A method for electroslag remelting chromium-molybdenum series hot work die steel

Abstract

A method for electroslag remelting chromium-molybdenum series hot work die steel, wherein the electroslag consumable electrode is subjected to electroslag remelting under the protection of argon gas, and the SiO2 content in the premelted slag is determined according to the Si content in the steel and the Al2O3 content in the premelted slag. The specific relationship is as follows: [SiO2]% = [(a + 0.66) × (0.78 × b 1 / 3 + 1)]%, where 0.7 ≤ a ≤ 1.3, [Si]% = a%, [Al2O3]% = b%, and [SiO2]% is the mass percentage content of SiO2 in the premelted slag, [Si]% is the mass percentage content of Si in the consumable electrode, and [Al2O3]% is the mass percentage content of Al2O3 in the premelted slag. The present invention significantly reduces the burning loss of Si element in the electroslag ingot, and the recovery rate is stable above 95%.

Description

Technical Field

[0001] The present invention belongs to the technical field of ferrous metallurgy, specifically to the technical field of electroslag remelting. Background Art

[0002] Chromium-molybdenum hot work die steel has excellent comprehensive mechanical properties, good thermal fatigue resistance, thermal stability, oxidation resistance and liquid metal erosion resistance, as well as good hardenability, and is widely used in aluminum alloy die-casting dies, precision forging dies, hot forging punches, hot extrusion dies, hot shearing dies, hot rolling rolls and various hot work dies working under impact and rapid cooling conditions.

[0003] At present, the smelting of chromium-molybdenum hot work die steel mainly adopts the production process routes such as electric arc furnace smelting, LF vacuum refining, ingot casting, electroslag remelting or related smelting process routes. However, in order to obtain excellent ingots with high purity, high density, uniform structure and good forgeability, the electroslag remelting process is often selected for the smelting process before forging.

[0004] After electroslag remelting chromium-molybdenum hot work die steel, there are many pores inside the electroslag ingot, especially at the bottom of the electroslag ingot, which is honeycomb-shaped in severe cases. The main reason is that the carbon in the consumable electrode reacts with oxygen to generate gas. Since the metal molten pool is relatively deep, the gas cannot diffuse to the front of solidification in time, thus forming pores in the ingot. This requires that the melting speed be controlled at a relatively low level during the electroslag process of such steel grades to reduce the depth of the molten pool. This can not only effectively avoid the generation of pores inside the electroslag ingot, but also effectively ensure the uniformity of the solidification structure and reduce the segregation of the ingot. However, the low melting speed control is likely to lead to poor surface quality of the electroslag ingot and low product yield, so it is necessary to accurately control the electroslag melting speed process parameters. And during the electroslag remelting process of such steel grades, the Si element is often severely burned, and the loss amount is as high as more than 20%. In severe cases, it directly leads to the scrapping of the electroslag ingot products. How to accurately control the Si element content in the steel has also become the key to the electroslag metallurgy of such steel grades.

[0005] In order to improve the physical and chemical properties such as the remanent magnetism and coercivity of chromium-molybdenum hot work die steel, during the development of new chromium-molybdenum hot work die steel, the Mo content is increased from the conventional 1.1% - 1.75% to more than 2.5%. After the electroslag smelting of such chromium-molybdenum hot work die steel, the cooling time of the ingot in the water-cooled mold is too long, and cracks are easily generated on the ingot body. This requires that the electroslag ingot be hot-discharged under certain temperature conditions and then stress-relieved annealing be carried out to avoid the generation of cracks on the ingot body. Summary of the Invention

[0006] The technical problem solved by the present invention is to provide a method for electroslag remelting chromium-molybdenum hot work die steel, so that the composition of the electroslag ingot of chromium-molybdenum hot work die steel is accurately controlled and there are no pores inside.

[0007] To solve the above technical problems, the technical solution of the present invention is: a method for electroslag remelting chromium-molybdenum series hot work die steel, wherein the electroslag consumable electrode is subjected to electroslag remelting under the protection of argon gas, and the SiO2 content in the premelted slag is determined according to the Si content in the steel and the Al2O3 content in the premelted slag. The specific relationship is as follows: [SiO2]% = [(a + 0.66) × (0.78 × b 1 / 3 + 1)]%, where 0.7 ≤ a ≤ 1.3, [Si]% = a%, [Al2O3]% = b%, and [SiO2]% is the mass percentage content of SiO2 in the premelted slag, [Si]% is the mass percentage content of Si in the consumable electrode, and [Al2O3]% is the mass percentage content of Al2O3 in the premelted slag.

