A method for producing steel for gear shafts in an ecological electric furnace process

Abstract

The present invention discloses a method for producing steel for gear shafts in an ecological electric furnace process. The method adopts a 100t ECOARC ecological electric furnace + LF + RH + 210mm*210mm continuous casting smelting and frying process to produce a Φ60mm gear shaft steel bar, which not only ensures the mechanical properties, high hardness and high steel purity of the finished steel 40CrMnMoA for gear shafts, but also ensures the surface quality level of carburized gear shaft steel. The present invention ensures the surface quality and impact performance of the product through reasonable component design and production process. The low-multiple structure, non-metallic inclusions and hardness of the finished steel meet the requirements of high-end products. The gear shaft steel 40CrMnMoA with excellent mechanical properties, high hardness and high steel purity is developed to meet the new market demand; it achieves a technical breakthrough in the batch production of carburized gear shaft steel 40CrMnMoA bars in the converter continuous casting process.

Description

Technical Field

[0001] The invention belongs to the technical field of special steel production, and specifically relates to a method for producing steel for gear shafts in an ecological electric furnace process. Background Art

[0002] The gear shaft is a mechanical part that supports the rotating parts and rotates with them to transmit motion, torque or bending moment. Its working environment is harsh, and the comprehensive performance requirements of the gear shaft steel, such as wear resistance and fatigue life, are very strict. As an important part of the transmission device, the gear shaft has strict quality requirements; the quality of the gear shaft steel directly affects the service life and wear resistance of the transmission device, and even affects the safety of the entire transmission device working process. Summary of the invention

[0003] In order to meet the quality requirements of gear shaft steel, the purpose of the present invention is to provide a method for producing steel for gear shaft using an ecological electric furnace process. The method adopts a 100t ECOARC ecological electric furnace + LF + RH + 210mm*210mm continuous casting smelting process to produce 40CrMnMoA bars of steel for gear shaft, which not only ensures the mechanical properties, high hardness and high steel purity of the finished steel 40CrMnMoA for gear shaft, but also ensures the surface quality level of carburized gear shaft steel 40CrNiMoA.

[0004] In order to achieve the above-mentioned purpose of the invention, the present invention has developed 40CrMnMoA steel for gear shafts with excellent mechanical properties, high hardness and high steel purity to meet the requirements of high-end products; and achieved a breakthrough in the mass production of carburized 40CrMnMoA steel bars for gear shafts by the converter continuous casting process.

[0005] The present invention provides a method for producing steel for gear shafts in an ecological electric furnace process, the method comprising the following steps: 100t ECOARC ecological electric furnace+LF+RH+210mm*210mm continuous casting billet→heating in a heating furnace→rolling→insulation→finishing→inspection→packaging and storage→delivery.

[0006] The composition of the molten steel in the method steps is controlled by mass percentage to be C: 0.38%-0.42%, Si: 0.22%-0.35%, Mn: 0.55%-0.70%, P≤0.015%, S≤0.008%, Cr: 0.65%-0.80%, Ni: 1.30%-1.55%, Cu≤0.15%, Mo: 0.16%-0.23%; the remainder is iron and unavoidable impurities.

[0007] A method for producing steel for gear shafts in the above-mentioned ecological electric furnace process, further, in the ecological electric furnace smelting process, scrap steel accounts for 100%; the scrap steel loading amount is 115-120t, the steel tapping temperature is 1695-1700℃, the C is controlled to be 0.15-0.20% when tapping, P≤0.010%, slag, pre-deoxidizer, and ferroalloy are added when 1 / 4-1 / 3 of the steel is tapped, and the steel tapping amount is 103-107t. The amount of alloy added per ton of steel: 12.5-13.5Kg / t of silicon manganese, 15-15.5Kg / t of high carbon ferrochrome, and 1.8-1.9m / t of aluminum wire segment (Φ10mm). The amount of auxiliary materials added per ton of steel: 29-30Kg / t of dolomite, 48-49Kg / t of active lime, 30-31Kg / t of coke particles, and 5-5.2Kg / t of graphite pellets.

