Preparation method of low-segregation high-carbon stainless steel billet

Abstract

The invention relates to the field of metallurgy, and discloses a preparation method of a low-segregation high-carbon stainless steel billet, which comprises the following steps: sequentially carrying out electric furnace smelting, LF furnace refining, VD furnace refining and pouring to obtain an electrode bar; carrying out electroslag remelting on the electrode bar to obtain a steel ingot; the steel ingot is subjected to annealing treatment, and a low-segregation high-carbon stainless steel blank is obtained; wherein electroslag remelting comprises a preparation stage, an arcing stage, a steady-state remelting stage and a filling stage; in the steady-state remelting stage, the melting speed is controlled according to the weight of the steel ingot to be prepared, and it is ensured that the melting speed is stable; wherein when the weight of the steel ingot to be prepared is 2.5-3.5 tons, the melting speed is controlled to be 4.5-5.5 kg / min; when the weight of the steel ingot to be prepared is 4.5-5.5 tons, the melting speed is controlled to be 6-7 kg / min; and when the weight of the steel ingot to be prepared is 6.5-7.5 tons, the melting speed is controlled to be 7-8 kg / min. Element segregation can be controlled, the shrinkage cavity depth is reduced, and the steel billet surface quality is improved.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a method for preparing a low-segregation high-carbon stainless steel billet. Background Art

[0002] High carbon stainless steel has the characteristics of high hardness, high wear resistance and corrosion resistance, and is widely used in bearings, piston rings, etc. However, the high content of elements such as C and Cr in this series of steels can easily lead to element segregation, affecting the processing and service life of parts.

[0003] Based on this, the existing technology still needs to be improved. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for preparing a low-segregation high-carbon stainless steel billet, so as to at least solve the problem of element segregation in the high-carbon stainless steel billet.

[0005] According to one aspect of the present invention, a method for preparing a low-segregation high-carbon stainless steel billet is provided, comprising: The electrode rod is obtained by sequentially performing electric furnace smelting, LF furnace refining, VD furnace refining and casting; Electroslag remelting is performed on the electrode rod to obtain a steel ingot; The steel ingot is annealed to obtain a low-segregation high-carbon stainless steel billet; Among them, the electroslag remelting includes a preparation stage, an arc starting stage, a steady-state remelting stage and a filling stage; in the steady-state remelting stage, the melting rate is controlled according to the weight of the steel ingot to be prepared and the melting rate is ensured to be stable; when the weight of the steel ingot to be prepared is 2.5~3.5 tons, the melting rate is controlled to be 4.5~5.5kg / min; when the weight of the steel ingot to be prepared is 4.5~5.5 tons, the melting rate is controlled to be 6~7kg / min; when the weight of the steel ingot to be prepared is 6.5~7.5 tons, the melting rate is controlled to be 7~8kg / min.

[0006] According to one embodiment of the present invention, in the steady-state remelting stage, the outlet water temperature of the crystallizer is controlled to be 30-45° C., and the outlet water temperature of the crystallizer and the flow rate of the protective gas are ensured to be stable.

[0007] According to one embodiment of the present invention, during the arc starting stage, a protective gas is introduced into the electroslag furnace until the oxygen content in the furnace is reduced to below 5000 ppm, and then the electric arc is started; In the arc starting stage, the control current is 7000~13000A and the control voltage is 30~45V; In the arc starting stage, if the instantaneous current is lower than the corresponding threshold, the slag adding speed is reduced, and if the instantaneous current is higher than the corresponding threshold, the slag adding speed is increased.

[0008] According to one embodiment of the present invention, during the filling stage, the power or melting speed is gradually reduced, the filling time is ≥45 minutes, and the furnace cooling time is 50-90 minutes.

[0009] According to one embodiment of the present invention, during electroslag remelting, the slag material used contains 65-75% CaF by weight. 2 and 25~35% Al 2 O 3 The slag usage is 22~30kg / ton of steel; 25~35% of the slag is added in the preparation stage, and the remaining slag is added in the arc starting stage.

[0010] According to one embodiment of the present invention, before electroslag remelting, the method further includes: baking and heating the electrode rod, the baking heating temperature is 820-860°C, the heating rate is ≤60°C / h, and the baking heating time is 6-8h.

[0011] According to one embodiment of the present invention, argon is blown into the pouring pipe for 15 to 30 minutes within 35 minutes before pouring, the argon pressure is controlled to be 0.20 to 0.50 MPa during the pouring process, the height between the ladle water inlet and the center pouring pipe gate is controlled to be ≤150 mm, the amount of protective slag is 1.5 to 2.5 kg / t, the ingot body pouring time is 420 to 600 seconds, and the riser pouring time is 240 to 300 seconds.

