Steel bar for automobile compressor rotor and production and preparation method of steel bar

Abstract

The invention discloses a steel bar for an automobile compressor rotor and a production and preparation method of the steel bar. The steel bar is prepared from, by mass, 0.31%-0.36% of C, 0.20%-0.35% of Si, 0.42%-0.60% of Mn, smaller than or equal to 0.015% of P, smaller than or equal to 0.010% of S, 1.02%-1.20% of Cr, smaller than or equal to 0.25% of Ni, 0.21%-0.28% of Mo, 0.11%-0.18% of V, smaller than or equal to 0.15% of Cu and the balance iron and inevitable impurities. The process route comprises electric furnace smelting, LF furnace refining, VD refining, continuous casting, heating furnace heating, rolling and heat preservation. The steel bar for the automobile compressor rotor is produced through the electric furnace + LF + RH + continuous casting smelting process and the rolling process, the production specification is phi 120 mm, the mechanical property requirement is met, and the steel purity is guaranteed; the mechanical property and the impact property are ensured by reasonable component design and production process; the macrostructure, non-metallic inclusions and mechanical properties of the finished steel meet the requirements of high-end products.

Description

Technical Field

[0001] The invention relates to a steel bar material for an automobile compressor rotor and a production method thereof, and belongs to the field of steelmaking. Background Art

[0002] As the core of the automobile refrigeration system, the automobile compressor adopts a closed structure and does not require the addition of lubricants. It can be adjusted and controlled according to the real-time changing operating requirements such as vehicle speed, room temperature and refrigeration load. As the main part of the automobile compressor, the automobile compressor rotor is required to have good wear resistance, tensile strength and temperature resistance. In addition, it should also have good fatigue resistance, impact resistance and vibration resistance to ensure the normal operation of the automobile compressor. As an important part of the refrigeration device, the automobile compressor rotor has strict quality requirements.

[0003] The quality of the steel bars used in automobile compressor rotors directly affects the service life and wear resistance of the refrigeration device, and even affects the safety of the entire refrigeration device working process.

[0004] The electric furnace + LF + VD + continuous casting smelting process and rolling process are used to produce steel bars for automobile compressor rotors, which meet high-end usage requirements and achieve a breakthrough in the mass production of steel bars for automobile compressor rotors using the electric furnace continuous casting process. Summary of the invention

[0005] The purpose of the present invention is to provide a production process and preparation method for steel bars for automobile compressor rotors. The method adopts electric furnace + LF + VD + continuous casting smelting process to produce steel bars for automobile compressor rotors, which not only ensures the mechanical properties, impact properties and high steel purity of the finished steel bars for automobile compressor rotors, but also ensures the surface quality level of the steel bars for automobile compressor rotors.

[0006] In order to achieve the above invention purpose, the present invention provides a composition design and process design of steel bars for automobile compressor rotors, with specific steps: electric furnace smelting + LF furnace refining + VD refining + continuous casting → heating furnace heating → rolling → insulation. It meets the quality requirements of steel bars for automobile compressor rotors, and the indicators such as mechanical properties, impact properties and high steel purity can also meet the standard requirements.

[0007] The present invention provides a steel bar material for automobile compressor rotors, which comprises the following components by mass percentage:

[0008] C: 0.31% ~ 0.36%, Si: 0.20% ~ 0.35%, Mn: 0.42% ~ 0.60%, P: ≤0.015%, S: ≤0.010%, Cr: 1.02% ~ 1.20%, Ni: ≤0.25%, Mo: 0.21% ~ 0.28%, V: 0.11% ~ 0.18%, Cu: ≤0.15%, the balance is iron and unavoidable impurities.

[0009] The present invention provides a method for preparing the above-mentioned steel bar for automobile compressor rotors, and the process route is: electric furnace smelting + LF furnace refining + VD refining + continuous casting → heating in a heating furnace → rolling → insulation → finishing → inspection → packaging and storage → delivery.

[0010] The electric furnace smelting is as follows: using 60% to 65% molten iron and 35% to 40% scrap steel for smelting; oxygen oxidation, intense boiling, automatic slag flow, full melting temperature of 1590 to 1600°C, tapping temperature of 1675 to 1685°C, C of 0.03 to 0.08% at tapping time, P≤0.010%, adding slag, pre-deoxidizer, and ferroalloy when 1 / 4 to 1 / 3 of the steel is tapped. The amount of alloy added per ton of steel: 1.2 to 1.3 kg / t of aluminum iron, 4 to 4.1 kg / t of high carbon ferromanganese, and 14 to 15 kg / t of high carbon ferrochrome. Amount of auxiliary materials added per ton of steel: alumina balls 4-4.1Kg / t, coke powder recarburizer 0.6-0.7Kg / t, electric furnace foaming agent 2.6-2.7Kg / t, tapping port filler 1.0-1.1Kg / t, active lime 32-33Kg / t.

[0011] The LF furnace refining is as follows: adopting 20000-25000A high current to heat up and melt slag, refining time is 70-75min, reaching LF position temperature of 1518-1625℃, when the slag surface fluctuates, molten steel and arc are not exposed, add active lime, take the first sample to analyze the chemical composition after 4-6min, add alloy according to the target value of chemical composition, and increase carbon, alloy and carbon powder should be added to the argon gas flow to promote the rapid melting and homogenization of alloy and carbon powder. When the temperature of molten steel reaches 1550-1560℃, add diffusion deoxidizer to carry out diffusion deoxidation, when the temperature of molten steel reaches 1600-1610℃, take the second sample to analyze the chemical composition to confirm the deviation value of the content of each chemical element from the target value, after the second sample is taken away, add diffusion deoxidizer to continue slag adjustment, the hanging bag temperature is 1675-1685℃. Add alloy: high carbon ferromanganese 1.8~1.9kg / t, high carbon ferrochrome 1.4~1.5kg / t, ferromolybdenum 3.5~3.6kg / t, ferrovanadium 2.2~2.3kg / t, aluminum wire 2.4~2.5m / t, ferrosilicon powder 3.6~3.7kg / t. Auxiliary materials: active lime 9~9.5kg / t, carbide slag 1.2~1.3kg / t, alumina ball 1.0~1.1kg / t, fluorite briquette 1.0~1.1kg / t, coke powder recarburizer 0.3~0.35kg / t. At the same time, continue to maintain white slag smelting for 20~30min. LF post-slag sample basicity requirements: binary basicity ensures R1≥10, ternary basicity R2≥12, quaternary basicity R3≥1.5.

