Smelting process of Q355B steel

Abstract

The invention relates to a smelting process of Q355B steel, and belongs to a metal smelting process, 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 microalloying measure are canceled on the basis of the original process, the Mn content is reduced by about 0.20% compared with the original process, the microalloying of 0.028% Ti contained in the original process is canceled, and the quality of the Q355B steel is improved. And the addition amount of MnSi is reduced by about 440 kg per furnace of steel, and the addition amount of MnSi per ton of steel is reduced by about 3.2 kg / t. According to the fact that the price of MnSi alloy in steelmaking in the current month is 6.513 yuan / kg, the cost of each ton of steel is reduced by about 20.84 yuan / t, 0.98 kg / t of FeTi alloy is omitted, the cost of Ti microalloying is reduced by 18.2 yuan / t, the total cost of the two items is reduced by about 39.04 yuan / t, and the cost can be effectively saved; the upper yield strength ReH of the Q355B steel is larger than or equal to 365-460 MPa, the tensile strength Rm is larger than or equal to 490 MPa, the transverse percentage elongation after fracture A / % is larger than or equal to 20, and the transverse Charpy impact energy is larger than or equal to 27 KV2 / J, and the requirements are met.

Description

Technical Field

[0001] The invention belongs to metal smelting technology, and specifically relates to a smelting technology of Q355B steel. Background Art

[0002] Q355B steel is widely used in construction engineering, machinery manufacturing, shipbuilding, petrochemical industry and other fields due to its high strength, good toughness, excellent corrosion resistance and good welding performance; In the prior art, the smelting of Q355B steel did not adopt the specification-based smelting and rolling process. 20,465.54 tons were produced from February to March. After rolling inspection, it was found that the strength of some thin-sized Q355B was too high, of which 75.0% had an upper yield value greater than 410MPa, and the highest reached 560MPa, and the overall strength was too high. The reason was that the Mn content in the steelmaking composition was too high, and at the same time, due to the strengthening effect of Als and Ti micro-alloying in the steel, the strength of the thin specifications was higher. Summary of the invention

[0003] In order to overcome the problems existing in the background technology, the present invention discloses a smelting process of Q355B steel. The smelting process of Q355B steel can effectively reduce the smelting cost. The thickness of the smelted Q355B steel is ≤6.0mm. On the basis of the original process, the Mn reduction operation and the Ti microalloying measure are cancelled. The Mn content is reduced by about 0.20% compared with the original process, and the Ti microalloying containing 0.028% in the original process is cancelled. The MnSi addition amount per furnace of steel is reduced by about 440kg, and the steel weight is reduced by about 3.2kg / t. Calculated based on the internal steelmaking MnSi alloy price of 6.513 yuan / kg in that month, the cost per ton of steel was reduced by about 20.84 yuan / t, the FeTi 0.98kg / t alloy addition was cancelled, and the Ti microalloying cost was reduced by 18.2 yuan / t. The two items reduced the cost by about 39.04 yuan / t in total, which can effectively save costs. The upper yield strength ReH ≥ 365 ~ 460MPa of Q355B steel, the tensile strength Rm ≥ 490 MPa, the transverse elongation after fracture A / % ≥ 20, and the transverse Charpy impact energy ≥ 27KV2 / J meet the requirements.

[0004] To achieve the above object, the present invention is implemented through the following technical solutions: The smelting process of the Q355B steel is characterized in that the process route includes: Hot metal pretreatment, converter smelting, slag washing, argon blowing, calcium feeding, full-protection casting, ingot cutting, ingot red inspection, burr cleaning, hot delivery, soaking in a soaking furnace, high-pressure water descaling, rolling, coiling on a coiler, number spraying of coiled steel, inspection, and warehousing.

[0005] Preferably, the molten iron pretreatment is to pre-treat the molten iron into the furnace with desulfurization and remove the slag; the molten iron after treatment 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%.

[0006] Preferably, the pretreated molten iron contains 0.80-0.95% Mn.

[0007] Preferably, the oxygen concentration in the pretreated molten iron is less than 8 ppm, and the nitrogen concentration is less than or equal to 60 ppm.

[0008] Preferably, the converter smelting is carried out using a combined blowing converter bottom blowing N2-Ar switching process.

[0009] Preferably, the slag washing, argon blowing and calcium line feeding treatment include the following steps: (1) Slag washing: When the steel is tapped from the converter into the ladle, slag and lime slag are added into the ladle through the alloy chute for slag washing; (2) Argon blowing treatment: After the molten steel is discharged into the ladle, argon gas is blown into the ladle from the bottom of the ladle. By controlling the pressure and time of argon blowing, the molten steel is boiled and refined; (3) Silicon-calcium wire feeding treatment: use a wire feeding machine to feed the silicon-calcium wire into the center of the downward flow of molten steel in the ladle for treatment.

