrome, aluminum blocks, and slag-making materials are added with the steel flow during the steel tapping process of the electric arc furnace; the ladle furnace is argon-blown for refining, heating, deoxidation, desulfurization, alloy composition adjustment, vacuum degassing, and steel tapping; and the electrode blank is mold-casted. The electrode blank is electroslag-remelted into an electroslag ingot and forged into a heart rail and an insert frog. It is ensured that the finished product has [H]≤0.8PPm, [O]≤15PPm, and [N]≤70PPm. DETAILED DESCRIPTION

[0010] Embodiment: A method for manufacturing ultra-fine bainite frog steel forgings, wherein the steel manufacturing method adopts an electric arc furnace to melt scrap steel, argon blowing in a ladle for refining, deoxidation and desulfurization, adjusting the composition and temperature to meet the requirements, hanging the ladle into a vacuum tank for degassing, mold casting into an electrode blank, and then transferring to an electroslag remelting, Hot delivery Or after annealing, it is forged into frog products; the specific processes include the following: Step 1), batching: the charge is composed of 50-70% high-quality steel scraps, 10-30% pig iron or nickel-containing pig iron, and 10-30% returned steel head according to weight percentage, and the five harmful elements As, Sn, Pb, Sb, and Bi in the raw materials are controlled to be ≤0.010%; Step 2), electric arc furnace smelting: control the electric furnace steel tapping according to weight percentage [C] ≥ 0.05%, [P] ≤ 0.005%, the tapping temperature is 1640 ~ 1660 ℃, and add ferrosilicon 15.0 ~ 20.0 kg / t, ferromanganese alloy 5.0 ~ 10.0 kg / t, ferrochrome alloy 8.0 ~ 10.0 kg / t, aluminum block 3.0 ~ 5.0 kg / t, lime 3.0 ~ 5.0 kg / t with the steel flow during the tapping process; Step 3), ladle furnace refining: After the ladle furnace is in place, first connect argon gas for stirring, heating and refining, adjust the temperature ≥1550℃, add 3-5.0kg / t lime and 1-2.0kg / t fluorite according to the amount of slag, add 1-2.0kg / t calcium carbide, 1.0-2.0kg / t carbon powder, and 2.0-3.0kg / t silicon calcium powder deoxidizer after slag melting, adjust the composition after the slag is white, if the aluminum component is not within the limit, you can feed aluminum wire to adjust the composition, when feeding the wire, pay attention to the slag must be white, after feeding the aluminum wire, use silicon calcium powder 1.0-3.0kg / t in two to four batches for deoxidation and maintain a reducing atmosphere to ensure uniform composition and temperature; the adjustment of manganese composition should take into account the evaporation in the VD process, and argon is blown throughout the refining period. According to the requirements of argon stirring at different stages of refining, adjust the flow rate at any time to ensure uniform and sufficient stirring intensity; Step 4), vacuum tank degassing: temperature 1640 ~ 1670 ℃ from LF furnace hanging bag into the vacuum tank for degassing, keep time ≥ 15 minutes at ≤ 0.67mbar, online hydrogen and oxygen determination after VD, control [H] ≤ 1.0ppm, [O] ≤ 5.0ppm, take glass tube sample to analyze nitrogen content, control [N] ≤ 50ppm; [Al] component is not within the limit, argon blowing and aluminum wire feeding are allowed to adjust; argon blowing weak stirring time before tapping ≥ 15 minutes, hanging bag temperature 1540 ~ 1550 ℃; Step 5), casting: before scheduling, carefully select the casting mold, preferably the casting mold with good inner wall quality and polish and clean it, and the use temperature is ≥50℃; the flow steel bricks in the soup channel system must be dried and carefully selected before use to ensure that the pouring system is clean and dry; the calming time is ≥10 minutes, and the mold is filled with argon and argon gas is used for pouring before pouring; the pouring temperature is 1530~1540℃. Add insulating risers, 1~2.0kg / t carbon-free protective slag, 0.5~1.0kg / t heating agent to the electrode billet pouring, and add 1~2.0kg / t carbonized rice husk after pouring to ensure the shrinkage compensation effect; hot cut risers are annealed after lifting the mold; hot electric slag is sent or annealed after the electrode billet is demolded; the annealing insulation temperature is controlled at 700℃, and the insulation time is calculated according to the maximum cross-sectional size at 1.5 hours / 100mm; Step 6), electroslag: polish and clean the oxide scale and floating rust on the surface of the electrode blank, and bake at ≥400℃ for ≥4 hours after welding; clean the slag on the inner wall of the crystallizer before use, and use a manual polisher to clean the surface of the arc starting steel plate and the ingot guard plate; use a pre-melted slag with a weight ratio of 3:7, bake at ≥400℃ for 4 hours, keep warm at ≥200℃, and take it out as needed; Step 7), add the slag in 2-3 batches, with an interval of 3-5 minutes between each batch to ensure that the slag is clear; after adding the slag, the furnace mouth needs to be tightly covered; after the electrical system is stable at the initial stage of remelting, the power slowly decreases, not too fast, to avoid defects on the ingot surface above 400mm at the bottom; during the remelting of this product, the current fluctuation is strictly controlled to be ≤±10%; before slagging, blow argon gas downward into the crystallizer for 3-8 minutes, with a flow rate of 10-20Nm3 / h; during the remelting process, argon gas is blown downward for protection; during the remelting process, pay attention to the sealing of the furnace mouth, cover the upper mouth of the crystallizer with soft asbestos, and keep the dust removal exhaust port away from the crystallizer mouth appropriately; observe the total water inlet temperature during the remelting process, and control the water outlet temperature to 35-40℃; add 0.5kg aluminum powder to the slag, mix the Al powder and slag evenly, and then add it with the slag; Step 8), average melting rate 340 ~ 400kg / h, water temperature controlled at 35-40 ℃. When the water temperature exceeds the required range and needs to be adjusted, each adjustment should not exceed 2 ℃ change, and the water temperature should be tested and recorded during and 4-6 minutes after adjustment; mold cooling for 50-70 minutes, annealing or hot delivery to the forging company for heating and forging.