[0008] When the SiO2 content in the premelted slag is lower than the SiO2 content calculated according to the formula [SiO2]% = [(a + 0.66) × (0.78 × b 1 / 3 + 1)]% of the present invention, a part of SiO2 is added during the remelting process so that the total amount of SiO2 in the slag is the amount calculated according to the above formula. This belongs to the same concept as the present invention and is an embodiment of the present invention.

[0009] Furthermore, for the premelted slag, except for SiO2, the other components and their mass percentage contents are: CaF2 55% - 58%, CaO 18% - 21%, Al2O3 15% - 18%, and MgO 3% - 5%.

[0010] Furthermore, after the electroslag smelting is completed, hot demoulding is carried out at a temperature above 600 °C for the electroslag ingot. After demoulding, the electroslag ingot is put into a heating furnace for stress relief annealing, held at 650 °C - 750 °C for 2 h - 3 h, and then slowly cooled in the furnace to below 400 °C.

[0011] Furthermore, the premelted slag is used after being baked at 500 °C - 600 °C for at least 6 h.

[0012] Furthermore, during the remelting period of smelting, a lower melting speed control with a melting speed of 2.7 kg / min - 3.2 kg / min is adopted.

[0013] Furthermore, during the remelting period of smelting, a higher voltage of 45 V - 48 V and a lower current of 4400 A - 4700 A are adopted.

[0014] Furthermore, the filling ratio of the electroslag consumable electrode is 0.6 - 0.67. The filling ratio is the ratio of the diameter of the consumable electrode to the diameter of the mold.

[0015] Furthermore, the electroslag remelting equipment adopts a single-phase single-pole, ingot-pulling type 1 t protective atmosphere electroslag furnace with an AC power supply mode, and is matched with a Φ300 × 1300 mm mold.

[0016] For the steel composition, slag components, etc. described in the present invention, their contents are all mass percentages.

[0017] The beneficial effects produced by adopting the above technical solutions are as follows:

[0018] Through argon atmosphere protection melting and pre-melted slag system adjustment in the present invention, the addition amount of SiO2 in the slag is accurately determined according to the Si content in the smelted steel grade and the Al2O3 content in the slag system, effectively inhibiting the reaction process during the remelting process, significantly reducing the burning loss of Si element in the electroslag ingot, with the recovery rate stable above 95%, avoiding the increase of Al in the electroslag ingot; through low melting speed control during the electroslag process, not only effectively avoiding the generation of internal pores in the electroslag ingot, but also ensuring the uniformity of the solidification structure, and the surface of the electroslag ingot is smooth and defect-free; after electroslag smelting, hot demoulding is carried out under certain temperature conditions, and then stress relief annealing is carried out, avoiding the generation of ingot body cracks. Specific embodiments

[0019] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following further elaborates on the present invention in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] Examples 1 - 5

[0021] The target composition requirements (wt) of the chromium-molybdenum series hot work die steel for electroslag remelting are: C 0.3% - 0.6%, Si 0.7% - 1.3%, Mn 0.2% - 0.5%, Cr 4.5% - 5.5%, Mo 2.5% - 3.5%, V 0.7% - 1%, Al ≤ 0.02%, P ≤ 0.01%, S ≤ 0.01%. The equipment uses a single-phase single-pole, ingot-pulling type 1t protective atmosphere electroslag furnace with AC power supply, and is matched with a Φ300×1300mm mold. The processes of each step are as described below:

[0022] Consumable electrode preparation: Use a steel grade with the same target composition as the above chromium-molybdenum series hot work die steel as the consumable electrode. The electrode diameter is Φ180mm - Φ200mm. After grinding the electrode surface, it is welded to the auxiliary electrode;

[0023] Pre-melted slag preparation: Bake 30kg of slag material in a furnace at 500°C - 600°C for more than 6h. The composition of the pre-melted slag is: CaF2 55% - 58%, CaO 18% - 21%, Al2O3 15% - 18%, MgO 3% - 5%. The content of SiO2 is determined according to the Si content in the steel and the Al2O3 content. The specific relationship is: [SiO2]% = [(a + 0.66)×(0.78×b 1 / 3 + 1)]%, where [Si]% = a%, [Al2O3]% = b%.