[0012] The VD refining is as follows: the temperature before entering the VD is 1670℃~1675℃, the argon pressure is controlled at 0.1~0.3MPa before the vacuum pump is started, the free space is 850~860mm, the molten steel is not exposed when the slag surface is slightly moved, the timing starts when the vacuum degree reaches 95~100Pa, the holding time is 15~20min, the vacuum breaking temperature is 1600℃~1610℃, the alloy is added according to the composition of the molten steel, and the argon pressure is adjusted to 0.3~0.5MPa at the same time, the static argon blowing time is 25~30min, after the static argon blowing is finished, Φ10~Φ12mm calcium silicon cored wire 2.0~2.1m / t is added, and the hanging bag temperature is 1570℃~1578℃. Auxiliary materials: carbonized rice husk 0.7~0.8kg / t.

[0013] Furthermore, in the above technical scheme, the continuous casting is: the ladle arrival temperature is 1560-1570°C, the H in the tundish is controlled ≤2ppm, the temperature in the tundish is 1524-1527°C, the pulling speed is 0.83-0.85m / min, the whole process is protected casting, and the crystallizer protective slag uses medium carbon steel protective slag.

[0014] Furthermore, in the above technical scheme, the heating process is: the temperature entering the heating furnace is 350℃~500℃, the temperature of the preheating section is required to be 650℃~700℃, and the time is 1.0~1.2h; the temperature of the heating section 2 is required to be 840℃~860℃, and the time is 1.0~1.2h; the temperature of the heating section 1 is required to be 1190℃~1220℃, and the time is 1.2~1.5h; the temperature of the soaking section is required to be 1180℃~1210℃, and the time is 1.0~1.2h; the steel tapping temperature is 1170℃~1190℃.

[0015] Furthermore, in the above technical solution, the rolling includes a continuous casting slab BD cogging process and a continuous rolling process.

[0016] BD billet opening process for continuous casting: rolling 3 times, rolling reduction: steel turning → 1st pass high 263~263.1mm, width 239~239.1mm, roll gap 103~103.1mm, reduction 7~7.1mm; → 2nd pass high 263~263.1mm, width 239~239.1mm, roll gap 103~103.1mm, reduction 0mm; → steel turning → 3rd pass high 233~233.1mm, width 265~265.1mm, roll gap 73~73.1mm, reduction 6~6.1mm, passing through 3 850mm rolling mills, 1 735mm rolling mill, and then entering 8 continuous rolling mills for rolling.

[0017] Continuous rolling process: 9 passes, the first pass is 229-229.1mm high, 245-245.1mm wide, 53-53.1mm roll gap, and 0.27-0.28m / s; the second pass is 192-192.1mm high, 235-235.1mm wide, 16-16.1mm roll gap, and 0.31-0.32m / s; the third pass is 200-200.1mm high mm, width 195~195.1mm, roll gap 24~24.1mm, rolling speed 0.35~0.351m / s; the 4th pass is 160~160.1mm high, 214.7~214.8mm wide, roll gap 10~10.1mm, rolling speed 0.474~0.475m / s; the 5th pass is 168~168.1mm high, 174.6~174.7mm wide, roll gap 12~ 12.1mm, rolling speed 0.598~0.599m / s; 6th pass height 120~120.1mm, width 187.6~187.7mm, roll gap 14~14.1mm, rolling speed 0.743~0.744m / s; 7th pass height 142~142.1mm, width 138.5~138.6mm, roll gap 22~22.1mm, rolling speed 0.934~0.9 35m / s; the 8th pass is 111~111.1mm high, 151.5~151.6mm wide, 17~17.1mm roll gap, and rolling speed 1.102~1.103m / s; the 9th pass is 122.04~122.05mm high, 122.04~122.05mm wide, 7.4~7.5mm roll gap, and rolling speed 1.217~1.218m / s; the finished product is produced after 9 passes.

[0018] Furthermore, in the above technical solution, the insulation process is: steel insulation, lower insulation pit temperature ≥ 600°C, insulation 48 to 55 hours, pit exit temperature ≤ 150°C.

[0019] Furthermore, in the above technical solution, the steel after insulation is subjected to heat treatment, and the heat treatment comprises the following steps:

[0020] 1) First quenching: 880-920℃, keep warm for 0.8-1.0h, oil cooling;

[0021] 2) Tempering: 620-640℃, keep warm for 1.8-2.2h, air cooling.

[0022] Advantageous Effects of the Invention

[0023] (1) The electric furnace + LF + RH + continuous casting smelting process and rolling process are used to produce steel bars for automobile compressor rotors. The production specification is Φ120mm, which meets the mechanical property requirements and ensures the purity of the steel.

[0024] (2) Reasonable component design and production process ensure mechanical properties and impact properties.

[0025] (3) The macrostructure, non-metallic inclusions and mechanical properties of the finished steel meet the requirements of high-end products. DETAILED DESCRIPTION

[0026] Embodiment 1:

[0027] 1Chemical composition of steel bars for automobile compressor rotors

[0028] The internal controlled chemical composition determined by mass percentage is C: 0.33%, Si: 0.25%, Mn: 0.49%, P: 0.010%, S: 0.005%, Cr: 1.09%, Ni: 0.02%, Mo: 0.25%, V: 0.15%, Cu: 0.02%, and the balance is iron and unavoidable impurities.

[0029] 2. The electric furnace continuous casting production process of steel bars for automobile compressor rotors includes the following steps:

[0030] Process route: electric furnace + LF + VD + continuous casting billet → heating in heating furnace → rolling → insulation → finishing → inspection → packaging and storage → delivery.

[0031] (1) Electric furnace smelting

[0032] Use 64% molten iron and 36% scrap steel for smelting; oxygen oxidation, intense boiling, automatic slag flow, full melting temperature 1595℃, tapping temperature 1680℃, C is 0.04% and P is 0.008% when tapping, and add auxiliary materials and alloys when 1 / 4 of the steel is tapped. The amount of alloy added per ton of steel: 1.2Kg / t of aluminum iron, 4Kg / t of high carbon ferromanganese, and 14.5Kg / t of high carbon ferrochrome. The amount of auxiliary materials added per ton of steel: 4Kg / t of alumina balls (pre-deoxidizer), 0.6Kg / t of coke powder recarburizer (pre-deoxidizer), 2.67Kg / t of electric furnace foaming agent (slag), 1.0Kg / t of tapping port filler (slag), and 32.4Kg / t of active lime (slag).

[0033] (2) LF furnace refining

[0034] A high current of 22000A is used to heat up the slag, and the refining time is 72 minutes. The temperature reaches 1520℃ at the LF position. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime, carbide slag and fluorite briquette are added. After 5 minutes, the chemical composition is analyzed for the first time. The alloy is added according to the target value of the chemical composition, and coke powder is added to increase carbon. The alloy and coke powder should be added to the argon flow to promote the rapid melting and homogenization of the alloy and carbon powder. When the temperature of the molten steel reaches 1555℃, a diffusion deoxidizer alumina balls are added for diffusion deoxidation. When the temperature of the molten steel reaches 1605℃, 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, a diffusion deoxidizer alumina balls are added to continue slag adjustment, and the ladle temperature is 1679℃. At the same time, the white slag smelting is continued for 25 minutes. Alkalinity requirements for slag samples after LF: binary alkalinity guarantee R1: 10.5, ternary alkalinity R2: 12.4, quaternary alkalinity R3: 1.6.