[0011] Step 9), forging: the first step of the precision forging machine uses a forging round hammer, and the initial forging temperature is controlled at 850-1150°C. The electroslag ingot is forged in three passes, and the deformation is Φ500mm→Φ420mm→Φ330mm→Φ250mm, and the precision forging is to Φ250 intermediate round billet, and the pulling speed is 1.5m / min-2.5m / min; the second step of the precision forging machine uses a rectangular hammer, and the Φ250 intermediate billet is first returned to the 850°C heating furnace for material, and the temperature is quickly raised to 1100-1150°C for 1.5-2.0 hours. The precision forging machine uses a rectangular hammer to precision forge to the finished product size, and finally two passes are finished. During the finishing, the penultimate pass does not leave any amount on the wide surface, and 3mm is left in the thickness direction for finishing. The last pass does not leave any amount for finishing to prevent the forging surface from being concave; in the process of forging the finished product, the pulling speed must be controlled to be not less than 5m / min for each pass to avoid bending and angular cracks; Step 10), annealing: After the finished product is forged, it is first air-cooled to 350-400℃ and then transferred to the heating furnace for 2 hours, heated to 600-650℃ at maximum power, heated for 2 hours, then heated to 900℃±10 at maximum power, average temperature time ≥2 hours, heated for 2 hours, then air-cooled to 350-400℃ and heated for 5 hours, heated to 650℃±10 at maximum power, average temperature time ≥7 hours, heated for 17 hours, then air-cooled to 350-400℃ and heated for 2 hours, then heated to 690℃ at maximum power, average temperature time ≥5.5 hours, heated for 10 hours, then cooled to 400℃ at ≤40℃ / h, then cooled to ≤300℃ at ≤15℃ / h, straightened while hot, and the forgings can be air-cooled to room temperature after straightening for inspection.

[0012] The chemical composition of the ultrafine bainite frog steel forged by electroslag ingot is shown in Table 1, and the gas is shown in Table 2; the test results show that the composition and gas content of the ultrafine bainite frog steel produced by the process of the present invention meet the requirements, and the ultrafine bainite frog steel forgings made therefrom have better corrosion resistance than ordinary frog steel.

[0013] Appendix: The chemical composition of ultrafine bainite frog steel is as follows Table 1 Table 1 Chemical composition (m%) element Target ingredients This embodiment C 0.30-0.40 0.28 Si 1.40-2.00 1.50 Mn 1.40-2.00 1.70 P ≤0.020 0.010 S ≤0.010 0.003 Cr 1.10-1.50 1.30 Mo 0.30-0.50 0.40 Ni 0.20-0.40 0.30 V ≤0.20 0.11 Al 0.20-0.40 0.35 As ≤0.010 0.007 Sn ≤0.010 0.005 Pb ≤0.010 0.001 Sb ≤0.010 0.002 Bi ≤0.010 0.001 Appendix: Low-cost frog steel gas is as follows Table 2 Table 2 Gas (ppm) element Target This embodiment [H] ≤0.8 0.56 [O] ≤15 9.0 [N] ≤70 62 .

