Smelting process of q355b steel material

Abstract

The present application relates to a kind of Q355B steel smelting process, belong to metal smelting process, the Q355B steel smelting process can effectively reduce smelting cost, the thickness of smelting Q355B steel ≤6.0mm, cancel the operation of reducing Mn on the basis of original process, cancel Ti microalloying measure, Mn content is reduced about 0.20% than original process, cancel the original process 0.028% Ti microalloying, about 440kg MnSi addition amount is reduced per furnace steel, about 3.2kg / t is reduced per ton steel.Calculation according to the internal MnSi alloy price of steelmaking this month 6.513 yuan / kg, about 20.84 yuan / t is reduced per ton steel cost, cancel FeTi 0.98kg / t alloy addition, reduce Ti microalloying cost 18.2 yuan / t, two total about 39.04 yuan / t is reduced cost, can effectively save cost;The upper yield strength ReH of Q355B steel ≥365~460MPa tensile strength Rm ≥490 MPa transverse elongation A after breaking % ≥20 transverse charpy impact energy ≥27KV2 / J, meet the requirements.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metal smelting, and particularly relates to a smelting process of Q355B steel. BACKGROUND

[0002] The Q355B steel is widely applied in the fields of building engineering, mechanical manufacturing, ship manufacturing, petroleum chemical industry and the like due to its high strength, good toughness, excellent corrosion resistance and good welding performance.

[0003] In the prior art, the smelting of the Q355B steel does not adopt the specification smelting and rolling process, and 20465.54 tons of the Q355B steel is produced in 2-3 months. After the rolling inspection, the strength of some thin specifications of the Q355B steel is too high, 75.0% of the upper yield value is greater than 410 MPa, and the highest reaches 560 MPa, and the overall strength is too high. The reason is that the Mn content in the steelmaking composition is too high, and the Als and Ti micro-alloying strengthening in the steel causes the high strength of the thin specifications. SUMMARY

[0004] In order to overcome the problems in the background art, the present application discloses a smelting process of Q355B steel. The smelting process of the Q355B steel can effectively reduce the smelting cost. The thickness of the smelted Q355B steel is less than or equal to 6.0 mm. The Mn reduction operation and the Ti micro-alloying measure are cancelled on the basis of the original process. The Mn content is reduced by about 0.20% than the original process. The Ti micro-alloying of 0.028% in the original process is cancelled. The MnSi addition amount of each furnace steel is reduced by about 440 kg, and the ton steel is reduced by about 3.2 kg / t. According to the internal MnSi alloy price of the steelmaking of 6.513 yuan / kg in the month, the ton steel cost is reduced by about 20.84 yuan / t. The FeTi alloy of 0.98 kg / t is added, and the Ti micro-alloying cost is reduced by 18.2 yuan / t. The total cost is reduced by about 39.04 yuan / t. The cost can be effectively saved. The upper yield strength ReH of the Q355B steel is greater than or equal to 365-460 MPa, the tensile strength Rm is greater than or equal to 490 MPa, the transverse elongation A after breaking is greater than or equal to 20%, and the transverse Charpy impact energy is greater than or equal to 27 KV2 / J. The requirements are met.

[0005] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme:

[0006] The smelting process of the Q355B steel is characterized in that the process route comprises:

[0007] hot metal pretreatment, converter smelting, tapping slag washing, argon blowing treatment, calcium feeding treatment, full protection casting, casting blank cutting, casting blank red inspection, cleaning burrs, hot sending, soaking furnace soaking, high-pressure water descaling, rolling, coiling machine coiling, coiled steel spraying, inspection, and warehousing.

[0008] As preferred: the molten iron pretreatment is to pretreat the molten iron entering the furnace by desulfurization and clean slagging; the treated molten iron contains C: 0.15-0.19%; Si: 0.25-0.40%; Mn: ≤1.0%; S: ≤0.03%; P ≤0.03%, Als: 0.015-0.045%; Cu, Ni, Cr ≤0.30%.