[0035] In this step, the amount of the above substances added is: additional alloy: high carbon ferromanganese 1.8kg / t, high carbon ferrochrome 1.4kg / t, ferromolybdenum 3.5kg / t, ferrovanadium 2.2kg / t, aluminum wire 2.4m / t, ferrosilicon powder 3.6kg / t. Auxiliary materials: active lime 9.2kg / t, carbide slag 1.2kg / t, alumina balls 1.0kg / t, fluorite briquette 1.0kg / t, coke powder recarburizer 0.33kg / t.

[0036] (3) VD refining

[0037] The temperature before entering VD is 1672℃. Before the vacuum pump is started, the argon pressure is controlled at 0.2MPa. The free space is 854mm. The molten steel is not exposed when the slag surface moves slightly. When the vacuum degree reaches 100Pa, the timing starts. The holding time is 17min. The vacuum breaking temperature is 1603℃. The molten steel sample is taken for chemical composition analysis. According to the target value of chemical composition, alloy (high carbon ferromanganese, high carbon ferrochromium, ferromolybdenum, ferrovanadium) and auxiliary materials are added. At the same time, the argon pressure is adjusted to 0.4MPa. The static argon blowing time is 26min. After the static argon blowing is completed, Φ10mm calcium silicon cored wire 2.0m / t is added. The hanging bag temperature is 1575℃. Auxiliary materials: carbonized rice husk 0.7kg / t.

[0038] (4) Continuous casting

[0039] The temperature of the ladle at the station for continuous casting is 1564℃, the H of the tundish is controlled at 1.3ppm, the temperature of the tundish is 1525℃, the casting speed is 0.84m / min, the whole process is protected casting, and the crystallizer protection slag uses medium carbon steel protection slag.

[0040] (5) Heating process

[0041] The heating process in chronological order is: the temperature entering the heating furnace is 450℃, the temperature of the preheating section is required to be 660℃, and the time is 1.1h; the temperature of the heating section 2 is required to be 850℃, and the time is 1.0h; the temperature of the heating section 1 is required to be 1200℃, and the time is 1.3h; the temperature of the soaking section is required to be 1200℃, and the time is 1.0h; the steel tapping temperature is 1180℃.

[0042] (6) Rolling process

[0043] BD billet opening process for continuous casting billet: 1150mm BD primary rolling mill is used for billet opening, and 3 rolling passes are performed with rolling reduction: steel turning → 1st pass high 263mm, width 239mm, roll gap 103mm, reduction 7mm; → 2nd pass high 263mm, width 239mm, roll gap 103mm, reduction 0mm; → steel turning → 3rd pass high 233mm, width 265mm, roll gap 73mm, reduction 6mm, passing through 3 850mm rolling mills, 1 735mm rolling mill, and then entering the 8-stand continuous rolling mill group for rolling.

[0044] Continuous rolling 9-pass rolling process: the first pass is 229mm high, 245mm wide, 53mm roll gap, and 0.27m / s; the second pass is 192mm high, 235mm wide, 16mm roll gap, and 0.31m / s; the third pass is 200mm high, 195mm wide, 24mm roll gap, and 0.35m / s; the fourth pass is 160mm high, 214.7mm wide, 10mm roll gap, and 0.474m / s; the fifth pass is 168mm high, 174.6mm wide, and 12m roll gap m, rolling speed 0.598m / s; the 6th pass is 120mm high, 187.6mm wide, 14mm roll gap, and 0.743m / s; the 7th pass is 142mm high, 138.5mm wide, 22mm roll gap, and 0.934m / s; the 8th pass is 111mm high, 151.5mm wide, 17mm roll gap, and 1.102m / s; the 9th pass is 122.04mm high, 122.04mm wide, 7.4mm roll gap, and 1.217m / s; the finished product is produced after 9 passes.

[0045] (7) Insulation process

[0046] Insulation process: Steel insulation, lower insulation pit temperature 620℃, insulation 52h, exit pit temperature 120℃.

[0047] (8) Heat treatment

[0048] The steel after heat preservation is heat treated, and the heat treatment includes the following steps:

[0049] 1) First quenching: 900℃, holding time 0.9h, oil cooling;

[0050] 2) Tempering: 630℃, keep warm for 2h, air cool.

[0051] Embodiment 2:

[0052] 1Chemical composition of steel bars for automobile compressor rotors

[0053] In percentage by mass, the components are C: 0.34%, Si: 0.24%, Mn: 0.48%, P: 0.009%, S: 0.004%, Cr: 1.06%, Ni: 0.03%, Mo: 0.25%, V: 0.14%, Cu: 0.02%, and the balance is iron and inevitable impurities.

[0054] 2. The electric furnace continuous casting production process of steel bars for automobile compressor rotors includes the following steps:

[0055] Process route: electric furnace + LF + VD + continuous casting billet → heating in heating furnace → rolling → insulation → finishing → inspection → packaging and storage → delivery.

[0056] (1) Electric furnace smelting

[0057] The smelting process uses 62% molten iron and 38% scrap steel; oxygen oxidation, intense boiling, automatic slag flow, full melting temperature of 1594℃, tapping temperature of 1680℃, C of 0.04% and P of 0.007% during tapping, and auxiliary materials and alloys are added when 1 / 4 of the steel is tapped. The amount of alloy added per ton of steel: 1.2Kg / t of aluminum iron, 4Kg / t of high carbon ferromanganese, and 14.4Kg / t of high carbon ferrochrome. The amount of auxiliary materials added per ton of steel: 4Kg / t of alumina balls (pre-deoxidizer), 0.6Kg / t of coke powder recarburizer (pre-deoxidizer), 2.6Kg / t of electric furnace foaming agent (slag), 1.0Kg / t of tapping port filler (slag), and 32.6Kg / t of active lime (slag).

[0058] (2) LF furnace refining

[0059] A high current of 22000A is used to heat up the slag, and the refining time is 72 minutes. The temperature reaches 1521℃ at the LF position. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime, carbide slag and fluorite briquette are added. After 5 minutes, the chemical composition is analyzed for the first time. The alloy is added according to the target value of the chemical composition, and coke powder is added to increase carbon. The alloy and coke powder should be added to the argon flow to promote the rapid melting and homogenization of the alloy and carbon powder. When the temperature of the molten steel reaches 1556℃, the diffusion deoxidizer alumina balls are added for diffusion deoxidation. When the temperature of the molten steel reaches 1604℃, 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 diffusion deoxidizer alumina balls are added to continue to adjust the slag, and the hanging bag temperature is 1679℃. At the same time, the white slag smelting is continued for 26 minutes. Alkalinity requirements for slag samples after LF: binary alkalinity guarantee R1: 10.5, ternary alkalinity R2: 12.6, quaternary alkalinity R3: 1.7.