[0024] Charging: Place an ingot guide plate of the same material on the bottom water tank of the electroslag furnace, and place arc-striking chips of the same material at the center of the ingot guide plate; install the mold, protective hood, and consumable electrode.

[0025] Argon protection: Continuously introduce argon as the protective gas during the entire smelting process. The argon flow rate is 80 - 200 L / min, ensuring that the oxygen content in the atmosphere during the entire smelting process is ≤ 100 ppm and the argon purity is ≥ 99.99%.

[0026] Slag melting period: Start arc striking by electrifying. After the arc is stable, slowly add slag materials. The slag addition time is controlled within 10 min, and the slag melting time is set at 25 min. At the end of the slag melting period, the current rises to 4400 A - 4700 A and the voltage rises to 45 V - 48 V.

[0027] Remelting period: Enter the remelting period after the slag melting period is completed. The melting rate during the remelting period is 2.7 kg / min - 3.2 kg / min. The voltage adjustment range is 45 V - 48 V, and the current adjustment range is 4400 A - 4700 A. The melting rate during the smelting process is the target value, and the current and voltage are the adjusted values, ensuring that the melting rate is within the range of 2.7 kg / min - 3.2 kg / min.

[0028] Feeding period: Start feeding when the electrode remains 45 kg, and end after 25 min of feeding. Slowly reduce the voltage and current during feeding.

[0029] Demolding: Demold 20 - 30 min after the smelting is completed, ensuring that the temperature of the electroslag ingot is > 600 °C. After demolding, place the electroslag ingot in a heating furnace for stress relief annealing, keep it at 650 °C - 750 °C for 2 - 3 h, and slowly cool it in the furnace to below 400 °C.

[0030] Examples 1 - 5 are produced according to the above technological process. The specific steel grade component contents and production process parameters are as follows:

[0031] Example 1:

[0032] Preparation of consumable electrode: The consumable electrode for electroslag remelting in this example is a chromium-molybdenum series hot work die steel with a specification of Φ180×2000 mm, and the filling ratio is 0.6. Composition: C 0.423%, Si 0.700%, Mn 0.276%, Cr 5.44%, Mo 2.78%, V 0.786%, Al 0.0047%, P 0.0046%, S 0.0078%, and the balance is iron and inevitable impurities.

[0033] Preparation of premelted slag: Bake 30 kg of slag materials in a furnace at 500 °C for 6 h. The composition of the premelted slag is: CaF2 57%, CaO 21%, Al2O3 15%, MgO 3%, SiO2 4%. The content of SiO2 is determined according to the Si content and Al2O3 content in the steel:

[0034] [SiO2]% = [(a + 0.66) × (0.78 × b 1 / 3 + 1)]% = [(0.700 + 0.66) × (0.78 × 15 1 / 3 + 1)]% = 4%. Where [Si]% = a%, that is, a = 0.700; [Al2O3]% = b%, that is, b = 15.

[0035] The melting rate during the remelting period is 2.7 kg / min. The melting rate during the smelting process is the target value, and the current and voltage are adjusted values. The voltage adjustment range is 45 V - 46 V, and the current adjustment range is 4400 A - 4500 A, ensuring that the melting rate is within the range of 2.65 kg / min - 2.75 kg / min;

[0036] Demold 20 min after the melting is completed. The temperature of the electroslag ingot is 768 °C. After demolding, the electroslag ingot is put into a heating furnace for stress relief annealing, kept at 650 °C for 2 h, and slowly cooled in the furnace to below 400 °C.

[0037] Saw the electroslag ingot 30 mm above the bottom ingot guide plate with a sawing machine, check the pore condition at the bottom and take samples for composition and microstructure detection. The results of chemical composition detection are C 0.414%, Si 0.687%, Mn 0.271%, Cr 5.41%, Mo 2.76%, V 0.784%, Al 0.0098%, P 0.0056%, S 0.0025%. The recovery rate of Si element is ≥95%, and the increase of Al in the electroslag ingot is effectively avoided. The composition meets the requirements, and the solidification structure is uniform. The electroslag ingot is detected by an ultrasonic flaw detector without cracks and holes.