[0008] In the above technical scheme, further, in the LF furnace process, a large current is used to heat up the slag, and when the slag surface fluctuates and the molten steel and the arc are not exposed, active lime is added. After 5 minutes, the chemical composition is analyzed for the first time, and alloy is added according to the target value of the chemical composition, and carbon is added to promote rapid melting and homogenization of the alloy and carbon powder. When the temperature of molten steel reaches 1555-1565℃, add 2-3kg / t of diffusion deoxidizer for diffusion deoxidation, close the furnace door for 10 minutes, and take a second sample to analyze the chemical composition when the temperature of molten steel reaches 1620-1630℃ to confirm the deviation of the content of each chemical element from the target value. After the second sample is taken, the smelting cycle is 60-80 minutes, and the alloy is added: 1.0-1.1kg / t of ferrosilicon, 6.2-6.3kg / t of high carbon ferromanganese, 3.6-3.7kg / t of high carbon ferrochrome, 1.5-1.6kg / t of alumina balls, 4.5-4.6kg / t of ferromolybdenum, and 1-1.1m / t of aluminum wire (Φ10mm). Add auxiliary materials: 4-4.2kg / t of active lime and 1-1.1kg / t of silicon carbide.

[0009] In the above technical scheme, further, in the RH refining process, the inlet temperature is 1670-1675°C, the operation time is 28min-32min, and the argon pressure is controlled at 0.1-0.3MPa before the vacuum pump is started, so that the slag surface moves slightly and the molten steel is not exposed. When the vacuum degree reaches 100Pa, the timing starts and the holding time is 10-15min. At the same time, the argon pressure is adjusted to 0.3-0.5MPa. After the static argon blowing is completed, 2-2.2 meters / t of silicon-calcium alloy cored wire (Φ14mm) and 0.6-0.7kg / t of covering agent are added, and the outlet temperature is 1635-1640°C.

[0010] In the above technical scheme, further, in the continuous casting process, the temperature of the ladle arriving at the continuous casting station is 1615-1620°C, the molten steel volume is 95-105t, the H in the middle ladle is controlled ≤2ppm, the whole process is protected casting, and the crystallizer protective slag uses medium carbon steel protective slag.

[0011] In the above technical scheme, further, in the heating process, the temperature of the heating furnace is 300℃~540℃, the temperature of the preheating section is 650~700℃, and the time is 1.0~1.5h; the temperature of the heating section 2 is 840℃~880℃, and the time is 1.0~1.5h; the temperature of the heating section 1 is required to be 1190~1220℃, the time is 1.0~1.5h, and the average temperature is 1.0~1.5h; the temperature of the equalizing section is required to be 1180℃~1210℃, the time is 1.0~1.5h, and the average temperature is 1.5h~2h; the steel tapping temperature is 1170℃~1190℃.

[0012] In the above technical solution, further, in the rolling process, the rolling process of the small bar Φ60mm is: the first pass is 166-166.3mm high and 227-227.3mm wide; the second pass is 154-154.3mm high and 191-191.3mm wide; the third pass is 137-137.3mm high and 180-180.3mm wide; the fourth pass is 150-150.3mm high and 149-149.3mm wide; the fifth pass is 98-98.3mm high and 172-172.3mm wide; the sixth pass is 114-114.3mm high and 114-114.3mm wide. 14.3mm high, 114~114.3mm wide; the 7th pass is 74~74.3mm high, 134~134.3mm wide; the 8th pass is 88~88.3mm high, 88~88.3mm wide; the 9th pass is 61~61.3mm high, 99~99.3mm wide; the 10th pass is 70~70.3mm high, 70~70.3mm wide; the 11th pass is 54~54.3mm high, 76~76.3mm wide; the 12th pass is 60~60.3mm high, 60~60.3mm wide, and the finished product is produced after 12 passes.