[0060] In this step, the amount of the above substances added is: additional alloy: high carbon ferromanganese 1.8kg / t, high carbon ferrochrome 1.4kg / t, ferromolybdenum 3.5kg / t, ferrovanadium 2.2kg / t, aluminum wire 2.4m / t, ferrosilicon powder 3.6kg / t. Auxiliary materials: active lime 9.3kg / t, carbide slag 1.2kg / t, alumina balls 1.0kg / t, fluorite briquette 1.0kg / t, coke powder recarburizer 0.34kg / t.

[0061] (3) VD refining

[0062] The temperature before entering VD is 1672℃. Before the vacuum pump is started, the argon pressure is controlled at 0.2MPa. The free space is 854mm. The molten steel is not exposed when the slag surface moves slightly. When the vacuum degree reaches 100Pa, the timing starts. The holding time is 17min. The vacuum breaking temperature is 1605℃. The chemical composition of the molten steel is analyzed by sampling. According to the target value of the chemical composition, alloy (high carbon ferromanganese, high carbon ferrochromium, ferromolybdenum, ferrovanadium) and auxiliary materials are added. At the same time, the argon pressure is adjusted to 0.4MPa. The static argon blowing time is 28min. After the static argon blowing is completed, Φ10mm calcium silicon cored wire 2.0m / t is added. The hanging bag temperature is 1575℃. Auxiliary materials: carbonized rice husk 0.7kg / t.

[0063] (4) Continuous casting

[0064] The temperature of the ladle at the station for continuous casting is 1564℃, the H of the tundish is controlled at 1.4ppm, the temperature of the tundish is 1525℃, the casting speed is 0.83m / min, the whole process is protected casting, and the crystallizer protection slag uses medium carbon steel protection slag.

[0065] (5) Heating process

[0066] The heating process in chronological order is: the temperature entering the heating furnace is 420℃, the temperature of the preheating section is required to be 660℃, and the time is 1.1h; the temperature of the heating section 2 is required to be 850℃, and the time is 1.1h; the temperature of the heating section 1 is required to be 1210℃, and the time is 1.2h; the temperature of the soaking section is required to be 1205℃, and the time is 1.1h; the steel tapping temperature is 1180℃.

[0067] (6) Rolling process

[0068] BD billet opening process for continuous casting billet: 1150mm BD primary rolling mill is used for billet opening, and rolling is performed for 3 passes with rolling reduction: steel turning → 1st pass: 263mm high, 239mm wide, 103mm roll gap, 7mm reduction; → 2nd pass: 263mm high, 239mm wide, 103mm roll gap, 0mm reduction; → steel turning → 3rd pass: 233mm high, 265mm wide, 73mm roll gap, 6mm reduction, passing through 3 850mm rolling mills, 1 735mm rolling mill, and then entering 8-stand continuous rolling mill group for rolling.

[0069] Continuous rolling 9-pass rolling process: the first pass is 229mm high, 245mm wide, 53mm roll gap, and 0.27m / s; the second pass is 192mm high, 235mm wide, 16mm roll gap, and 0.31m / s; the third pass is 200mm high, 195mm wide, 24mm roll gap, and 0.35m / s; the fourth pass is 160mm high, 214.7mm wide, 10mm roll gap, and 0.474m / s; the fifth pass is 168mm high, 174.6mm wide, and 12m roll gap m, rolling speed 0.598m / s; the 6th pass is 120mm high, 187.6mm wide, 14mm roll gap, and 0.743m / s; the 7th pass is 142mm high, 138.5mm wide, 22mm roll gap, and 0.934m / s; the 8th pass is 111mm high, 151.5mm wide, 17mm roll gap, and 1.102m / s; the 9th pass is 122.04mm high, 122.04mm wide, 7.45mm roll gap, and 1.217m / s; the finished product is produced after 9 passes.

[0070] (7) Insulation process

[0071] Insulation process: Steel insulation, lower insulation pit temperature 610℃, insulation 53h, exit pit temperature 110℃.

[0072] (8) Heat treatment

[0073] The steel after heat preservation is heat treated, and the heat treatment includes the following steps:

[0074] 1) First quenching: 900℃, holding time 0.9h, oil cooling;

[0075] 2) Tempering: 630℃, keep warm for 2h, air cool.

[0076] Embodiment 3:

[0077] 1Chemical composition of steel bars for automobile compressor rotors

[0078] In percentage by mass, the components are C: 0.34%, Si: 0.25%, Mn: 0.48%, P: 0.010%, S: 0.004%, Cr: 1.08%, Ni: 0.03%, Mo: 0.24%, V: 0.15%, Cu: 0.03%, and the balance is iron and inevitable impurities.

[0079] 2. The electric furnace continuous casting production process of steel bars for automobile compressor rotors includes the following steps:

[0080] Process route: electric furnace + LF + VD + continuous casting billet → heating in heating furnace → rolling → insulation → finishing → inspection → packaging and storage → delivery.

[0081] (1) Electric furnace smelting

[0082] 64% molten iron and 36% scrap steel are used for smelting; oxygen oxidation, intense boiling, automatic slag flow, full melting temperature of 1595℃, tapping temperature of 1681℃, C of 0.06% and P of 0.008% at tapping time, and auxiliary materials and alloys are added when 1 / 4 of the steel is tapped. The amount of alloy added per ton of steel: 1.2Kg / t of aluminum iron, 4Kg / t of high carbon ferromanganese, and 14.5g / t of high carbon ferrochrome. The amount of auxiliary materials added per ton of steel: 4Kg / t of alumina balls (as pre-deoxidizer), 0.64Kg / t of coke powder recarburizer (as pre-deoxidizer), 2.6Kg / t of electric furnace foaming agent (as slag), 1.0Kg / t of tapping port filler (as slag), and 32.5Kg / t of active lime (as slag).