[0009] As preferred: the pretreated molten iron contains Mn: 0.80-0.95%.

[0010] As preferred: the pretreated molten iron contains oxygen concentration <8 ppm, nitrogen concentration ≤60 ppm.

[0011] As preferred: the converter smelting uses a complex blowing converter bottom blowing N2-Ar switching process for smelting.

[0012] As preferred: the tapping slag washing, argon blowing treatment, and calcium wire feeding treatment include the following steps:

[0013] (1) Tapping slag washing: when the converter is tapped into the ladle, slag and lime slag are poured into the ladle through the alloy chute for slag washing;

[0014] (2) Argon blowing treatment: after the molten steel is poured into the ladle, argon is blown into the ladle from the bottom of the ladle, and by controlling the pressure and time of argon blowing, the molten steel is boiled for refining;

[0015] (3) Silicon calcium wire feeding treatment: using a wire feeder to pour silicon calcium wire into the center position of the descending flow of molten steel in the ladle for treatment.

[0016] As preferred: the slag and lime slag include: CaO, SiO2, Al2O3, CaF2, MgO, CaCl2; wherein CaO, SiO2, Al2O3 are basic oxides, and CaF2, MgO, CaCl2 are fluxes.

[0017] As preferred: the full protection casting uses a physical protection method for full protection casting, including: an Al-C long nozzle is used to communicate between the ladle and the tundish, and the long nozzle is inserted into the molten steel in the tundish by 100-120 mm.

[0018] As preferred: the rolling operation uses a 1050 full continuous rolling strip mill for controlled cooling rolling.

[0019] As preferred: the thickness of the rolled steel is ≤6.0 mm.

[0020] The beneficial effects of the present application: the smelting process of the Q355B steel material can effectively reduce the smelting cost, the thickness of the smelted Q355B steel material is less than or equal to 6.0mm, the Mn reduction operation is cancelled on the basis of the original process, the Ti micro-alloying measure is cancelled, the Mn content is reduced by about 0.20% than the original process, the Ti micro-alloying of 0.028% in the original process is cancelled, the MnSi addition amount of each furnace steel is reduced by about 440kg, and the ton steel is reduced by about 3.2kg / t. According to the internal MnSi alloy price of 6.513 yuan / kg in the month, the ton steel reduces the cost of about 20.84 yuan / t, the FeTi alloy of 0.98kg / t is cancelled, the Ti micro-alloying cost is reduced by 18.2 yuan / t, and the total cost is reduced by about 39.04 yuan / t, which can effectively save the cost; the upper yield strength ReH of the Q355B steel material is greater than or equal to 365-460MPa, the tensile strength Rm is greater than or equal to 490MPa, the transverse elongation A after breaking is greater than or equal to 20%, and the transverse charpy impact energy is greater than or equal to 27KV2 / J, which meets the requirements. DETAILED DESCRIPTION

[0021] In order to make the above-mentioned purpose, technical scheme and beneficial effects clearer and more definite, the present application will be specifically described below in combination with examples.

[0022] Example 1:

[0023] The smelting process of the Q355B steel material has the following process route:

[0024] 1) Hot metal pretreatment: the hot metal pretreatment is to pretreat the hot metal entering the furnace by desulfurization and clean the slag; the treated hot metal contains C: 0.15%; Si: 0.25%; Mn: 0.5%; S: 0.01%; P: 0.01%, Als: 0.015%; Cu, Ni, Cr total: 0.10%; the oxygen concentration in the pretreated hot metal is 8ppm, and the nitrogen concentration is 60ppm.

[0025] 2) Converter smelting: the converter smelting uses the switching process of bottom blowing N2-Ar of combined blowing converter to smelt.