[0013] A steel for gear shafts produced by the above-mentioned ecological electric furnace process.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] ① The 100t ECOARC ecological electric furnace + LF + RH + 210mm*210mm smelting process and rolling process are used to produce 40CrMnMoA steel bars for gear shafts. The production specification is Φ60mm, which meets the mechanical property requirements and ensures the purity of the steel.

[0016] ② Reasonable component design and production process ensure surface quality and impact performance.

[0017] ③ The macrostructure, non-metallic inclusions and hardness of the finished steel all meet the requirements of high-end products, achieving a technological breakthrough in the converter continuous casting process for mass production of 40CrMnMoA steel bars for carburized gear shafts. DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with specific examples, but the present invention is not limited in any way. To avoid redundant description, the raw materials in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified.

[0019] Example 1

[0020] 1Chemical composition

[0021] The internal control chemical composition was determined to be C: 0.40%, Si: 0.28%, Mn: 0.58%, P: 0.010%, S: 0.006%, Cr: 0.70%, Ni: 1.42%, Cu: 0.05%, and Mo: 0.19%.

[0022] 2 Design of production process parameters for 40CrMnMoA electric furnace continuous casting of gear shaft steel

[0023] Process route: 100t ECOARC ecological electric furnace + LF + RH + 210mm*210mm continuous casting billet → heating in heating furnace → rolling → insulation → finishing → inspection → packaging and storage → delivery.

[0024] (1) Ecological electric furnace smelting: scrap steel accounts for 100%; scrap steel loading is 118t, tapping temperature is 1698℃, C is 0.17% and P is 0.008% when tapping, slag, pre-deoxidizer and ferroalloy are added when 1 / 4 of the steel is tapped, and the tapping amount is 105t. Alloy addition per ton of steel: silicon manganese 12.8Kg / t, high carbon ferrochrome 15Kg / t, aluminum wire segment (Φ10mm) 1.8m / t. Auxiliary materials added per ton of steel: dolomite 29Kg / t, active lime 48Kg / t, coke particles 30Kg / t, graphite pellets 5Kg / t.

[0025] (2) LF furnace: high current is used to heat up the slag. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime is added. After 5 minutes, the chemical composition is analyzed for the first time. According to the target value of the chemical composition, alloy is added and carbon is added to promote the rapid melting and homogenization of the alloy and carbon powder. When the temperature of the molten steel reaches 1559℃, 2kg / t of diffusion deoxidizer is added for diffusion deoxidation. The furnace door is closed for 10 minutes. When the temperature of the molten steel reaches 1625℃, the chemical composition is analyzed for the second time to confirm the deviation value of the content of each chemical element from the target value. After the second sample is taken away, the smelting cycle is 68 minutes. Alloy is added: 1.0kg / t of ferrosilicon, 6.2kg / t of high carbon ferromanganese, 3.6kg / t of high carbon ferrochromium, 1.5kg / t of alumina balls, 4.5kg / t of ferromolybdenum, and 1m / t of aluminum wire (Φ10mm). Supplementary materials: 4kg / t of active lime and 1kg / t of silicon carbide.

[0026] (3) RH refining: the inlet temperature is 1672℃, the operation time is 28min~32min, the argon pressure is controlled at 0.15MPa before the vacuum pump is started, so that the molten steel is not exposed when the slag surface moves slightly. When the vacuum degree reaches 100Pa, the timing starts and the time is maintained for 15min. At the same time, the argon pressure is adjusted to 0.4MPa. After the static argon blowing is completed, 2m / t of silicon-calcium alloy cored wire (Φ14mm) and 0.6kg / t of covering agent are added. The outlet temperature is 1637℃.

[0027] (4) Continuous casting: The temperature of the ladle at the station is 1618℃, the amount of molten steel is 98t, the H in the tundish is controlled at 1.6ppm, the whole process is protected casting, and the mold protection slag uses medium carbon steel protection slag.