[0038] Example 2:

[0039] Preparation of consumable electrode: The consumable electrode for electroslag remelting in this example is a chromium-molybdenum series hot work die steel with a specification of Φ180×2000 mm, and the filling ratio is 0.6. The composition is: C 0.523%, Si 0.982%, Mn 0.475%, Cr 5.21%, Mo 3.42%, V 0.92%, Al 0.0073%, P 0.0051%, S 0.0068%, and the balance is iron and inevitable impurities.

[0040] Preparation of premelted slag: Bake 30 kg of slag materials in a furnace at 600 °C for 8 h. The composition of the premelted slag is: CaF2 55%, CaO 18%, Al2O3 18%, MgO 5%, SiO2 4%. The content of SiO2 is determined according to the Si content and Al2O3 content in the steel.

[0041] [SiO2]% = [(a + 0.66) × (0.78 × b 1 / 3 + 1)]% = [(0.982 + 0.66) × (0.78 × 18 1 / 3 + 1)]% = 5%. Where [Si]% = a%, that is, a = 0.982; [Al2O3]% = b%, that is, b = 18.

[0042] Remelting period: After the slag melting period is completed, enter the remelting period. The melting rate in the remelting period is 3.2 kg / min. The melting rate during the smelting process is the target value, and the current and voltage are the adjusted values. The voltage adjustment range is 47 V - 48 V, and the current adjustment range is 4600 A - 4700 A, ensuring that the melting rate is within the range of 3.15 kg / min - 3.25 kg / min.

[0043] Demoulding: Demould 25 min after the smelting is completed. The temperature of the electroslag ingot is 683 °C. After demoulding, the electroslag ingot is put into a heating furnace for stress relief annealing, kept at 750 °C for 3 h, and slowly cooled in the furnace to below 400 °C.

[0044] Use a sawing machine to saw cut 30 mm above the ingot guide plate at the bottom of the electroslag ingot, check the pore condition at the bottom and take samples for composition and microstructure detection. The chemical composition detection results are: C 0.515%, Si 0.961%, Mn 0.468%, Cr 5.21%, Mo 3.41%, V 0.92%, Al 0.012%, P 0.0051%, S 0.0068%. The recovery rate of Si element is ≥95%, and the increase of Al in the electroslag ingot is effectively avoided. The composition meets the requirements, and the solidification structure is uniform. The electroslag ingot is detected by an ultrasonic flaw detector and has no cracks and no holes.

[0045] Example 3:

[0046] Preparation of consumable electrode: The consumable electrode for electroslag remelting in this example is a chromium-molybdenum series hot work die steel with a specification of Φ200×1700 mm, and the filling ratio is 0.67. The composition is: C 0.589%, Si 1.30%, Mn 0.226%, Cr 4.71%, Mo 3.45%, V 0.96%, Al 0.0054%, P 0.0071%, S 0.0053%, and the balance is iron and unavoidable impurities.

[0047] Preparation of premelted slag: Bake 30 kg of slag materials in a furnace at 550 °C for 6 h. The composition of the premelted slag is: CaF2 56.7%, CaO 18%, Al2O3 16%, MgO 3.5%, SiO2 5.8%. The content of SiO2 is determined according to the Si content and Al2O3 content in the steel.

[0048] [SiO2]% = [(a + 0.66) × (0.78 × b 1 / 3 + 1)]% = [(1.3 + 0.66) × (0.78 × 16 1 / 3 + 1)]% = 5.8%, where [Si]% = a%, that is, a = 1.3; [Al2O3]% = b%, that is, b = 16.

[0049] Remelting period: After the slag melting period is completed, enter the remelting period. The melting rate in the remelting period is 3 kg / min. The melting rate during the smelting process is the target value, and the current and voltage are the adjusted values. The voltage adjustment range is 46 V - 47 V, and the current adjustment range is 4500 A - 4600 A, ensuring that the melting rate is within the range of 2.95 kg / min -

[0050] 3.05 kg / min;

[0051] Feeding period: Start feeding when the electrode remains 45 kg, and end after 25 min of feeding. Slowly reduce the voltage and current during feeding;

[0052] Demoulding: Demould 30 min after the smelting is completed. The temperature of the electroslag ingot is 635 °C. After demoulding, the electroslag ingot is put into a heating furnace for stress relief annealing, kept at 700 °C for 2.5 h, and slowly cooled in the furnace to below 400 °C.