[0083] (2) LF furnace refining

[0084] A high current of 21000A is used to heat up the slag, and the refining time is 72 minutes. The temperature at the LF position is 1622℃. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime, carbide slag and fluorite briquette are added. After 5 minutes, the chemical composition is analyzed for the first time. The alloy is added according to the target value of the chemical composition, and coke powder is added to increase carbon. The alloy and coke powder should be added to the argon flow to promote the rapid melting and homogenization of the alloy and carbon powder. When the temperature of the molten steel reaches 1556℃, a diffusion deoxidizer alumina balls are added for diffusion deoxidation. When the temperature of the molten steel reaches 1605℃, 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, a diffusion deoxidizer alumina balls are added to continue slag adjustment, and the ladle temperature is 1681℃. At the same time, the white slag smelting is continued for 26 minutes. Alkalinity requirements for slag samples after LF: binary alkalinity guarantee R1: 10.6, ternary alkalinity R2: 12.6, quaternary alkalinity R3: 1.7.

[0085] In this step, the amount of the above substances added is: additional alloy: high carbon ferromanganese 1.8kg / t, high carbon ferrochrome 1.4kg / t, ferromolybdenum 3.5kg / t, ferrovanadium 2.2kg / t, aluminum wire 2.4m / t, ferrosilicon powder 3.6kg / t. Auxiliary materials: active lime 9.3kg / t, carbide slag 1.2kg / t, alumina balls 1.0kg / t, fluorite briquette 1.0kg / t, coke powder recarburizer 0.32kg / t.

[0086] (3) VD refining

[0087] The temperature before entering VD is 1672℃. Before the vacuum pump is started, the argon pressure is controlled at 0.1MPa. The free space is 855mm. The molten steel is not exposed when the slag surface moves slightly. When the vacuum degree reaches 100Pa, the timing starts. The holding time is 18min. The vacuum breaking temperature is 1606℃. The molten steel sample is taken for chemical composition analysis. According to the target value of chemical composition, alloy (high carbon ferromanganese, high carbon ferrochromium, ferromolybdenum, ferrovanadium) and auxiliary materials are added. At the same time, the argon pressure is adjusted to 0.4MPa. The static argon blowing time is 27min. After the static argon blowing is completed, Φ10mm calcium silicon cored wire 2.0m / t is added. The hanging bag temperature is 1575℃. Auxiliary materials: carbonized rice husk 0.7kg / t.

[0088] (4) Continuous casting

[0089] The temperature of the ladle at the station for continuous casting is 1565℃, the H of the tundish is controlled at 1.3ppm, the temperature of the tundish is 1525℃, the casting speed is 0.83m / min, the whole process is protected casting, and the crystallizer protection slag uses medium carbon steel protection slag.

[0090] (5) Heating process

[0091] The heating process in chronological order is: the temperature entering the heating furnace is 440℃, the temperature of the preheating section is required to be 680℃, and the time is 1.0h; the temperature of the heating section 2 is required to be 850℃, and the time is 1.0h; the temperature of the heating section 1 is required to be 1205℃, and the time is 1.3h; the temperature of the soaking section is required to be 1206℃, and the time is 1.1h; the steel tapping temperature is 1180℃.

[0092] (6) Rolling process

[0093] BD billet opening process for continuous casting billet: 1150mm BD primary rolling mill is used for billet opening, and rolling is performed for 3 passes with rolling reduction: steel turning → 1st pass: 263mm high, 239mm wide, 103mm roll gap, 7mm reduction; → 2nd pass: 263mm high, 239mm wide, 103mm roll gap, 0mm reduction; → steel turning → 3rd pass: 233mm high, 265mm wide, 73mm roll gap, 6mm reduction, passing through 3 850mm rolling mills, 1 735mm rolling mill, and then entering 8-stand continuous rolling mill group for rolling.

[0094] Continuous rolling 9-pass rolling process: the first pass is 229mm high, 245mm wide, 53mm roll gap, and 0.27m / s; the second pass is 192mm high, 235mm wide, 16mm roll gap, and 0.31m / s; the third pass is 200mm high, 195mm wide, 24mm roll gap, and 0.35m / s; the fourth pass is 160mm high, 214.7mm wide, 10mm roll gap, and 0.474m / s; the fifth pass is 168mm high, 174.6mm wide, and 12m roll gap m, rolling speed 0.598m / s; the 6th pass is 120mm high, 187.6mm wide, 14mm roll gap, and 0.743m / s; the 7th pass is 142mm high, 138.5mm wide, 22mm roll gap, and 0.934m / s; the 8th pass is 111mm high, 151.5mm wide, 17mm roll gap, and 1.102m / s; the 9th pass is 122.045mm high, 122.04mm wide, 7.4mm roll gap, and 1.217m / s; the finished product is produced after 9 passes.

[0095] (7) Insulation process

[0096] Insulation process: Steel insulation, lower insulation pit temperature 610℃, insulation 52h, exit pit temperature 110℃.

[0097] (8) Heat treatment

[0098] The steel after heat preservation is heat treated, and the heat treatment includes the following steps:

[0099] 1) First quenching: 900℃, holding time 0.9h, oil cooling;

[0100] 2) Tempering: 630℃, keep warm for 2h, air cool.

[0101] Embodiment 4:

[0102] 1Chemical composition of steel bars for automobile compressor rotors

[0103] In terms of mass percentage, C: 0.34%, Si: 0.25%, Mn: 0.48%, P: 0.010%, S: 0.004%, Cr: 1.08%, Ni: 0.03%, Mo: 0.25%, V: 0.14%, and Cu: 0.03%.

[0104] 2. The electric furnace continuous casting production process of steel bars for automobile compressor rotors includes the following steps:

[0105] Process route: electric furnace + LF + VD + continuous casting billet → heating in heating furnace → rolling → insulation → finishing → inspection → packaging and storage → delivery.

[0106] (1) Electric furnace smelting

[0107] The smelting process uses 63% molten iron and 37% scrap steel; oxygen oxidation, intense boiling, automatic slag flow, full melting temperature of 1596℃, tapping temperature of 1681℃, C of 0.05% and P of 0.008% during tapping, and auxiliary materials and alloys are added when 1 / 4 of the steel is tapped. The amount of alloy added per ton of steel: 1.2Kg / t of aluminum iron, 4Kg / t of high carbon ferromanganese, and 14.6Kg / t of high carbon ferrochrome. The amount of auxiliary materials added per ton of steel: 4Kg / t of alumina balls (pre-deoxidizer), 0.6Kg / t of coke powder recarburizer (pre-deoxidizer), 2.6Kg / t of electric furnace foaming agent (slag), 1.0Kg / t of tapping port filler (slag), and 32.4Kg / t of active lime (slag).