[0026] 3) Tapping slag washing + argon blowing treatment + calcium feeding treatment: the tapping slag washing + argon blowing treatment + calcium wire feeding treatment includes the following steps:

[0027] (1) Tapping slag washing: when the converter tapping is in the ladle, the slag and lime slag are poured into the ladle through the alloy chute for slag washing, wherein the slag and lime slag include CaO, SiO2, Al2O3, CaF2, MgO and CaCl2; wherein CaO, SiO2 and Al2O3 are basic oxides, and CaF2, MgO and CaCl2 are fluxes;

[0028] (2) Argon blowing treatment: After the molten steel is poured into the ladle, argon is blown into the ladle from the bottom of the ladle, and by controlling the pressure and time of argon blowing, the molten steel is boiled for refining;

[0029] (3) Silicon-calcium wire feeding treatment: The silicon-calcium wire is fed into the center position of the descending flow of the molten steel in the ladle using a wire feeding machine.

[0030] 4) Full protection casting: Full protection casting uses physical protection method for full protection casting, including: Al-C long nozzle is used to communicate between the ladle and the tundish, and the long nozzle is inserted into the molten steel in the tundish by 100 mm.

[0031] 5) Casting blank cutting, red inspection of casting blank, and cleaning of burrs;

[0032] 6) Hot charging of the casting blank into the soaking furnace for soaking;

[0033] 7) High-pressure water descaling of the casting blank after soaking;

[0034] 8) Rolling: The casting blank is controlled-cooled rolled using a 1050 full continuous rolling strip mill, and the thickness of the rolled steel is ≤6.0 mm.

[0035] 10) Coiling: The rolled steel is coiled using the steel.

[0036] 11) Marking, inspection, and storage: The coiled steel is marked with product number, and after passing the inspection, it is stored for use.

[0037] Example 2:

[0038] The smelting process of Q355B steel is as follows:

[0039] 1) Hot metal pretreatment: The hot metal pretreatment is to pretreat the incoming hot metal by desulfurization and clean the slag; the pretreated hot metal contains C: 0.19%; Si: 0.40%; Mn: 1.0%; S: 0.03%; P: 0.03%, Als: 0.045%; Cu, Ni, Cr total: 0.30%; the oxygen concentration in the pretreated hot metal is 8 ppm, and the nitrogen concentration is 60 ppm.

[0040] 2) Converter smelting: The converter smelting uses a complex blowing converter bottom blowing N2-Ar switching process for smelting.

[0041] 3) Tapping slag washing + argon blowing treatment + calcium feeding treatment: Tapping slag washing + argon blowing treatment + calcium wire feeding treatment includes the following steps:

[0042] (1) Tapping slag washing: when the molten steel is tapped into the ladle, slag and lime slag are poured into the ladle through the alloy chute for slag washing, wherein the slag and lime slag include CaO, SiO2, Al2O3, CaF2, MgO, CaCl2; wherein CaO, SiO2, Al2O3 are basic oxides, and CaF2, MgO, CaCl2 are fluxes;

[0043] (2) Argon blowing treatment: after the molten steel is poured into the ladle, argon is blown into the ladle from the bottom of the ladle, and the molten steel is boiled by controlling the pressure and time of argon blowing;

[0044] (3) Silicon calcium wire feeding treatment: the silicon calcium wire is poured into the center position of the descending flow of the molten steel in the ladle by using a wire feeding machine.

[0045] 4) Full protection casting: the full protection casting uses a physical protection method for full protection casting, including: an Al-C long nozzle is used to communicate between the ladle and the tundish, and the long nozzle is inserted into the molten steel in the tundish by 120 mm.

[0046] 5) Casting blank cutting, red inspection of casting blank, and cleaning of burrs;

[0047] 6) Hot charging of the casting blank into the soaking furnace;

[0048] 7) Descaling of the casting blank after soaking by high-pressure water;

[0049] 8) Rolling: the casting blank is controlled and cooled by using a 1050 full continuous rolling strip mill, and the thickness of the rolled steel is ≤6.0 mm.