Claims

1. An ultrafine bainite frog steel forging, characterized in that: The chemical components include the following in weight percentage: C 0.30-0.40%, Si 1.40-2.00%, Mn 1.40-2.00%, Cr 1.10-1.50%, Ni 0.20-0.40%, Mo0.30-0.50%, V≤0.20%, S≤0.010%, P≤0.020%, Al0.20-0.40%, Cu≤0.15%, Ti<0.01%, Nb≤0.01%, among which there is no clear requirement for the content of As, Sn, Pb, Sb and Bi, and the balance is iron.

2. An ultrafine bainite frog steel forging, characterized in that: The following components are the best choices in weight percentage: C 0.30-0.35%, Si 1.40-1.60%, Mn 1.70-2.00%, Cr 1.10-1.30%, Ni 0.20-0.30%, Mo 0.30-0.40%, V 0.10-0.20%, S≤0.003%, P≤0.010%, Al 0.25-0.40%, Cu≤0.10%, Ti<0.01%, Nb≤0.01%, As, Sn, Pb, Sb, Bi are all ≤0.010%, and the balance is iron.

3. A method for manufacturing an ultrafine bainite frog steel forging according to claim 1 or 2, characterized in that: The steel manufacturing method adopts an electric arc furnace to melt scrap steel, argon blowing in a ladle for refining, deoxidation and desulfurization, adjusting the composition and temperature to meet the requirements, hanging the ladle into a vacuum tank for degassing, molding into an electrode blank, and then transferring to an electroslag for remelting. Hot delivery Or after annealing, it is forged into frog products; the specific processes include the following: Step 1), batching: the charge is composed of 50-70% high-quality steel scraps, 10-30% pig iron or nickel-containing pig iron, and 10-30% returned steel head according to weight percentage, and the five harmful elements As, Sn, Pb, Sb, and Bi in the raw materials are controlled to be ≤0.010%; Step 2), electric arc furnace smelting: control the electric furnace steel tapping according to weight percentage [C] ≥ 0.05%, [P] ≤ 0.005%, the tapping temperature is 1640 ~ 1660 ℃, and add ferrosilicon 15.0 ~ 20.0 kg / t, ferromanganese alloy 5.0 ~ 10.0 kg / t, ferrochrome alloy 8.0 ~ 10.0 kg / t, aluminum block 3.0 ~ 5.0 kg / t, lime 3.0 ~ 5.0 kg / t with the steel flow during the tapping process; Step 3), ladle furnace refining: After the ladle furnace is in place, first connect argon gas for stirring, heating and refining, adjust the temperature ≥1550℃, add 3-5.0kg / t lime and 1-2.0kg / t fluorite according to the amount of slag, add 1-2.0kg / t calcium carbide, 1.0-2.0kg / t carbon powder, and 2.0-3.0kg / t silicon calcium powder deoxidizer after slag melting, adjust the composition after the slag is white, if the aluminum component is not within the limit, you can feed aluminum wire to adjust the composition, when feeding the wire, pay attention to the slag must be white, after feeding the aluminum wire, use silicon calcium powder 1.0-3.0kg / t in two to four batches for deoxidation and maintain a reducing atmosphere to ensure uniform composition and temperature; the adjustment of manganese composition should take into account the evaporation in the VD process, and argon is blown throughout the refining period. According to the requirements of argon stirring at different stages of refining, adjust the flow rate at any time to ensure uniform and sufficient stirring intensity; Step 4), vacuum tank degassing: temperature 1640 ~ 1670 ℃ from LF furnace hanging bag into the vacuum tank for degassing, keep time ≥ 15 minutes at ≤ 0.67mbar, online hydrogen and oxygen determination after VD, control [H] ≤ 1.0ppm, [O] ≤ 5.0ppm, take glass tube sample to analyze nitrogen content, control [N] ≤ 50ppm; [Al] component is not within the limit, argon blowing and aluminum wire feeding are allowed to adjust; argon blowing weak stirring time before tapping ≥ 15 minutes, hanging bag temperature 1540 ~ 1550 ℃; Step 5), casting: before production scheduling, carefully select the casting mold, preferably the casting mold with good inner wall quality and polish and clean it, and the use temperature is ≥50℃; the flow steel bricks of the soup channel system should be dried and carefully selected before use to ensure that the pouring system is clean and dry; the calming time is ≥10 minutes, and the mold is filled with argon and argon protection is used for pouring before pouring; the pouring temperature is 1530-1540℃, and the electrode blank is poured with an insulating riser, 1-2.0kg / t carbon-free protective slag, and 0.5-1.0kg / t heating agent. After pouring, 1-2.0kg / t carbonized rice