[0108] (2) LF furnace refining

[0109] A high current of 21000A is used to heat up the slag, and the refining time is 72 minutes. The temperature reaches 1622℃ at the LF position. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime, carbide slag and fluorite briquette are added. After 5 minutes, the chemical composition is analyzed for the first time. The alloy is added according to the target value of the chemical composition, and coke powder is added to increase carbon. The alloy and coke powder should be added to the argon flow to promote the rapid melting and homogenization of the alloy and carbon powder. When the temperature of the molten steel reaches 1554℃, a diffusion deoxidizer alumina balls are added for diffusion deoxidation. When the temperature of the molten steel reaches 1605℃, 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, a diffusion deoxidizer alumina balls are added to continue slag adjustment, and the ladle temperature is 1680℃. At the same time, the white slag smelting is continued for 25 minutes. Alkalinity requirements for slag samples after LF: binary alkalinity guarantee R1: 10.3, ternary alkalinity R2: 12.6, quaternary alkalinity R3: 1.7.

[0110] In this step, the amount of the above substances added is: additional alloy: high carbon ferromanganese 1.8kg / t, high carbon ferrochrome 1.4kg / t, ferromolybdenum 3.5kg / t, ferrovanadium 2.2kg / t, aluminum wire 2.4m / t, ferrosilicon powder 3.6kg / t. Auxiliary materials: active lime 9.2kg / t, carbide slag 1.2kg / t, alumina balls 1.0kg / t, fluorite briquette 1.0kg / t, coke powder recarburizer 0.3kg / t.

[0111] (3) VD refining

[0112] The temperature before entering VD is 1672℃. Before the vacuum pump is started, the argon pressure is controlled at 0.1MPa. The free space is 854mm. The molten steel is not exposed when the slag surface moves slightly. When the vacuum degree reaches 100Pa, the timing starts and the holding time is 17min. The vacuum breaking temperature is 1604℃. The molten steel sample is taken for chemical composition analysis. According to the target value of chemical composition, alloy (high carbon ferromanganese, high carbon ferrochromium, ferromolybdenum, ferrovanadium) and auxiliary materials are added. At the same time, the argon pressure is adjusted to 0.3MPa. The static argon blowing time is 27min.

[0113] After the static argon blowing is completed, 2.0m / t of Φ10mm calcium silicon cored wire is added, and the bag temperature is 1573℃. Auxiliary materials: 0.7kg / t of carbonized rice husk.

[0114] (4) Continuous casting

[0115] The temperature of the ladle at the station for continuous casting is 1564℃, the H of the tundish is controlled at 1.2ppm, the temperature of the tundish is 1525℃, the casting speed is 0.83m / min, the whole process is protected casting, and the crystallizer protection slag uses medium carbon steel protection slag.

[0116] (5) Heating process

[0117] The heating process in chronological order is: the temperature entering the heating furnace is 460℃, the temperature of the preheating section is required to be 680℃, and the time is 1.0h; the temperature of the heating section 2 is required to be 850℃, and the time is 1.1h; the temperature of the heating section 1 is required to be 1210℃, and the time is 1.3h; the temperature of the soaking section is required to be 1200℃, and the time is 1.1h; the steel tapping temperature is 1183℃.

[0118] (6) Rolling process

[0119] BD billet opening process for continuous casting billet: 1150mm BD primary rolling mill is used for billet opening, and rolling is performed for 3 passes with rolling reduction: steel turning → 1st pass: 263mm high, 239mm wide, 103mm roll gap, 7mm reduction; → 2nd pass: 263mm high, 239mm wide, 103mm roll gap, 0mm reduction; → steel turning → 3rd pass: 233mm high, 265mm wide, 73mm roll gap, 6mm reduction, passing through 3 850mm rolling mills, 1 735mm rolling mill, and then entering 8-stand continuous rolling mill group for rolling.

[0120] Continuous rolling 9-pass rolling process: the first pass is 229mm high, 245mm wide, 53mm roll gap, and 0.27m / s; the second pass is 192mm high, 235mm wide, 16mm roll gap, and 0.31m / s; the third pass is 200mm high, 195mm wide, 24mm roll gap, and 0.35m / s; the fourth pass is 160mm high, 214.7mm wide, 10mm roll gap, and 0.474m / s; the fifth pass is 168mm high, 174.6mm wide, and 12m roll gap m, rolling speed 0.598m / s; the 6th pass is 120mm high, 187.6mm wide, 14mm roll gap, and 0.743m / s; the 7th pass is 142mm high, 138.5mm wide, 22mm roll gap, and 0.934m / s; the 8th pass is 111mm high, 151.5mm wide, 17mm roll gap, and 1.102m / sn; the 9th pass is 122.04mm high, 122.04mm wide, 7.4mm roll gap, and 1.217m / s; the finished product is produced after 9 passes.

[0121] (7) Insulation process

[0122] Insulation process: Steel insulation, lower insulation pit temperature 620℃, insulation 51h, exit pit temperature 120℃.

[0123] (8) Heat treatment

[0124] The steel after heat preservation is heat treated, and the heat treatment includes the following steps:

[0125] 1) First quenching: 900℃, holding time 0.9h, oil cooling;

[0126] 2) Tempering: 630℃, keep warm for 2h, air cool.

[0127] Embodiment 5:

[0128] 1Chemical composition of steel bars for automobile compressor rotors

[0129] In percentage by mass, the components are C: 0.33%, Si: 0.26%, Mn: 0.48%, P: 0.010%, S: 0.005%, Cr: 1.08%, Ni: 0.03%, Mo: 0.25%, V: 0.15%, Cu: 0.04%, and the balance is iron and inevitable impurities.

[0130] 2. The electric furnace continuous casting production process of steel bars for automobile compressor rotors includes the following steps:

[0131] Process route: electric furnace + LF + VD + continuous casting billet → heating in heating furnace → rolling → insulation → finishing → inspection → packaging and storage → delivery.

[0132] (1) Electric furnace smelting

[0133] The smelting process uses 62% molten iron and 38% scrap steel; oxygen oxidation, intense boiling, automatic slag flow, full melting temperature of 1595℃, tapping temperature of 1680℃, C of 0.05% and P of 0.009% during tapping, and auxiliary materials and alloys are added when 1 / 4 of the steel is tapped. The amount of alloy added per ton of steel: 1.2Kg / t of aluminum iron, 4Kg / t of high carbon ferromanganese, and 14.6Kg / t of high carbon ferrochrome. The amount of auxiliary materials added per ton of steel: 4Kg / t of alumina balls (pre-deoxidizer), 0.6Kg / t of coke powder recarburizer (pre-deoxidizer), 2.6Kg / t of electric furnace foaming agent (slag), 1.0Kg / t of tapping port filler (slag), and 32.5Kg / t of active lime (slag).