[0010] Preferably, the slag and white ash slag include: CaO, SiO2, Al2O3, CaF2, MgO, CaCl2; wherein CaO, SiO2, Al2O3 are used as basic oxides, and CaF2, MgO, CaCl2 are used as fluxes.

[0011] Preferably, the full protection casting is performed by a physical protection method, including: the ladle and the tundish are connected by an Al-C long shroud, and the long shroud is inserted into the molten steel in the tundish by 100-120 mm.

[0012] Preferably, the rolling operation uses a 1050 fully continuous strip mill for controlled cold rolling.

[0013] Preferably, the thickness of the steel after rolling is ≤6.0 mm.

[0014] The beneficial effects of the present invention are as follows: the smelting process of the Q355B steel can effectively reduce the smelting cost, the thickness of the smelted Q355B steel is ≤6.0 mm, the Mn reduction operation is cancelled on the basis of the original process, the Ti microalloying measure is cancelled, the Mn content is reduced by about 0.20% compared with the original process, the 0.028% Ti microalloying in the original process is cancelled, the MnSi addition amount is reduced by about 440 kg per furnace of steel, and the steel weight is reduced by about 3.2 kg / t. Calculated based on the internal steelmaking MnSi alloy price of 6.513 yuan / kg in that month, the cost per ton of steel was reduced by about 20.84 yuan / t, the FeTi 0.98kg / t alloy addition was cancelled, and the Ti microalloying cost was reduced by 18.2 yuan / t. The two items reduced the cost by about 39.04 yuan / t in total, which can effectively save costs. The upper yield strength ReH ≥ 365 ~ 460MPa of Q355B steel, the tensile strength Rm ≥ 490 MPa, the transverse elongation after fracture A / % ≥ 20, and the transverse Charpy impact energy ≥ 27KV2 / J meet the requirements. DETAILED DESCRIPTION

[0015] In order to make the above-mentioned purpose, technical scheme and beneficial effects clearer and more specific, the present invention is specifically described below in conjunction with embodiments.

[0016] Embodiment 1: The smelting process of Q355B steel is as follows: 1) Hot metal pretreatment: Hot metal pretreatment is to desulfurize the hot metal and remove the slag. The hot metal after treatment 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 hot metal after pretreatment is 8ppm, and the nitrogen concentration is 60ppm.

[0017] 2) Converter smelting: Converter smelting uses the combined blowing converter bottom blowing N2-Ar switching process for smelting.

[0018] 3) Slag washing + argon blowing + calcium feeding: Slag washing + argon blowing + calcium feeding line treatment includes the following steps: (1) Slag washing: When steel is tapped from the converter into the ladle, slag and lime slag are added 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 used as basic oxides, and CaF2, MgO, CaCl2 are used as fluxes; (2) Argon blowing treatment: After the molten steel is discharged into the ladle, argon gas is blown into the ladle from the bottom of the ladle. By controlling the pressure and time of argon blowing, the molten steel is boiled and refined; (3) Silicon-calcium wire feeding treatment: use a wire feeding machine to feed the silicon-calcium wire into the center of the downward flow of molten steel in the ladle for treatment.

[0019] 4) Full protection casting: Full protection casting uses physical protection method for full protection casting, including: the ladle and the tundish are connected by an Al-C long shroud, and the long shroud is inserted into the molten steel in the tundish by 100mm.

[0020] 5) Cutting of ingot, inspection of ingot redness, and cleaning of burrs; 6) The hot ingot is sent to the soaking furnace for soaking; 7) After soaking, the ingot is descaled by high-pressure water; 8) Rolling: Use 1050 full continuous strip rolling mill to carry out controlled cold rolling of the ingot, and the thickness of the steel after rolling is ≤6.0mm.

[0021] 10) Coiler: Coil the rolled steel using the steel coiler.

[0022] 11) Numbering, inspection, and storage: The steel products are sprayed with product numbers after coiling, and are stored for standby after passing the inspection.

[0023] Embodiment 2: The smelting process of Q355B steel is as follows: 1) Hot metal pretreatment: Hot metal pretreatment is to pre-treat the hot metal entering the furnace through desulfurization and slag removal; the hot metal after treatment 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 of the hot metal after pretreatment is 8ppm, and the nitrogen concentration is 60ppm.

[0024] 2) Converter smelting: Converter smelting uses the combined blowing converter bottom blowing N2-Ar switching process for smelting.

[0025] 3) Slag washing + argon blowing + calcium feeding: Slag washing + argon blowing + calcium feeding line treatment includes the following steps: (1) Slag washing: When steel is tapped from the converter into the ladle, slag and lime slag are added 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 used as basic oxides, and CaF2, MgO, CaCl2 are used as fluxes; (2) Argon blowing treatment: After the molten steel is discharged into the ladle, argon gas is blown into the ladle from the bottom of the ladle. By controlling the pressure and time of argon blowing, the molten steel is boiled and refined; (3) Silicon-calcium wire feeding treatment: use a wire feeding machine to feed the silicon-calcium wire into the center of the downward flow of molten steel in the ladle for treatment.