[0028] (5) Heating process

[0029] Heating process: the temperature entering the heating furnace is 380℃, the temperature of the preheating section is required to be 660℃, and the time is 1.2h; the temperature of the heating section 2 is required to be 860℃, and the time is 1.3h; the temperature of the heating section 1 is required to be 1196℃, and the time is 1.2h, and the average temperature is 1.3h; the temperature of the average heating section is required to be 1195℃, and the time is 1.3h, and the average temperature is 1.7h; the steel tapping temperature is 1185℃.

[0030] (6) Rolling process of product specification Φ60mm:

[0031] Small bar Φ60mm rolling process: the 1st pass is 166mm high and 227mm wide, the 2nd pass is 154mm high and 191mm wide; the 3rd pass is 137mm high and 180mm wide; the 4th pass is 150mm high and 149mm wide; the 5th pass is 98mm high and 172mm wide; the 6th pass is 114mm high and 114mm wide; the 7th pass is 74mm high and 134mm wide; the 8th pass is 88mm high and 88mm wide; the 9th pass is 61mm high and 99mm wide; the 10th pass is 70mm high and 70mm wide; the 11th pass is 54mm high and 76mm wide; the 12th pass is 60mm high and 60mm wide, and the finished product is produced after 12 passes.

[0032] The macrostructure and impact performance test results of the finished product of Example 1 are shown in Tables 1 and 2.

[0033] Example 2

[0034] 1Chemical composition

[0035] The internal control chemical composition was determined to be C: 0.40%, Si: 0.26%, Mn: 0.60%, P: 0.011%, S: 0.004%, Cr: 0.69%, Ni: 1.37%, Cu: 0.04%, and Mo: 0.19%.

[0036] 2 Design of production process parameters for 40CrMnMoA electric furnace continuous casting of gear shaft steel

[0037] Process route: 100t ECOARC ecological electric furnace + LF + RH + 210mm*210mm continuous casting billet → heating in heating furnace → rolling → insulation → finishing → inspection → packaging and storage → delivery.

[0038] (1) Ecological electric furnace smelting: scrap steel accounts for 100%; scrap steel loading is 116t, tapping temperature is 1697℃, C is 0.18% and P is 0.009% when tapping, slag, pre-deoxidizer and ferroalloy are added when 1 / 4 of the steel is tapped, and the tapping amount is 105t. Alloy addition per ton of steel: silicon manganese 12.8Kg / t, high carbon ferrochrome 15Kg / t, aluminum wire segment (Φ10mm) 1.8m / t. Auxiliary materials added per ton of steel: dolomite 30Kg / t, active lime 48Kg / t, coke particles 30Kg / t, graphite pellets 5Kg / t.

[0039] (2) LF furnace: high current is used to heat up the slag. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime is added. After 5 minutes, the chemical composition is analyzed for the first time. According to the target value of the chemical composition, alloy is added and carbon is added to promote the rapid melting and homogenization of the alloy and carbon powder. When the temperature of the molten steel reaches 1559℃, 2kg / t of diffusion deoxidizer is added for diffusion deoxidation. The furnace door is closed for 10 minutes. When the temperature of the molten steel reaches 1625℃, the chemical composition is analyzed for the second time to confirm the deviation value of the content of each chemical element from the target value. After the second sample is taken away, the smelting cycle is 68 minutes. Alloy is added: 1.0kg / t of ferrosilicon, 6.2kg / t of high carbon ferromanganese, 3.6kg / t of high carbon ferrochromium, 1.5kg / t of alumina balls, 4.5kg / t of ferromolybdenum, and 1m / t of aluminum wire (Φ10mm). Supplementary materials: 4kg / t of active lime and 1kg / t of silicon carbide.