[0012] According to one embodiment of the present invention, during the VD furnace refining process, the argon blowing flow rate is maintained at ≥120L / min for 15-20min, the argon blowing flow rate is reduced before breaking the vacuum, the lid is closed and stirred for 5-10min after breaking the vacuum, the static argon blowing is ≥15min, and the bag temperature is 1490-1500℃.

[0013] According to one embodiment of the present invention, during the annealing process, the heating rate is 30~50℃ / h, the heating temperature is 840~860℃, the holding time is 13~15h, and after the holding is completed, it is slowly cooled to ≤400℃ at a cooling rate of ≤20℃ / h before being taken out of the furnace.

[0014] According to one embodiment of the present invention, the carbon content of the low segregation high carbon stainless steel billet is greater than 0.5%, the carbon segregation index is 1.5-2.0, the center porosity level is 0, the center shrinkage level is 0, and the center segregation level is 0.

[0015] In the technical solution of the present invention, by controlling the melting rate in the steady-state remelting stage during the electroslag remelting process and combining the setting of relevant parameters in each step, the element segregation can be effectively controlled, and the shrinkage cavity depth can be reduced, the surface quality of the steel billet can be improved, and the yield rate can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A flow chart showing a method for preparing a low-segregation high-carbon stainless steel billet according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0018] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0019] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0020] refer to Figure 1 The present invention provides a method for preparing a low-segregation high-carbon stainless steel billet, comprising: The electrode rod is obtained by sequentially performing electric furnace smelting, LF furnace refining, VD furnace refining and casting; Electroslag remelting is performed on the electrode rod to obtain a steel ingot; wherein the electroslag remelting includes a preparation stage, an arc starting stage, a steady-state remelting stage and a filling stage; The steel ingot is annealed to obtain a low-segregation high-carbon stainless steel billet.

[0021] In an embodiment of the present invention, the carbon content of the high carbon stainless steel billet may be greater than 0.5%, for example, greater than 0.6%, greater than 0.7%, greater than 0.8%, or greater than 0.9%. In a specific embodiment, the high carbon stainless steel is 95Cr18 stainless steel, and its composition includes by mass percentage: C: 0.90-1.00%; Si: ≤0.80%; Mn: ≤0.80%; S: ≤0.030%; P: ≤0.035%; Cr: 17.00-19.00%; Ni: ≤0.60%; Mo: ≤0.75%.

[0022] In the embodiment of the present invention, by setting the relevant parameters of each step including the electroslag remelting step, under the synergistic effect of multiple parameters of multiple steps, the element segregation can be effectively controlled, and the shrinkage cavity depth can be reduced, the surface quality of the steel billet can be improved, and the yield rate can be increased. The inventors of the present application recognize that in the process of pouring the electrode rod, the use of a lower pouring temperature and a high cooling intensity can improve the element segregation, but the high cooling intensity (short solidification time) will cause a deeper shrinkage cavity and reduce the yield rate. Therefore, the present application can control the segregation and ensure a shallower shrinkage cavity depth by matching a reasonable pouring temperature (the pouring temperature is determined by the hanging bag temperature) and pouring time, and provide a high-quality electrode rod for the electroslag remelting process. The inventors of the present application also recognize that in the electroslag remelting process, the melting rate in the steady-state remelting stage and the filling stage (the filling stage is controlled by time) directly affects the segregation and surface quality of the ingot. Generally, the molten pool depth is shallower at a lower melting rate, which can improve the element segregation, but will cause the surface quality to deteriorate. Therefore, the present application can effectively control element segregation and ensure good surface quality by matching reasonable parameters in the steady-state remelting stage and the filling stage.

[0023] Each step is described below.

[0024] Electric furnace smelting: Lime is placed on the bottom of the furnace before charging, and then pure iron and alloy raw materials are charged into the furnace according to the composition ratio of the target steel (such as 95Cr18 stainless steel); after the charge is fully melted, oxygen is blown to remove carbon, gas and inclusions at a temperature ≥1600℃, and the carbon content is reasonably controlled; lime, fluorite, CaSi, Al blocks and carbon powder are added for reduction for ≥10 minutes, and nitrogen is blown for stirring, and the steel-out temperature is ≥1650℃.