[0134] (2) LF furnace refining

[0135] A high current of 22000A is used to heat up the slag, and the refining time is 72 minutes. The temperature reaches 1622℃ at the LF position. When the slag surface fluctuates and the molten steel and arc are not exposed, active lime, carbide slag and fluorite briquette are added. After 5 minutes, the chemical composition is analyzed for the first time. The alloy is added according to the target value of the chemical composition, and coke powder is added to increase carbon. The alloy and coke powder should be added to the argon flow to promote the rapid melting and homogenization of the alloy and carbon powder. When the temperature of the molten steel reaches 1556℃, a diffusion deoxidizer alumina balls are added for diffusion deoxidation. When the temperature of the molten steel reaches 1604℃, 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, a diffusion deoxidizer alumina balls are added to continue slag adjustment, and the ladle temperature is 1682℃. At the same time, the white slag smelting is continued for 25 minutes. Alkalinity requirements for slag samples after LF: binary alkalinity guarantee R1: 10.5, ternary alkalinity R2: 12.4, quaternary alkalinity R3: 1.6.

[0136] In this step, the amount of the above substances added is: additional alloy: high carbon ferromanganese 1.8kg / t, high carbon ferrochrome 1.4kg / t, ferromolybdenum 3.5kg / t, ferrovanadium 2.2kg / t, aluminum wire 2.4m / t, ferrosilicon powder 3.6kg / t. Auxiliary materials: active lime 9.1kg / t, carbide slag 1.2kg / t, alumina balls 1.0kg / t, fluorite briquette 1.0kg / t, coke powder recarburizer 0.32kg / t.

[0137] (3) VD refining

[0138] The temperature before entering VD is 1672℃. Before the vacuum pump is started, the argon pressure is controlled at 0.1MPa. The free space is 854mm. The molten steel is not exposed when the slag surface moves slightly. When the vacuum degree reaches 100Pa, the timing starts and the holding time is 17min. The vacuum breaking temperature is 1605℃. The molten steel sample is taken for chemical composition analysis. According to the target value of chemical composition, alloy (high carbon ferromanganese, high carbon ferrochromium, ferromolybdenum, ferrovanadium) and auxiliary materials are added. At the same time, the argon pressure is adjusted to 0.3MPa. The static argon blowing time is 27min.

[0139] After the static argon blowing is completed, add Φ10mm calcium silicon cored wire 2.0m / t, and the bag temperature is 1574℃. Auxiliary materials: carbonized rice husk 0.7kg / t.

[0140] (4) Continuous casting

[0141] The temperature of the ladle at the station for continuous casting is 1565℃, the H of the tundish is controlled at 1.2ppm, the temperature of the tundish is 1525℃, the casting speed is 0.84m / min, the whole process is protected casting, and the crystallizer protection slag uses medium carbon steel protection slag.

[0142] (5) Heating process

[0143] The heating process in chronological order is: the temperature entering the heating furnace is 450℃, the temperature of the preheating section is required to be 670℃, and the time is 1.1h; the temperature of the heating section 2 is required to be 850℃, and the time is 1.1h; the temperature of the heating section 1 is required to be 1210℃, and the time is 1.3h; the temperature of the soaking section is required to be 1195℃, and the time is 1.1h; the steel tapping temperature is 1180℃.

[0144] (6) Rolling process

[0145] BD billet opening process for continuous casting billet: 1150mm BD primary rolling mill is used for billet opening, and rolling is performed for 3 passes with rolling reduction: steel turning → 1st pass: 263mm high, 239mm wide, 103mm roll gap, 7mm reduction; → 2nd pass: 263mm high, 239mm wide, 103mm roll gap, 0mm reduction; → steel turning → 3rd pass: 233mm high, 265mm wide, 73mm roll gap, 6mm reduction, passing through 3 850mm rolling mills, 1 735mm rolling mill, and then entering 8-stand continuous rolling mill group for rolling.

[0146] Continuous rolling 9-pass rolling process: the first pass is 229mm high, 245mm wide, 53mm roll gap, and 0.27m / s; the second pass is 192mm high, 235mm wide, 16mm roll gap, and 0.31m / s; the third pass is 200mm high, 195mm wide, 24mm roll gap, and 0.35m / s; the fourth pass is 160mm high, 214.7mm wide, 10mm roll gap, and 0.474m / s; the fifth pass is 168mm high, 174.6mm wide, and 12m roll gap m, rolling speed 0.598m / s; the 6th pass is 120mm high, 187.6mm wide, 14mm roll gap, and 0.743m / s; the 7th pass is 142mm high, 138.5mm wide, 22mm roll gap, and 0.934m / s; the 8th pass is 111mm high, 151.5mm wide, 17mm roll gap, and 1.102m / s; the 9th pass is 122.04mm high, 122.04mm wide, 7.44mm roll gap, and 1.217m / s; the finished product is produced after 9 passes.

[0147] (7) Insulation process

[0148] Insulation process: Steel insulation, lower insulation pit temperature 610℃, insulation 52h, exit pit temperature 120℃.

[0149] (8) Heat treatment

[0150] The steel after heat preservation is heat treated, and the heat treatment includes the following steps:

[0151] 1) First quenching: 900℃, holding time 0.9h, oil cooling;

[0152] 2) Tempering: 630℃, keep warm for 2h, air cool.

[0153] 2. Test results of finished products of Examples 1 to 5, 2 samples were tested for each heat of steel

[0154] (1) Φ120mm specification macrostructure (finished steel obtained by heat preservation process)

[0155]

[0156]

[0157] (2) Φ120mm non-metallic inclusions (finished steel obtained by thermal insulation process)

[0158]

[0159] (3) Mechanical properties of Φ120mm specification (finished steel after heat treatment)

[0160]

Claims

1. A steel bar for automobile compressor rotor, characterized in that: The percentage by mass is: C: 0.31% ~ 0.36%, Si: 0.20% ~ 0.35%, Mn: 0.42% ~ 0.60%, P: ≤0.015%, S: ≤0.010%, Cr: 1.02% ~ 1.20%, Ni: ≤0.25%, Mo: 0.21% ~ 0.28%, V: 0.11% ~ 0.18%, Cu: ≤0.15%, the balance is iron and unavoidable impurities.