[0050] 10) Coiling by the coiling machine: the rolled steel is coiled by using the steel.

[0051] 11) Number spraying, inspection, and storage: the coiled steel is sprayed with product numbers, and is stored for use after inspection.

[0052] Example 3:

[0053] The smelting process of Q355B steel is as follows:

[0054] 1) Hot metal pretreatment: the hot metal pretreatment is to pretreat the incoming hot metal by desulfurization and clean the slag; the treated hot metal contains C: 0.17%, Si: 0.30%, Mn: 0.85%, S: 0.02%, P: 0.02%, Als: 0.03%, Cu, Ni, Cr total: 0.20%; the oxygen concentration in the pretreated hot metal is 8 ppm, and the nitrogen concentration is 60 ppm.

[0055] 2) Converter smelting: the converter smelting uses a complex blowing converter bottom blowing N2-Ar switching process for smelting.

[0056] 3) Slag washing + argon blowing + calcium feeding: The slag washing + argon blowing + calcium feeding process includes the following steps:

[0057] (1) Slag washing: When the steel is tapped from the converter into the ladle, slag and quicklime are fed into the ladle through an alloy chute for slag washing. The slag and quicklime include: CaO, SiO2, Al2O3, CaF2, MgO, and CaCl2; among which CaO, SiO2, and Al2O3 are the basic oxides, and CaF2, MgO, and CaCl2 are the fluxes.

[0058] (2) Argon blowing treatment: After the molten steel is poured into the ladle, argon gas is blown into the ladle from the bottom. By controlling the pressure and time of argon blowing, the molten steel is boiled and refined.

[0059] (3) Feeding silicon-calcium wire: Use a wire feeder to feed the silicon-calcium wire into the center of the downward flow of molten steel in the ladle for processing.

[0060] 4) Fully Protected Casting: Fully protected casting uses physical protection methods, including: connecting the ladle and tundish with Al-C long nozzles, inserting the long nozzles into the molten steel in the tundish 110mm.

[0061] 5) Billet cutting, billet red inspection, and burr removal;

[0062] 6) The hot billet is sent to a soaking furnace for homogenization;

[0063] 7) After homogenization, the billet is descaled using high-pressure water.

[0064] 8) Rolling: The billet is rolled by controlled cooling using a 1050 continuous strip mill, and the thickness of the rolled steel is ≤6.0mm.

[0065] 10) Coiling machine rolls up: using steel to roll up the rolled steel.

[0066] 11) Marking, inspection, and warehousing: After the steel is coiled, it is marked with the product number, inspected and qualified, and then stored for future use.

[0067] Example 4:

[0068] The smelting process for Q355B steel is as follows:

[0069] 1) Hot metal pretreatment: the hot metal pretreatment is a pretreatment of the hot metal entering the furnace by desulfurization and clean slagging; the total amount of the treated hot metal contains C: 0.15%; Si: 0.17%; Mn: 1.0%; S: 0.015%; P: 0.01%, Als: 0.015%; Cu, Ni, Cr total: 0.10%; the oxygen concentration in the pretreated hot metal is 8 ppm, and the nitrogen concentration is 60 ppm.

[0070] 2) Converter smelting: the converter smelting is performed using a combined blowing converter bottom blowing N2-Ar switching process.

[0071] 3) Tapping slag washing + Ar blowing top slag white slag treatment + Ti micro-alloying + feeding silicon calcium wire treatment, which includes the following steps:

[0072] (1) Tapping slag washing: when the converter is tapped into the ladle, slag and white ash slag are poured into the ladle through the alloy chute for slag washing, wherein the slag and white ash slag include: CaO, SiO2, Al2O3, CaF2, MgO, CaCl2; wherein CaO, SiO2, Al2O3 are basic oxides, and CaF2, MgO, CaCl2 are fluxes;

[0073] (2) Argon blowing treatment: after the molten steel is poured into the ladle, argon is blown into the ladle from the bottom of the ladle, and the molten steel is boiled by controlling the pressure and time of argon blowing;

[0074] (3) Ti micro-alloying: adding 0.015% of Ti to the molten steel ladle for micro-alloying treatment of the molten steel;

[0075] (3) Feeding silicon calcium wire treatment: using a wire feeder to pour silicon calcium wire into the center position of the descending flow of molten steel in the ladle for treatment.