[0025] LF furnace refining: The molten steel obtained after electric furnace smelting is sent to the LF furnace and sent for electric refining for reduction. The whole process is reduced with steel slag and baked carbon powder to make the chemical composition close to the target value. When the temperature is ≥1580℃, Al is fed to the Al content of 0.06~0.08%, and the bag is hung.

[0026] VD furnace refining: The argon blowing flow rate is ≥120L / min and the holding time is 15~20min. Before breaking the vacuum, the argon blowing flow rate is adjusted to a small value. If the Al content is ≤0.005% after breaking the vacuum, feed Al wire until the Al content is 0.04%, then close the lid and stir for 5~10min. The amount of rare earth added is 10~15kg / furnace, the static argon blowing time is ≥15min, and the bag temperature is 1490~1500℃.

[0027] Pouring: ensure that the pouring pipe is purged with argon for 15-30 minutes within 35 minutes before pouring, and use argon protection for pouring with a slit nozzle. During the pouring process, the argon pressure is controlled to be 0.20-0.50 MPa. Control the ladle water inlet and the center pouring pipe gate to be accurately aligned, and control the height between the ladle water inlet and the center pouring pipe gate to be ≤150mm. When pouring the ingot body and the cap mouth, control the liquid level to rise steadily. The amount of mold casting protective slag is 1.5-2.5 kg / t, the ingot body pouring time is 420-600 s, the riser pouring time is 240-300 s, and the electrode rod is cast.

[0028] Electroslag remelting: ① Electrode rod processing The high-carbon stainless steel electrode rod is subjected to surface peeling treatment to ensure that there is no black skin or cracks on the surface, and the weld nodules and weld scars on the end face and surface of the electrode rod are cleaned. The electrode rod is baked and heated at a temperature of 820~860℃, a heating rate of ≤60℃ / h, and a baking heating time of 6~8h.

[0029] ② Slag preparation The slag used contains 65-75% CaF by weight. 2 and 25~35% Al 2 O 3 (For example, using 70% CaF 2 +30%Al 2 O 3 Pre-melted slag), the slag usage is 22~30kg / ton steel. After the pre-melted slag is unpacked, it should be added into the electroslag furnace through the slag adding port of the protective atmosphere electroslag furnace within 15 minutes to prevent the slag from absorbing water in the air.

[0030] ③Electroslag remelting (using protective atmosphere electroslag furnace for remelting) In the preparation stage, a 10-15 mm thick ingot plate of this steel grade is placed on a water-cooled base below the crystallizer, and the diameter of the ingot plate is slightly smaller than the inner diameter of the crystallizer. Then 25-35 wt% (for example, 30 wt%) of slag is added to the crystallizer through the slag feeding port. Subsequently, the electrode rod is controlled to descend to a position close to the ingot plate.

[0031] In the arc starting stage, the control mode of the electric slag furnace is current and voltage control, in which the control current is 7000~13000A and the control voltage is 30~45V. First, the protective gas is introduced into the furnace through the protective gas control valve until the oxygen content in the furnace drops below 5000ppm, and then the electric arc is started. In the process of arc starting, depending on the current and voltage fluctuations, the remaining slag is added to the furnace through the slag adding port. If the instantaneous current is lower than the corresponding threshold, the slag addition speed is reduced, and if the instantaneous current is higher than the corresponding threshold, the slag addition speed is increased. When the current and voltage are stable, it means that the slag pool in the furnace has been formed, and the arc starting stage is over. At this stage, all the slag needs to be added.

[0032] In the steady-state remelting stage, the control mode of the electroslag furnace is melting rate control, which controls the melting rate according to the weight of the steel ingot to be prepared and ensures that the melting rate is stable without drastic fluctuations; when the weight of the steel ingot to be prepared is 2.5-3.5 tons, the melting rate is controlled to be 4.5-5.5 kg / min; when the weight of the steel ingot to be prepared is 4.5-5.5 tons, the melting rate is controlled to be 6-7 kg / min; when the weight of the steel ingot to be prepared is 6.5-7.5 tons, the melting rate is controlled to be 7-8 kg / min. In addition, the crystallizer outlet water temperature is controlled to be 30-45°C, and the crystallizer outlet water temperature and protective gas flow rate are ensured to be stable without drastic fluctuations.

[0033] During the filling stage, power or melting rate reduction control is adopted to gradually reduce the power or melting rate. The filling time is ≥45min and the furnace cooling time is 50~90min.