[0053] Saw the electroslag ingot 30 mm above the ingot guide plate at the bottom with a sawing machine, check the pore condition at the bottom and take samples for composition and microstructure detection. The results of chemical composition detection are C 0.572%, Si 1.263%, Mn 0.212%, Cr 4.69%, Mo 3.45%, V 0.95%, Al 0.0111%, P 0.0056%, S 0.0025%. The recovery rate of Si element is ≥95%, and the increase of Al in the electroslag ingot is effectively avoided. The composition meets the requirements, and the solidification structure is uniform. The electroslag ingot is detected by an ultrasonic flaw detector without cracks and holes.

[0054] Example 4:

[0055] Consumable electrode preparation: In this embodiment, the consumable electrode for electroslag remelting is a chromium-molybdenum series hot work die steel ingot with a specification of Φ190×1700mm, the filling ratio is 0.63, and the composition is: C 0.322%, Si 0.814%, Mn 0.326%, Cr 4.67%, Mo 2.98%, V 0.726%, Al 0.0066%, P 0.0067%, S 0.0061%, and the balance is iron and unavoidable impurities.

[0056] Premelted slag preparation: Bake 30 kg of slag material in a furnace at 550°C for 6 h. The composition of the premelted slag is: CaF2 55.5%, CaO 18%, Al2O3 18%, MgO 4%, SiO2 4.5%. The content of SiO2 is determined according to the Si content and Al2O3 content in the steel.

[0057] [SiO2]% = [(a + 0.66)×(0.78×b 1 / 3 + 1)]% = [(0.814 + 0.66)×(0.78×18 1 / 3 + 1)]% = 4.5%, where [Si]% = a%, that is, a = 0.814; [Al2O3]% = b%, that is, b = 18.

[0058] Remelting period: After the slag melting period is completed, it enters the remelting period. The melting rate in the remelting period is 3 kg / min. The melting rate during the smelting process is the target value, and the current and voltage are adjusted values. The voltage adjustment range is 46 V to 47 V, and the current adjustment range is 4500 A to 4600 A, ensuring that the melting rate is within the range of 2.95 kg / min to

[0059] 3.05 kg / min;

[0060] Demoulding: Demoulding is carried out 25 minutes after the melting is completed. The temperature of the electroslag ingot is 697°C. After demoulding, the electroslag ingot is put into a heating furnace for stress relief annealing, kept at 650°C for 3 h, and slowly cooled in the furnace to below 400°C. C 0.322%, Si 0.814%, Mn 0.326%, Cr 4.67%, Mo 2.98%, V 0.726%, P 0.0067%, S 0.0061%

[0061] Saw the electroslag ingot 30 mm above the ingot guide plate at the bottom with a sawing machine, check the pore condition at the bottom and take samples for composition and microstructure detection. The results of chemical composition detection are C 0.314%, Si 0.791%, Mn 0.315%, Cr 4.64%, Mo 2.96%, V 0.722%, Al 0.0102%, P 0.083%, S 0.021%. The recovery rate of Si element is ≥95%, and the increase of Al in the electroslag ingot is effectively avoided. The composition meets the requirements, and the solidification structure is uniform. The electroslag ingot is detected by an ultrasonic flaw detector without cracks and holes.

[0062] Example 5:

[0063] Consumable electrode preparation: The consumable electrode for electroslag remelting in this example is an ingot of chromium-molybdenum hot work die steel with a specification of Φ200×1700mm, the filling ratio is 0.67, and the composition is: C 0.512%, Si 1.244%, Mn 0.291%, Cr 5.32%, Mo 2.73%, V 0.93%, Al 0.0044%, P 0.0052%, S 0.0066%, and the balance is iron and unavoidable impurities.

[0064] Preparation of premelted slag: Bake 30 kg of slag material in a furnace at 600°C for 7 h. The composition of the premelted slag is: CaF2 55.4%, CaO 21%, Al2O3 15%, MgO 3%, SiO2 5.6%. The content of SiO2 is determined according to the Si content and Al2O3 content in the steel.