[0040] (3) RH refining: the inlet temperature is 1672°C, the operation time is 30 min, the argon pressure is controlled at 0.1 MPa before the vacuum pump is started, so that the slag surface moves slightly and the molten steel is not exposed. When the vacuum degree reaches 100 Pa, the timing starts and the time is maintained for 15 min. At the same time, the argon pressure is adjusted to 0.4 MPa. After the static argon blowing is completed, 2 m / t of silicon-calcium alloy cored wire (Φ14 mm) and 0.6 kg / t of covering agent are added. The outlet temperature is 1637°C.

[0041] (4) Continuous casting: The temperature of the ladle at the station is 1617℃, the amount of molten steel is 98t, the H in the tundish is controlled at 1.7ppm, the whole process is protected casting, and the mold protection slag uses medium carbon steel protection slag.

[0042] (5) Heating process

[0043] Heating process: the temperature entering the heating furnace is 420℃, the temperature of the preheating section is required to be 670℃, and the time is 1.2h; the temperature of the heating section 2 is required to be 850℃, and the time is 1.2h; the temperature of the heating section 1 is required to be 1210℃, and the time is 1.2h, and the average temperature is 1.2h; the temperature of the average heating section is required to be 1195℃, and the time is 1.2h, and the average temperature is 1.6h; the steel tapping temperature is 1185℃.

[0044] (6) Rolling process of product specification Φ60mm:

[0045] Small bar Φ60mm rolling process: the 1st pass is 166mm high and 227mm wide, the 2nd pass is 154mm high and 191mm wide; the 3rd pass is 137mm high and 180mm wide; the 4th pass is 150mm high and 149mm wide; the 5th pass is 98mm high and 172mm wide; the 6th pass is 114mm high and 114mm wide; the 7th pass is 74mm high and 134mm wide; the 8th pass is 88mm high and 88mm wide; the 9th pass is 61mm high and 99mm wide; the 10th pass is 70mm high and 70mm wide; the 11th pass is 54mm high and 76mm wide; the 12th pass is 60mm high and 60mm wide, and the finished product is produced after 12 passes.

[0046] The macrostructure and impact performance test results of the finished product of Example 2 are shown in Tables 1 and 2.

[0047] Example 3

[0048] 1. Optimized design of ingredients

[0049] The internal control chemical composition was determined to be C: 0.41%, Si: 0.27%, Mn: 0.60%, P: 0.010%, S: 0.006%, Cr: 0.70%, Ni: 1.35%, Cu: 0.05%, and Mo: 0.18%.

[0050] 2 Design of production process parameters for 40CrNiMoA electric furnace continuous casting of gear shaft steel

[0051] Process route: 100t ECOARC ecological electric furnace + LF + RH + 210mm*210mm continuous casting billet → heating in heating furnace → rolling → insulation → finishing → inspection → packaging and storage → delivery.

[0052] (1) Ecological electric furnace smelting: scrap steel accounts for 100%; scrap steel loading is 117t, tapping temperature is 1696℃, C is 0.17% and P is 0.010% when tapping, slag, pre-deoxidizer and ferroalloy are added when 1 / 4 of the steel is tapped, and the tapping amount is 105t. Alloy addition per ton of steel: silicon manganese 12.8Kg / t, high carbon ferrochrome 15Kg / t, aluminum wire segment (Φ10mm) 1.8m / t. Auxiliary materials added per ton of steel: dolomite 29Kg / t, active lime 48Kg / t, coke particles 30Kg / t, graphite pellets 5Kg / t.

[0053] (2) LF furnace: high current is used to heat up the slag. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime is added. After 5 minutes, the chemical composition is analyzed for the first time. According to the target value of the chemical composition, alloy is added and carbon is added to promote the rapid melting and homogenization of the alloy and carbon powder. When the temperature of the molten steel reaches 1560℃, 2kg / t of diffusion deoxidizer is added for diffusion deoxidation. The furnace door is closed for 10 minutes. When the temperature of the molten steel reaches 1625℃, the chemical composition is analyzed for the second time to confirm the deviation value of the content of each chemical element from the target value. After the second sample is taken away, the smelting cycle is 65 minutes. Alloy is added: 1.0kg / t of ferrosilicon, 6.2kg / t of high carbon ferromanganese, 3.6kg / t of high carbon ferrochromium, 1.5kg / t of alumina balls, 4.5kg / t of ferromolybdenum, and 1m / t of aluminum wire (Φ10mm). Supplementary materials: 4kg / t of active lime and 1kg / t of silicon carbide.