[0034] Ingot annealing: heating rate is 30 ~50℃ / h, heating temperature is 840~860℃, holding time is 13~15h. After the holding period, slowly cool to ≤400℃ at a cooling rate of ≤20℃ / h before taking out of the furnace.

[0035] In some embodiments, the carbon segregation index of the low-segregation high-carbon stainless steel billet prepared by the above method of the present invention is 1.5-2.0, the center porosity level is level 0, the center shrinkage level is level 0, and the center segregation level is level 0. The prepared billet has high purity, effectively improved segregation, shallow molten pool depth, and good surface quality.

[0036] The following is a description based on specific embodiments.

[0037] Example 1 The low segregation high carbon stainless steel billet is prepared by the following steps: 1. Preparation of electrode rod ① Before charging, lime is placed on the bottom of the furnace, and then pure iron and alloy raw materials are charged into the furnace according to the composition ratio of 95Cr18; after the charge is fully melted, oxygen is blown at a temperature of 1610℃ to remove carbon, degas and remove inclusions, and the carbon content is reasonably controlled; lime, fluorite, CaSi, Al blocks and carbon powder are added for reduction for 15 minutes, and nitrogen is blown for stirring, and the steel-out temperature is 1658℃.

[0038] ② Enter the LF furnace and send it for electric refining for reduction. The whole process is reduced with steel slag and baked carbon powder to make the chemical composition close to the target value. When the temperature is 1590℃, feed Al to 0.06% and hang the bag.

[0039] ③VD furnace refining: The argon blowing flow rate is 130L / min and maintained for 18 minutes. Before breaking the vacuum, the argon blowing flow rate is adjusted to a small value. Feed Al wire until the Al content is 0.04%, then cover and stir for 8 minutes. The amount of rare earth added is 12kg / furnace, the static argon blowing time is 18 minutes, and the bag temperature is 1493℃.

[0040] ④ Blow argon in the pouring pipe for 20 minutes within 35 minutes before pouring, use argon protection pouring with a slit nozzle, and control the argon pressure during the pouring process at 0.3MPa. The ladle nozzle and the center pouring pipe gate are accurately aligned, and the height between the nozzle and the gate is controlled at 145mm. When pouring the ingot body and cap mouth, control the liquid level to rise steadily. The amount of mold casting protective slag is 2.0kg / t, the ingot body pouring time is 450s, the riser pouring time is 280s, and the electrode rod is cast.

[0041] 2. Electroslag Remelting ① Electrode rod processing The high-carbon stainless steel electrode rod is subjected to surface peeling treatment to ensure that there is no black skin or cracks on the surface, and the weld nodules and weld scars on the end face and surface of the electrode rod must be cleaned. The electrode rod is baked and heated at a temperature of 830°C, a heating rate of 55°C / h, and a baking time of 6h.

[0042] ② Slag preparation Using 70% CaF 2 +30%Al 2 O 3 Pre-melted slag, the amount of slag used is 25kg / ton of steel. The pre-melted slag should be added to the electroslag furnace through the slag adding port of the protective atmosphere electroslag furnace within 10 minutes after the bag is unpacked to prevent the slag from absorbing water in the air.

[0043] ③Electroslag remelting Remelting is carried out in a protective atmosphere electroslag furnace. In the preparation stage, a 12mm thick ingot plate of this steel grade is placed on a water-cooled base under the crystallizer, and the diameter of the ingot plate is slightly smaller than the inner diameter of the crystallizer. Then 30% of the slag is added to the crystallizer through the slag feeding port. Subsequently, the electrode rod is controlled to descend to a position close to the ingot plate. In the arc starting stage, the control mode of the electroslag furnace is current and voltage control, the control current is 8000A, and the control voltage is 40V. First, the protective gas is passed into the furnace through the protective gas control valve until the oxygen content in the furnace is reduced to below 5000ppm, and then the electric arc is sent. In the process of arc starting, the remaining 70% of the slag is added to the furnace through the slag feeding port. When the current and voltage are stable, it means that the slag pool in the furnace has been formed and the arc starting stage is over. In the steady-state remelting stage, the control mode of the electroslag furnace is melting rate control. The steel ingot to be prepared is a 3-ton ingot, and the corresponding melting rate is controlled at 4.5kg / min to ensure that the melting rate is stable without drastic fluctuations. And the gas flow is kept stable without drastic fluctuations. In the steady-state stage, the outlet water temperature of the crystallizer is controlled at 35°C to ensure stability without drastic fluctuations. In the filling stage, power or melting rate reduction control is adopted to gradually reduce the power or melting rate. The filling time is 50 minutes and the furnace cooling time is 60 minutes.