[0026] 4) Full protection casting: Full protection casting uses physical protection method for full protection casting, including: the ladle and the tundish are connected by an Al-C long shroud, and the long shroud is inserted into the molten steel in the tundish by 120mm.

[0027] 5) Cutting of ingot, inspection of ingot redness, and cleaning of burrs; 6) The hot ingot is sent to the soaking furnace for soaking; 7) After soaking, the ingot is descaled by high-pressure water; 8) Rolling: Use 1050 full continuous strip rolling mill to carry out controlled cold rolling of the ingot, and the thickness of the steel after rolling is ≤6.0mm.

[0028] 10) Coiler: Coil the rolled steel using the steel coiler.

[0029] 11) Numbering, inspection, and storage: The steel products are sprayed with product numbers after coiling, and are stored for standby after passing the inspection.

[0030] Embodiment 3: The smelting process of Q355B steel is as follows: 1) Hot metal pretreatment: Hot metal pretreatment is to desulfurize the hot metal and remove the slag. The hot metal after treatment 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 of the hot metal after pretreatment is 8ppm, and the nitrogen concentration is 60ppm.

[0031] 2) Converter smelting: Converter smelting uses the combined blowing converter bottom blowing N2-Ar switching process for smelting.

[0032] 3) Slag washing + argon blowing + calcium feeding: Slag washing + argon blowing + calcium feeding line treatment includes the following steps: (1) Slag washing: When steel is tapped from the converter into the ladle, slag and lime slag are added 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 used as basic oxides, and CaF2, MgO, CaCl2 are used as fluxes; (2) Argon blowing treatment: After the molten steel is discharged into the ladle, argon gas is blown into the ladle from the bottom of the ladle. By controlling the pressure and time of argon blowing, the molten steel is boiled and refined; (3) Silicon-calcium wire feeding treatment: use a wire feeding machine to feed the silicon-calcium wire into the center of the downward flow of molten steel in the ladle for treatment.

[0033] 4) Full protection casting: Full protection casting uses physical protection method for full protection casting, including: the ladle and the tundish are connected by an Al-C long shroud, and the long shroud is inserted into the molten steel in the tundish 110mm.

[0034] 5) Cutting of ingot, inspection of ingot redness, and cleaning of burrs; 6) The hot ingot is sent to the soaking furnace for soaking; 7) After soaking, the ingot is descaled by high-pressure water; 8) Rolling: Use 1050 full continuous strip rolling mill to carry out controlled cold rolling of the ingot, and the thickness of the steel after rolling is ≤6.0mm.

[0035] 10) Coiler: Coil the rolled steel using the steel coiler.

[0036] 11) Numbering, inspection, and storage: The steel products are sprayed with product numbers after coiling, and are stored for standby after passing the inspection.

[0037] Embodiment 4: The smelting process of Q355B steel is as follows: 1) Hot metal pretreatment: Hot metal pretreatment is to pre-treat the hot metal into the furnace with desulfurization and remove the slag; the total amount of hot metal after treatment 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 pre-treated hot metal is 8ppm, and the nitrogen concentration is 60ppm.

[0038] 2) Converter smelting: Converter smelting uses the combined blowing converter bottom blowing N2-Ar switching process for smelting.

[0039] 3) Slag washing + Ar blowing of top slag white slag treatment + Ti microalloying + silicon calcium wire feeding treatment includes the following steps: (1) Slag washing: When steel is tapped from the converter into the ladle, slag and lime slag are added 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 used as basic oxides, and CaF2, MgO, CaCl2 are used as fluxes; (2) Argon blowing treatment: After the molten steel is discharged into the ladle, argon gas is blown into the ladle from the bottom of the ladle. By controlling the pressure and time of argon blowing, the molten steel is boiled and refined; (3) Ti microalloying: adding 0.015% Ti to the ladle to microalloy the molten steel; (3) Silicon-calcium wire feeding treatment: use a wire feeding machine to feed the silicon-calcium wire into the center of the downward flow of molten steel in the ladle for treatment.

[0040] 4) Full protection casting: Full protection casting uses physical protection method for full protection casting, including: the ladle and the tundish are connected by an Al-C long shroud, and the long shroud is inserted into the molten steel in the tundish by 100mm.

[0041] 5) Cutting of ingot, inspection of ingot redness, and cleaning of burrs; 6) The hot ingot is sent to the soaking furnace for soaking; 7) After soaking, the ingot is descaled by high-pressure water; 8) Rolling: Use 1050 full continuous strip rolling mill to carry out controlled cold rolling on the ingot, and the thickness of the steel after rolling is greater than 6.0mm.