[0076] 4) Full protection casting: full protection casting is performed using physical protection method, including: Al-C long nozzle is used to communicate between the ladle and the tundish, and the long nozzle is inserted into the molten steel in the tundish by 100 mm.

[0077] 5) Casting blank cutting, red inspection of casting blank, and cleaning of burrs;

[0078] 6) Hot charging of casting blank into soaking furnace;

[0079] 7) High-pressure water descaling of the soaked casting blank;

[0080] 8) Rolling: using 1050 full continuous rolling strip mill to control the cooling and rolling of the casting blank, and the thickness of the rolled steel is > 6.0 mm.

[0081] 10) Coiling by coiling machine: using steel to coil the rolled steel.

[0082] 11) Spray number, inspection, and storage: after rolling, the steel material is sprayed with product number, and after inspection, it is stored for standby.

[0083] Example 5:

[0084] The smelting process of Q355B steel material is as follows:

[0085] 1) Pretreatment of molten iron: the pretreatment of molten iron is to pretreat the molten iron entering the furnace by desulfurization and clean the slag; the total amount of treated molten iron contains C: 0.19%; Si: 0.40%; Mn: 1.15%; S: 0.025%; P: 0.03%, Als: 0.045%; Ti: 0.035%; Cu, Ni, Cr total: 0.30%; the oxygen concentration in the pretreated molten iron is 8 ppm, and the nitrogen concentration is 60 ppm.

[0086] 2) Converter smelting: the converter smelting uses a complex blowing converter bottom blowing N2-Ar switching process for smelting.

[0087] 3) Tapping slag washing + Ar blowing top slag white slag treatment + Ti micro-alloying + feeding silicon calcium wire treatment including the following steps:

[0088] (1) Tapping slag washing: when the converter is tapped into the ladle, the slag and white ash slag are poured into the ladle through the alloy chute for slag washing, wherein the slag and white ash slag include: CaO, SiO2, Al2O3, CaF2, MgO, CaCl2; wherein CaO, SiO2, Al2O3 are basic oxides, and CaF2, MgO, CaCl2 are fluxes;

[0089] (2) Argon blowing treatment: after the molten steel is poured into the ladle, argon is blown into the ladle from the bottom of the ladle, and by controlling the pressure and time of argon blowing, the molten steel is boiled for refining;

[0090] (3) Ti micro-alloying: adding 0.035% of Ti to the molten steel ladle for micro-alloying treatment of the molten steel;

[0091] (3) Feeding silicon calcium wire treatment: using a wire feeder to pour silicon calcium wire into the center position of the descending flow of molten steel in the ladle for treatment.

[0092] 4) Full protection casting: full protection casting uses physical protection method for full protection casting, including: Al-C long nozzle is used to connect between the ladle and the tundish, and the long nozzle is inserted into the molten steel in the tundish by 120 mm.

[0093] 5) Billet cutting, billet red inspection, and burr cleaning;

[0094] 6) Hot charging of the billet into the soaking furnace for soaking;

[0095] 7) After soaking, the cast blank is descaled by high-pressure water;

[0096] 8) Rolling: The cast blank is controlled-cooled rolled using a 1050 continuous strip rolling mill, and the thickness of the rolled steel is > 6.0 mm.

[0097] 10) Coiling: The rolled steel is coiled using the steel.

[0098] 11) Marking, inspection, and storage: The coiled steel is marked with a product number, and after passing the inspection, it is stored for use.