[0044] 3. Ingot annealing The heating rate is 40℃ / h, the heating temperature is 840℃, the holding time is 13h, and after the holding time, it is slowly cooled to 400℃ at a cooling rate of 15℃ / h and then taken out of the furnace.

[0045] The obtained low-segregation high-carbon stainless steel billet has high purity, the segregation is effectively improved, the carbon segregation index K is about 1.5, the center porosity is level 0, the center shrinkage is level 0, the center segregation is level 0, the molten pool depth is shallow, and the surface quality is good.

[0046] Example 2 The low segregation high carbon stainless steel billet is prepared by the following steps: 1. Preparation of electrode rod ① Before charging, lime is placed on the bottom of the furnace, and then pure iron and alloy raw materials are charged into the furnace according to the composition ratio of 95Cr18; after the charge is fully melted, oxygen is blown at a temperature of 1608℃ to remove carbon, degas and remove inclusions, and the carbon content is reasonably controlled; lime, fluorite, CaSi, Al blocks and carbon powder are added for reduction for 15 minutes, and nitrogen is blown for stirring, and the steel-out temperature is 1655℃.

[0047] ② Enter the LF furnace and send it for electric refining for reduction. The whole process is reduced with steel slag and baked carbon powder to make the chemical composition close to the target value. When the temperature is 1586℃, feed Al to 0.08% and hang the bag.

[0048] ③VD furnace refining: The argon blowing flow rate of 125L / min is maintained for 19 minutes. Before breaking the vacuum, the argon blowing flow rate is adjusted to a small value. Feed Al wire until the Al content reaches 0.04%, then cover and stir for 6 minutes. The amount of rare earth added is 15kg / furnace, the static argon blowing time is 20 minutes, and the bag temperature is 1499℃.

[0049] ④ Within 35 minutes before pouring, the pouring pipe was blown with argon for 22 minutes, and a slit-type nozzle was used for argon protection pouring. The argon pressure during the pouring process was controlled at 0.4MPa. The ladle nozzle and the center pouring pipe gate were accurately aligned, and the height between the nozzle and the gate was controlled at 148mm. The liquid level was controlled to rise steadily during the pouring of the ingot body and the cap. The amount of mold casting protective slag was 1.8kg / t, the ingot body pouring time was 580s, the riser pouring time was 245s, and the electrode rod was cast.

[0050] 2. Electroslag Remelting ① Electrode rod processing The high-carbon stainless steel electrode rod is subjected to surface peeling treatment to ensure that there is no black skin or cracks on the surface, and the weld nodules and weld scars on the end face and surface of the electrode rod are cleaned. The electrode rod is baked and heated at a baking temperature of 855°C, a heating rate of 60°C / h, and a baking time of 7.5h.

[0051] ② Slag preparation Using 70% CaF 2 +30%Al 2 O 3 Pre-melted slag, the slag usage is 28kg / ton of steel. After the pre-melted slag is unpacked, it should be added into the electroslag furnace through the slag adding port of the protective atmosphere electroslag furnace within 12 minutes to prevent the slag from absorbing water in the air.

[0052] ③Electroslag remelting The remelting is carried out in a protective atmosphere electroslag furnace. In the preparation stage, a 15mm thick ingot plate of this steel grade is placed on a water-cooled base under the crystallizer, and the diameter of the ingot plate is slightly smaller than the inner diameter of the crystallizer. Then 30% of the slag is added to the crystallizer through the slag feeding port. Subsequently, the electrode rod is controlled to descend to a position close to the ingot plate. In the arc starting stage, the control mode of the electroslag furnace is current and voltage control, the control current is 9000A, and the control voltage is 38V. First, the protective gas is passed into the furnace through the protective gas control valve until the oxygen content in the furnace is reduced to below 5000ppm, and then the electric arc is sent. In the process of arc starting, depending on the current and voltage fluctuations, the remaining 70% of the slag is added to the furnace through the slag feeding port. When the current and voltage are stable, it means that the slag pool in the furnace has been formed and the arc starting stage is over. In the steady-state remelting stage, the control mode of the electroslag furnace is melting rate control. The weight of the steel ingot to be prepared is 5 tons, and the corresponding ingot melting rate is controlled at 6.5kg / min to ensure that the melting rate is stable without drastic fluctuations. And maintain the protective gas flow stable without drastic fluctuations. In the steady-state stage, the crystallizer outlet water temperature is controlled at 38°C to ensure stability without drastic fluctuations. In the filling stage, power or melting speed reduction control is adopted to gradually reduce the power or melting speed, the filling time is 70 minutes, and the furnace cooling time is 80 minutes.