2. A method for preparing a steel bar for an automobile compressor rotor according to claim 1, characterized in that: The steps include: The process route is: electric furnace smelting + LF furnace refining + VD refining + continuous casting → heating in heating furnace → rolling → insulation; The electric furnace smelting is as follows: using 60wt% to 65wt% molten iron and 35wt% to 40wt% scrap steel for smelting; oxygen oxidation, intense boiling, automatic slag flow, full melting temperature of 1590 to 1600°C, steel tapping temperature of 1675 to 1685°C, C of 0.03 to 0.08wt% when tapping, P≤0.010wt%, and adding auxiliary materials and alloys when 1 / 4 to 1 / 3 of the steel is tapped; The LF furnace refining is as follows: using a large current of 20000-25000A to heat and melt the slag, the refining time is 70-75min, the LF position temperature reaches 1518-1625°C, when the slag surface fluctuates and the molten steel and the arc are not exposed, active lime, carbide slag and fluorite briquette are added, 4-6min later, the first sampling is performed to analyze the chemical composition, and the alloy is added according to the target value of the chemical composition, and the coke powder recarburizer powder should be added to the argon gas flow to promote the rapid melting and homogenization of the alloy and the coke powder; when the molten steel temperature reaches 1550-1560 ℃, add diffusion deoxidizer alumina balls for diffusion deoxidation. When the molten steel temperature reaches 1600-1610℃, take a second sample to analyze the chemical composition to confirm the deviation of the content of each chemical element from the target value. After the second sample is taken, add diffusion deoxidizer alumina balls to continue slag adjustment. The ladle temperature is 1675-1685℃; at the same time, continue to maintain white slag smelting for 20-30min; the basicity requirements of slag samples after LF: binary basicity R1≥10, ternary basicity R2≥12, quaternary basicity R3≥1.5; The VD refining is as follows: the temperature before entering the VD is 1670°C-1675°C, the argon pressure is controlled at 0.1-0.3MPa before the vacuum pump is started, the free space is 850-860mm, the molten steel is not exposed when the slag surface moves slightly, the timing starts when the vacuum degree reaches 95-100Pa, the holding time is 15-20min, the vacuum breaking temperature is 1600°C-1610°C, the molten steel sample is taken for chemical composition analysis, alloy and auxiliary materials are added according to the target chemical composition value, the argon pressure is adjusted to 0.3-0.5MPa, the static argon blowing time is 25-30min, after the static argon blowing is completed, 2.0-2.1m / t of Φ10-Φ12mm silicon calcium cored wire is added, and the hanging bag temperature is 1570°C-1578°C; auxiliary material: 0.7-0.8kg / t of carbonized rice husk.

3. The preparation method according to claim 2, characterized in that: In the electric furnace smelting, the amount of alloy added per ton of steel is: 1.2-1.3 Kg / t of aluminum iron, 4-4.1 Kg / t of high carbon ferromanganese, and 14-15 Kg / t of high carbon ferrochrome; the amount of auxiliary materials added per ton of steel is: 4-4.1 Kg / t of alumina balls, 0.6-0.7 Kg / t of coke powder recarburizer, 2.6-2.7 Kg / t of electric furnace foaming agent, 1.0-1.1 Kg / t of tapping port filler, and 32-33 Kg / t of active lime.

4. The preparation method according to claim 2, characterized in that: During the LF furnace refining, the alloy input is: 1.8-1.9 kg / t high carbon ferromanganese, 1.4-1.5 kg / t high carbon ferrochrome, 3.5-3.6 kg / t ferromolybdenum, 2.2-2.3 kg / t ferrovanadium, 2.4-2.5 m / t aluminum wire, 3.6-3.7 kg / t ferrosilicon powder; the auxiliary material input is: 9-9.5 kg / t active lime, 1.2-1.3 kg / t calcium carbide slag, 1.0-1.1 kg / t alumina balls, 1.0-1.1 kg / t fluorite briquette, 0.3-0.35 kg / t coke powder recarburizer.

5. The preparation method according to claim 2, characterized in that: The continuous casting is as follows: the continuous casting of the ladle at the arrival station temperature is 1560-1570°C, the H of the tundish is controlled to be ≤2ppm, the temperature of the tundish is 1524-1527°C, the casting speed is 0.83-0.85m / min, the whole process is protected casting, and the crystallizer protection slag uses medium carbon steel protection slag.

6. The preparation method according to claim 2, characterized in that: The heating process in chronological order is: the temperature entering the heating furnace is 350℃~500℃, the temperature of the preheating section is required to be 650℃~700℃, and the time is 1.0~1.2h; the temperature of the heating section 2 is required to be 840℃~860℃, and the time is 1.0~1.2h; the temperature of the heating section 1 is required to be 1190℃~1220℃, and the time is 1.2~1.5h; the temperature of the soaking section is required to be 1180℃~1210℃, and the time is 1.0~1.2h; the steel tapping temperature is 1170℃~1190℃.

7. The preparation method according to claim 2, characterized in that: The rolling process includes a continuous casting BD billet opening process and a continuous rolling process; BD billet opening process for continuous casting billet: the billet is opened by the primary rolling mill, and rolled for 3 passes with rolling reduction: steel turning → the first pass is 263-263.1mm high, 239-239.1mm wide, 103-103.1mm roll gap, and 7-7.1mm reduction; → the second pass is 263-263.1mm high, 239-239.1mm wide, 103-103.1mm roll gap, and 0mm reduction; → steel turning → the third pass is 233-233.1mm high, 265-265.1mm wide, 73-73.1mm roll gap, and 6-6.1mm reduction, passing through 3 850mm rolling mills, 1 735mm rolling mill, and then entering the 8-stand continuous rolling mill group for rolling.

8. The preparation method according to claim 5, characterized in that: Continuous rolling process: 9 passes, the first pass is 229-229.1mm high, 245-245.1mm wide, 53-53.1mm roll gap, and 0.27-0.28m / s; the second pass is 192-192.1mm high, 235-235.1mm wide, 16-16.1mm roll gap, and 0.31-0.32m / s; the third pass is 200-200.1mm high mm, width 195~195.1mm, roll gap 24~24.1mm, rolling speed 0.35~0.351m / s; the 4th pass is 160~160.1mm high, 214.7~214.8mm wide, roll gap 10~10.1mm, rolling speed 0.474~0.475m / s; the 5th pass is 168~168.1mm high, 174.6~174.7mm wide, roll gap 12~ 12.1mm, rolling speed 0.598~0.599m / s; 6th pass height 120~120.1mm, width 187.6~187.7mm, roll gap 14~14.1mm, rolling speed 0.743~0.744m / s; 7th pass height 142~142.1mm, width 138.5~138.6mm, roll gap 22~22.1mm, rolling speed 0.934~0.9 35m / s; the 8th pass is 111~111.1mm high, 151.5~151.6mm wide, 17~17.1mm roll gap, and rolling speed 1.102~1.103m / s; the 9th pass is 122.04~122.05mm high, 122.04~122.05mm wide, 7.4~7.5mm roll gap, and rolling speed 1.217~1.218m / s; the finished product is produced after 9 passes.

9. The preparation method according to claim 2, characterized in that: The insulation process is as follows: steel insulation, lower insulation pit temperature ≥ 600°C, insulation for 48 to 55 hours, and pit exit temperature ≤ 150°C.

10. The preparation method according to claim 2, characterized in that: The steel after heat preservation is heat treated, and the heat treatment includes the following steps: 1) First quenching: 880-920℃, keep warm for 0.8-1.0h, oil cooling; 2) Tempering: 620-640℃, keep warm for 1.8-2.2h, air cooling.

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