[0099] The Q355B steel smelted in Examples 1-3 has a thickness of ≤ 6.0 mm, which is Q355B thin steel; the Q355B steel smelted in Examples 4-6 has a thickness of > 6.0 mm, which is Q355B thick steel; the conventional Q355B steel smelting process does not distinguish between the thickness of the 355B steel,

[0100] Example 6:

[0101] The smelting process of the Q355B steel has the following process route:

[0102] 1) Hot metal pretreatment: The pretreatment of the hot metal is to pretreat the hot metal entering the furnace by desulfurization and clean the slag; the treated hot metal contains C: 0.17%; Si: 0.30%; Mn: 0.85%; S: 0.02%; P: 0.02%, Als: 0.03%; Cu, Ni, Cr total: 0.20%; the oxygen concentration in the pretreated hot metal is 8 ppm, and the nitrogen concentration is 60 ppm.

[0103] 2) Converter smelting: The converter smelting uses a complex blowing converter bottom blowing N2-Ar switching process for smelting.

[0104] 3) Tapping slag washing + Ar blowing top slag white slag treatment + Ti micro-alloying + feeding silicon calcium wire treatment, which includes the following steps:

[0105] (1) Tapping slag washing: When the converter is tapped into the ladle, slag and white ash slag are added to the ladle through the alloy chute for slag washing, wherein the slag and white ash slag include: CaO, SiO2, Al2O3, CaF2, MgO, CaCl2; wherein CaO, SiO2, Al2O3 are basic oxides, and CaF2, MgO, CaCl2 are fluxes;

[0106] (2) Argon blowing treatment: After the molten steel is poured into the ladle, argon is blown into the ladle from the bottom of the ladle, and by controlling the pressure and time of argon blowing, the molten steel is boiled for refining;

[0107] (3) Ti micro-alloying: 0.03% of Ti is added to the molten steel ladle for micro-alloying treatment of the molten steel;

[0108] (3) Feeding calcium silicon wire treatment, using a feeding machine to feed calcium silicon wire into the center of the descending flow of molten steel in the ladle for treatment.

[0109] 4) Full protection casting: full protection casting uses physical protection method for full protection casting, including: Al-C long nozzle is used to communicate between the ladle and the tundish, and the long nozzle is inserted into the tundish 110 mm.

[0110] 5) Slab cutting, red inspection of cast slab, and cleaning of burrs;

[0111] 6) Hot charging of cast slab into soaking furnace for soaking;

[0112] 7) High-pressure water descaling of the cast slab after soaking;

[0113] 8) Rolling: using 1050 full continuous rolling strip mill to control cooling rolling of the cast slab, and the thickness of the rolled steel is > 6.0 mm.

[0114] 10) Coiling: using steel to coil the rolled steel.

[0115] 11) Marking, inspection, and storage: after coiling, the steel is marked with product number, and after inspection, it is stored for use.

[0116] In Examples 1-3, the Q355B steel produced by the smelting process has a thickness of ≤6.0 mm, which is Q355B thin steel. In Examples 4-6, the Q355B steel produced by the smelting process has a thickness of > 6.0 mm, which is Q355B thick steel. The Q355B thin steel and the Q355B thick steel are distinguished by smelting process and specification, which can effectively save costs. The addition percentages of C, Si, Mn, S, P, Als, and Ti in the Q355B thin steel and the Q355B thick steel are shown in Table 1:

[0117] Table 1

[0118]