[0053] 3. Ingot annealing The heating rate is 50℃ / h, the heating temperature is 860℃, the holding time is 15h, and after the holding time, it is slowly cooled to 380℃ at a cooling rate of 15℃ / h before being taken out of the furnace.

[0054] The low-segregation high-carbon stainless steel billet produced has high purity, the segregation is effectively improved, the carbon segregation index K is about 1.6, the center porosity is level 0, the center shrinkage is level 0, the center segregation is level 0, the molten pool depth is shallow, and the surface quality is good.

[0055] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A method for preparing a low-segregation high-carbon stainless steel billet, characterized in that: include: The electrode rod is obtained by sequentially performing electric furnace smelting, LF furnace refining, VD furnace refining and casting; Performing electroslag remelting on the electrode rod to obtain a steel ingot; Annealing the steel ingot to obtain the low-segregation high-carbon stainless steel billet; Among them, the electroslag remelting includes a preparation stage, an arc starting stage, a steady-state remelting stage and a filling stage; in the steady-state remelting stage, the melting rate is controlled according to the weight of the steel ingot to be prepared and the melting rate is ensured to be stable; when the weight of the steel ingot to be prepared is 2.5~3.5 tons, the melting rate is controlled to be 4.5~5.5kg / min; when the weight of the steel ingot to be prepared is 4.5~5.5 tons, the melting rate is controlled to be 6~7kg / min; when the weight of the steel ingot to be prepared is 6.5~7.5 tons, the melting rate is controlled to be 7~8kg / min.

2. The method according to claim 1, characterized in that In the steady-state remelting stage, the outlet water temperature of the crystallizer is controlled to be 30-45° C., and the outlet water temperature of the crystallizer and the flow rate of the protective gas are ensured to be stable.

3. The method according to claim 1, characterized in that In the arc starting stage, a protective gas is introduced into the electroslag furnace until the oxygen content in the furnace drops below 5000 ppm, and then the electric arc is started; In the arc starting stage, the control current is 7000~13000A, and the control voltage is 30~45V; In the arc starting stage, if the instantaneous current is lower than the corresponding threshold, the slag adding speed is reduced, and if the instantaneous current is higher than the corresponding threshold, the slag adding speed is increased.

4. The method according to claim 1, characterized in that: During the filling stage, the power or melting speed is gradually reduced, the filling time is ≥45 minutes, and the furnace cooling time is 50-90 minutes.

5. The method according to claim 1, characterized in that During electroslag remelting, the slag used contains 65-75% CaF2 and 25-35% Al2O3 by weight, and the slag usage is 22-30kg / ton of steel; 25-35% of the slag is added in the preparation stage, and the remaining slag is added in the arc starting stage.

6. The method according to claim 1, characterized in that Before electroslag remelting, the method further comprises: baking and heating the electrode rod, wherein the baking heating temperature is 820-860° C., the heating rate is ≤60° C. / h, and the baking heating time is 6-8h.

7. The method according to claim 1, characterized in that Within 35 minutes before pouring, ensure that the pouring pipe is blown with argon for 15 to 30 minutes. During the pouring process, the argon pressure is controlled at 0.20 to 0.50 MPa. The height between the ladle water inlet and the center pouring pipe gate is controlled to be ≤150 mm. The amount of protective slag is 1.5 to 2.5 kg / t. The ingot body pouring time is 420 to 600 seconds, and the riser pouring time is 240 to 300 seconds.

8. The method according to claim 1, characterized in that During the VD furnace refining process, the argon blowing flow rate is maintained at ≥120L / min for 15~20min. The argon blowing flow rate is reduced before breaking the vacuum. After breaking the vacuum, the lid is closed and stirred for 5~10min. The static argon blowing is ≥15min and the bag temperature is 1490~1500℃.

9. The method according to claim 1, characterized in that: During the annealing process, the heating rate is 30~50℃ / h, the heating temperature is 840~860℃, the holding time is 13~15h, and after the holding is completed, it is slowly cooled to ≤400℃ at a cooling rate of ≤20℃ / h before being taken out of the furnace.

10. The method according to claim 1, characterized in that The low-segregation high-carbon stainless steel billet has a carbon content greater than 0.5%, a carbon segregation index of 1.5-2.0, a center porosity level of 0, a center shrinkage level of 0, and a center segregation level of 0.

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