[0054] (3) RH refining: the inlet temperature is 1672°C, the operation time is 29 min, the argon pressure is controlled at 0.1 MPa before the vacuum pump is started, so that the slag surface moves slightly and the molten steel is not exposed. When the vacuum degree reaches 100 Pa, the timing starts and the time is maintained for 12 min. At the same time, the argon pressure is adjusted to 0.3 MPa. After the static argon blowing is completed, 2 m / t of silicon-calcium alloy cored wire (Φ14 mm) and 0.6 kg / t of covering agent are added. The outlet temperature is 1637°C.

[0055] (4) Continuous casting: The temperature of the ladle at the station is 1618℃, the amount of molten steel is 98t, the H in the tundish is controlled at 1.6ppm, the whole process is protected casting, and the mold protection slag uses medium carbon steel protection slag.

[0056] (5) Heating process

[0057] Heating process: the temperature entering the heating furnace is 410℃, the temperature of the preheating section is required to be 660℃, and the time is 1.2h; the temperature of the heating section 2 is required to be 860℃, and the time is 1.2h; the temperature of the heating section 1 is required to be 1197℃, and the time is 1.2h, and the average temperature is 1.2h; the temperature of the average heating section is required to be 1195℃, and the time is 1.2h, and the average temperature is 1.8h; the steel tapping temperature is 1180℃.

[0058] (6) Rolling process of product specification Φ60mm:

[0059] Small bar Φ60mm rolling process: the 1st pass is 166mm high and 227mm wide, the 2nd pass is 154mm high and 191mm wide; the 3rd pass is 137mm high and 180mm wide; the 4th pass is 150mm high and 149mm wide; the 5th pass is 98mm high and 172mm wide; the 6th pass is 114mm high and 114mm wide; the 7th pass is 74mm high and 134mm wide; the 8th pass is 88mm high and 88mm wide; the 9th pass is 61mm high and 99mm wide; the 10th pass is 70mm high and 70mm wide; the 11th pass is 54mm high and 76mm wide; the 12th pass is 60mm high and 60mm wide, and the finished product is produced after 12 passes.

[0060] The macrostructure and impact performance test results of the finished product of Example 3 are shown in Tables 1 and 2.

[0061] Table 1 Finished product inspection results - Φ60mm specification macrostructure

[0062] Serial number Generally loose Loose center Ingot segregation General spot segregation Edge spot segregation standard ≤1.5 ≤1.5 ≤1.5 ≤1.0 ≤1.0 Example 1 0.5 0.5 0.5 0 0 Example 2 0.5 0.5 0.5 0 0 Example 3 0.5 0.5 0.5 0 0

[0063] Table 2 Finished product inspection results - Φ60mm specification impact performance

[0064] Serial number First quenching / ℃ Tempering / ℃ Sample specifications <![CDATA[R m / MPa]]> <![CDATA[R el / MPa]]> A / ％ z / ％ <![CDATA[Impact / KU 2 (longitudinal)]]> standard 850, oil cooling 600, water-cooled Φ25 ≥980 ≥785 ≥10 ≥45 ≥63 Example 1 850, oil cooling 600, water-cooled Φ25 1120 815 15 60 70 Example 2 850, oil cooling 600, water-cooled Φ25 1115 830 16 65 75 Example 3 850, oil cooling 600, water-cooled Φ25 1085 825 14 68 78