husk is added to ensure the shrinkage compensation effect. After lifting the mold, the riser is hot-cut and annealed. After the electrode blank is demolded, hot electric slag is sent or annealed; the annealing and insulation temperature is controlled at 700℃, and the insulation time is calculated according to the maximum cross-sectional size at 1.5 hours / 100mm; Step 6), electroslag: polish and clean the oxide scale and floating rust on the surface of the electrode blank, bake at ≥400℃ for ≥4 hours after welding; clean the scum on the inner wall of the crystallizer before use, clean the arc starting steel plate and the ingot guard plate surface with a manual polisher, add 110Kg of pre-melted slag, the pre-melted slag is prepared according to the weight ratio of Al203:CaF2=3:7, bake at ≥400℃ for 4 hours, keep warm at ≥200℃, and take it as needed; Step 7), add the slag in 2-3 batches, with an interval of 3-5 minutes between each batch to ensure that the slag is clear; after adding the slag, the furnace mouth needs to be tightly covered; after the electrical system is stable at the beginning of remelting, the power slowly decreases, not too fast, to avoid defects on the ingot surface above 400mm at the bottom; during the remelting of this product, the current fluctuation is strictly controlled to be ≤±10%; before slagging, blow argon gas downward into the crystallizer for 3-8 minutes, with a flow rate of 10-20Nm3 / h; during the remelting process, argon gas is blown downward for protection; during the remelting process, pay attention to the sealing of the furnace mouth, cover the upper mouth of the crystallizer with soft asbestos, and keep the dust removal exhaust port away from the crystallizer mouth appropriately; observe the total water inlet temperature during the remelting process, and control the water outlet temperature to 35-40℃; add 0.5kg aluminum powder to the slag, mix the aluminum powder and slag evenly, and then add it with the slag; Step 8), the average melting rate is 340-400kg / h, and the water temperature is controlled at 35-40℃; when the water temperature exceeds the required range and needs to be adjusted, the change of the water temperature shall not exceed 2℃ each time, and the water temperature shall be tested and recorded during and 4-6 minutes after the adjustment; the mold is cooled for 50-70 minutes, annealed or sent hot to the forging company for heating and forging; Step 9), forging: the first step of the precision forging machine uses a forging round hammer, and the initial forging temperature is controlled at 850-1150°C. The electroslag ingot is forged in three passes, and the deformation is Φ500mm→Φ420mm→Φ330mm→Φ250mm, and the precision forging is to Φ250 intermediate round billet, and the pulling speed is 1.5m / min-2.5m / min; the second step of the precision forging machine uses a rectangular hammer, and the Φ250 intermediate billet is first returned to the 850°C heating furnace for material, and the temperature is quickly raised to 1100-1150°C for 1.5-2.0 hours. The precision forging machine uses a rectangular hammer to precision forge to the finished product size, and finally two passes are finished. During the finishing, the penultimate pass does not leave any amount on the wide surface, and 3mm is left in the thickness direction for finishing. The last pass does not leave any amount for finishing to prevent the forging surface from being concave; in the process of forging the finished product, the pulling speed must be controlled to be not less than 5m / min for each pass to avoid bending and angular cracks; Step 10), annealing: After the finished product is forged, it is first air-cooled to 350-400℃ and then transferred to the heating furnace for 2 hours, heated to 600-650℃ at maximum power, heated for 2 hours, then heated to 900℃±10 at maximum power, average temperature time ≥2 hours, heated for 2 hours, then air-cooled to 350-400℃ and heated for 5 hours, heated to 650℃±10 at maximum power, average temperature time ≥7 hours, heated for 17 hours, then air-cooled to 350-400℃ and heated for 2 hours, then heated to 690℃ at maximum power, average temperature time ≥5.5 hours, heated for 10 hours, then cooled to 400℃ at ≤40℃ / h, then cooled to ≤300℃ at ≤15℃ / h, straightened while hot, and the forgings can be air-cooled to room temperature after straightening for inspection.