[0065] [SiO2]% = [(a + 0.66)×(0.78×b 1 / 3 + 1)]% = [(1.244 + 0.66)×(0.78×15 1 / 3 + 1)]% = 5.6%, where [Si]% = a%, that is, a = 1.244; [Al2O3]% = b%, that is, b = 15.

[0066] Remelting period: After the slag melting period is completed, it enters the remelting period. The melting rate in the remelting period is 3.1 kg / min. The melting rate during the smelting process is the target value, and the current and voltage are adjusted values. The voltage adjustment range is 46.5 V to 47.5 V, and the current adjustment range is 4650 A to 4750 A, ensuring that the melting rate is within the range of 3.05 kg / min to 3.15 kg / min.

[0067] Demoulding: Demould 20 min after the smelting is completed. The temperature of the electroslag ingot is 783°C. After demoulding, the electroslag ingot is put into a heating furnace for stress relief annealing, kept at 750°C for 2 h, and slowly cooled in the furnace to below 400°C.

[0068] Saw the electroslag ingot 30 mm above the ingot guide plate at the bottom with a sawing machine, check the pore condition at the bottom and take samples for composition and microstructure detection. The results of chemical composition detection are C 0.503%, Si 1.197%, Mn 0.283%, Cr 5.32%, Mo 2.72%, V 0.92%, Al 0.0118%, P 0.0070%, S 0.0032%. The recovery rate of Si element is ≥95%, and the increase of Al in the electroslag ingot is effectively avoided. The composition meets the requirements, and the solidification structure is uniform. The electroslag ingot is detected by an ultrasonic flaw detector without cracks and holes.

[0069] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent substitutions can still be made to the present invention, and any modification or partial substitution without departing from the spirit and scope of the present invention shall be covered by the scope of the claims of the present invention.

Claims

1. A method for electroslag remelting chromium-molybdenum series hot work die steel, characterized in that, The electroslag consumable electrode is subjected to electroslag remelting under the protection of argon gas. The SiO2 content in the premelted slag is determined according to the Si content in the steel and the Al2O3 content in the premelted slag. The specific relationship is as follows: [SiO2]% = [(a + 0.66) × (0.78 × b 1 / 3 + 1)]%, where 0.7 ≤ a ≤ 1.3, [Si]% = a%, [Al2O3]% = b%. Here, [SiO2]% is the mass percentage content of SiO2 in the premelted slag, [Si]% is the mass percentage content of Si in the consumable electrode, and [Al2O3]% is the mass percentage content of Al2O3 in the premelted slag.

2. The method for electroslag remelting chromium-molybdenum series hot work die steel according to claim 1, characterized in that, For the pre-melted slag, except for SiO2, the other components and their mass percentages are as follows: CaF2 55% - 58%, CaO 18% - 21%, Al2O3 15% - 18%, and MgO 3% - 5%.

3. A method for electroslag remelting chromium-molybdenum series hot work die steel according to claim 1, characterized in that, After the electroslag remelting is completed, hot demolding is carried out on the electroslag ingot under the condition of above 600°C. After demolding, the electroslag ingot is put into a heating furnace for stress relief annealing, kept at 650°C - 750°C for 2h - 3h, and then slowly cooled in the furnace to below 400°C.

4. A method for electroslag remelting chromium-molybdenum series hot work die steel according to claim 1, characterized in that, The pre-melted slag is used after being baked at 500°C - 600°C for at least 6h.

5. A method for electroslag remelting chromium-molybdenum series hot work die steel according to claim 1, characterized in that, The melting rate during the remelting period of smelting is 2.7 kg / min - 3.2 kg / min.

6. A method for electroslag remelting chromium-molybdenum series hot work die steel according to claim 1, characterized in that, During the remelting period of smelting, a voltage of 45V - 48V and a current of 4400A - 4700A are adopted.

7. A method for electroslag remelting chromium-molybdenum series hot work die steel according to claim 1, characterized in that, The filling ratio of the electroslag consumable electrode is 0.6 - 0.

67.

8. A method for electroslag remelting chromium-molybdenum series hot work die steel according to claim 1, characterized in that, The electroslag remelting equipment uses a single-phase single-pole, ingot-pulling type 1t protected atmosphere electroslag furnace with AC power supply, and is matched with a Φ300×1300mm mold.