[0119] The smelting process of the Q355B thin gauge just disclosed in Examples 1-3, and the smelting process of the Q355B thick just disclosed in Examples 4-6, to adopt the smelting of different gauges, can effectively save the cost; among them, in the smelting process of the Q355B thin gauge steel, after taking the measures of reducing Mn and canceling Ti micro-alloying, the Mn content is reduced by about 0.20% than the original process, and the Ti micro-alloying of 0.028% in the original process is canceled. The MnSi addition amount of each furnace is reduced by about 440 kg, and the ton steel is reduced by about 3.2 kg / t. According to the internal MnSi alloy price of the steelmaking in the month of 6.513 yuan / kg, the cost of ton steel is reduced by about 20.84 yuan / t, the FeTi alloy of 0.98 kg / t is canceled, the Ti micro-alloying cost is reduced by 18.2 yuan / t, and the total cost is reduced by about 39.04 yuan / t; due to the cancellation of Ti micro-alloying in the smelting process of Q355B thin steel, the fluidity of the molten steel is improved compared with the original process, the opening operation is relatively smooth compared with the original process, the water port, stop flow and non-steady-state operation of taking the sleeve immersion nozzle are reduced, and the quality of the casting blank and the product quality are improved.

[0120] The Q355B thin gauge steel is produced by using the Q355B steel smelting process described in Examples 1-3, and the performance test is performed on the Q355B thin product. According to the performance test data of the Q355B thin steel, the performance is relatively stable, the high-strength phenomenon is reduced, and the performance of other items is also relatively stable; the performance test data of the Q355B thin steel is shown in Table 2.

[0121] Table 2

[0122]

[0123] The Q355B thin gauge steel is produced by using the Q355B steel smelting process described in Examples 1-3, and the performance of the Q355B thin gauge steel is stable.

[0124] Finally, it should be pointed out that the above preferred embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present application.

Claims

1. A smelting process of Q355B steel material, characterized in that, The smelting process comprises: hot metal pretreatment, converter smelting, tapping slag washing, argon blowing treatment, calcium feeding treatment, full protection casting, casting blank cutting, casting blank red detection, cleaning burrs, hot charging, soaking furnace soaking, high-pressure water descaling, rolling, coiling machine coiling, coiled steel spraying number, inspection, warehousing; The hot metal pretreatment is to pretreat the charging hot metal by desulfurization and clean the slag; the weight percentage of the remaining chemical components in the treated hot metal is: C: 0.15-0.19%; Si: 0.25-0.40%; Mn: ≤1.0%; S: ≤0.03%; P ≤0.03%, Als: 0.015-0.045%; Cu, Ni, Cr ≤0.30%; the pretreated hot metal contains Mn: 0.80-0.95%; the oxygen concentration in the pretreated hot metal is <8ppm, and the nitrogen concentration is ≤60ppm; The converter smelting uses a complex blowing converter bottom blowing N2-Ar switching process for smelting; The tapping slag washing, argon blowing treatment and calcium feeding line treatment comprise the following steps: (1) Tapping slag washing: when the converter is tapped into the ladle, the slag and lime slag are poured into the ladle through the alloy chute for slag washing; (2) Argon blowing treatment: after the molten steel is poured into the ladle, argon is blown into the ladle from the bottom of the ladle, and by controlling the pressure and time of argon blowing, the molten steel is boiled for refining; (3) Silicon calcium wire feeding treatment: the silicon calcium wire is poured into the center position of the descending flow of the molten steel in the ladle using a wire feeding machine for treatment; The slag and lime slag comprise: CaO, SiO2, Al2O3, CaF2, MgO, CaCl2; wherein CaO, SiO2, Al2O3 are basic oxides, and CaF2, MgO, CaCl2 are fluxes.

2. The smelting process of the Q355B steel material according to claim 1, characterized in that: The full protection casting uses a physical protection method for full protection casting, which comprises: an Al-C long nozzle is used to communicate between the ladle and the tundish, and the long nozzle is inserted into the molten steel in the tundish by 100-120mm.

3. The smelting process of the Q355B steel material according to claim 1, characterized in that: The rolling operation uses a 1050 full continuous rolling strip mill for controlled cooling rolling.

4. The smelting process of the Q355B steel material according to claim 3, characterized in that: The thickness of the rolled steel is ≤6.0mm.

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