[0065] For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for producing steel for gear shafts in an ecological electric furnace process, characterized in that: The method comprises the following steps: 100t ECOARC ecological electric furnace + LF + RH + 210mm*210mm continuous casting billet → heating in heating furnace → rolling → heat preservation → finishing → inspection → packaging and storage → delivery; the specification of the produced gear shaft steel 40CrMnMoA bar is Φ60 mm; In the ecological electric furnace smelting process, scrap steel accounts for 100%; the scrap steel loading is 115~120 t, the tapping temperature is 1695℃~1700℃, the C is controlled at 0.15%~0.20% during tapping, P≤0.010%, slag, pre-deoxidizer and ferroalloy are added when 1 / 4~1 / 3 of the steel is tapped, and the tapping amount is 103~107 t; In the LF furnace process, a large current is used to heat up and melt the slag. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime is added; after 5 minutes, the first sampling is taken to analyze the chemical composition, and alloy is added according to the target value of the chemical composition, and carbon is increased; when the molten steel temperature reaches 1555℃~1565℃, 2~3 kg / t of diffusion deoxidizer is added; when the molten steel temperature reaches 1620℃~1630℃, the second sampling is taken for analysis. After the second sample is taken away, the smelting cycle is 60~80 min, and alloy and auxiliary materials are added; In the RH refining process, the inlet temperature is 1670℃~1675℃, the operation time is 28~32 min, and the argon pressure is controlled at 0.1~0.3 MPa before the vacuum pump is started; when the vacuum degree reaches 100 Pa, the timing starts, and the holding time is 10~15 min, and the argon pressure is adjusted to 0.3~0.5 MPa; after the static argon blowing is completed, 2~2.2 m / t of silicon-calcium alloy cored wire and 0.6~0.7kg / t of covering agent are added, and the outlet temperature is 1635℃~1640℃; In the continuous casting process, the temperature of the ladle at the station is 1615℃~1620℃, the amount of molten steel is 95~105 t, the H content of the tundish is controlled to be ≤2 ppm, the whole process is protected casting, and the mold protection slag uses medium carbon steel protection slag; In the heating process, the temperature of the heating furnace is 300℃~540℃, the temperature of the preheating section is 650℃~700℃, and the time is 1.0~1.5 h; the temperature of the second heating section is 840℃~880℃, and the time is 1.0~1.5 h; the temperature of the first heating section is 1190℃~1220℃, and the time is 1.0~1.5 h, and the average temperature is 1.0~1.5 h; the temperature of the equalizing section is 1180℃~1210℃, and the time is 1.0~1.5 h, and the average temperature is 1.5~2 h; the steel tapping temperature is 1170℃~1190℃; In the rolling process, the rolling process of the small bar Φ60mm is as follows: the first pass is 166~166.3 mm high and 227~227.3 mm wide; the second pass is 154~154.3 mm high and 191~191.3 mm wide; the third pass is 137~137.3 mm high and 180~180.3 mm wide; the fourth pass is 150~150.3 mm high and 149~149.3 mm wide; the fifth pass is 98~98.3 mm high and 172~172.3 mm wide; the sixth pass is 114~114.3 mm high and 114~114.3 mm wide; the seventh pass is 74~74.3 mm high and 134~134.3 mm wide; the eighth pass is 88~88.3 mm high and 88~88.3 mm wide; the ninth pass is 61~61.3 high. mm, width 99~99.3 mm; the 10th pass is 70~70.3 mm high, 70~70.3 mm wide; the 11th pass is 54~54.3 mm high, 76~76.3 mm wide; the 12th pass is 60~60.3 mm high, 60~60.3 mm wide, and the finished product is produced after 12 passes; The composition of the molten steel in the continuous casting step of the method is controlled by mass percentage to be C: 0.38%-0.42%, Si: 0.22%-0.35%, Mn: 0.55%-0.70%, P≤0.015%, S≤0.008%, Cr: 0.65%-0.80%, Ni: 1.30%-1.55%, Cu≤0.15%, Mo: 0.16%-0.23%; the remainder is iron and unavoidable impurities.

2. A steel for a gear shaft produced according to the method of claim 1.