[0042] 10) Coiler: Coil the rolled steel using the steel coiler.

[0043] 11) Numbering, inspection, and storage: The steel products are sprayed with product numbers after coiling, and are stored for standby after passing the inspection.

[0044] Embodiment 5: The smelting process of Q355B steel is as follows: 1) Hot metal pretreatment: Hot metal pretreatment is to pre-treat the hot metal entering the furnace through desulfurization and slag removal; the total amount of hot metal after treatment 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 of the hot metal after pretreatment is 8ppm, and the nitrogen concentration is 60ppm.

[0045] 2) Converter smelting: Converter smelting uses the combined blowing converter bottom blowing N2-Ar switching process for smelting.

[0046] 3) Slag washing + Ar blowing of top slag white slag treatment + Ti microalloying + silicon calcium wire feeding treatment includes the following steps: (1) Slag washing: When steel is tapped from the converter into the ladle, slag and lime slag are added 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 used as basic oxides, and CaF2, MgO, CaCl2 are used as fluxes; (2) Argon blowing treatment: After the molten steel is discharged into the ladle, argon gas is blown into the ladle from the bottom of the ladle. By controlling the pressure and time of argon blowing, the molten steel is boiled and refined; (3) Ti microalloying: Add 0.035% Ti to the ladle to microalloy the molten steel; (3) Silicon-calcium wire feeding treatment: use a wire feeding machine to feed the silicon-calcium wire into the center of the downward flow of molten steel in the ladle for treatment.

[0047] 4) Full protection casting: Full protection casting uses physical protection method for full protection casting, including: the ladle and the tundish are connected by an Al-C long shroud, and the long shroud is inserted into the molten steel in the tundish by 120mm.

[0048] 5) Cutting of ingot, inspection of ingot redness, and cleaning of burrs; 6) The hot ingot is sent to the soaking furnace for soaking; 7) After soaking, the ingot is descaled by high-pressure water; 8) Rolling: Use 1050 full continuous strip rolling mill to carry out controlled cold rolling on the ingot, and the thickness of the steel after rolling is greater than 6.0mm.

[0049] 10) Coiler: Coil the rolled steel using the steel coiler.

[0050] 11) Numbering, inspection, and storage: The steel products are sprayed with product numbers after coiling, and are stored for standby after passing the inspection.

[0051] The thickness of the Q355B steel smelted in Examples 1-3 is ≤6.0mm, which is Q355B thin steel; the thickness of the Q355B steel smelted in Examples 4-6 is >6.0mm, which is Q355B thick steel; the conventional Q355B steel smelting process does not distinguish between the thickness of 355B steel, Embodiment 6: The smelting process of Q355B steel is as follows: 1) Hot metal pretreatment: Hot metal pretreatment is to desulfurize the hot metal and remove the slag. The hot metal after treatment 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 hot metal after pretreatment is 8ppm, and the nitrogen concentration is 60ppm.

[0052] 2) Converter smelting: Converter smelting uses the combined blowing converter bottom blowing N2-Ar switching process for smelting.

[0053] 3) Slag washing + Ar blowing of top slag white slag treatment + Ti microalloying + silicon calcium wire feeding treatment includes the following steps: (1) Slag washing: When steel is tapped from the converter into the ladle, slag and lime slag are added 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 used as basic oxides, and CaF2, MgO, CaCl2 are used as fluxes; (2) Argon blowing treatment: After the molten steel is discharged into the ladle, argon gas is blown into the ladle from the bottom of the ladle. By controlling the pressure and time of argon blowing, the molten steel is boiled and refined; (3) Ti microalloying: Add 0.03% Ti to the ladle to microalloy the molten steel; (3) Silicon-calcium wire feeding treatment: use a wire feeding machine to feed the silicon-calcium wire into the center of the downward flow of molten steel in the ladle for treatment.

[0054] 4) Full protection casting: Full protection casting uses physical protection method for full protection casting, including: the ladle and the tundish are connected by an Al-C long shroud, and the long shroud is inserted into the molten steel in the tundish 110mm.

[0055] 5) Cutting of ingot, inspection of ingot redness, and cleaning of burrs; 6) The hot ingot is sent to the soaking furnace for soaking; 7) After soaking, the ingot is descaled by high-pressure water; 8) Rolling: Use 1050 full continuous strip rolling mill to carry out controlled cold rolling on the ingot, and the thickness of the steel after rolling is greater than 6.0mm.

[0056] 10) Coiler: Coil the rolled steel using the steel coiler.

[0057] 11) Numbering, inspection, and storage: The steel products are sprayed with product numbers after coiling, and are stored for standby after passing the inspection.

[0058] In Examples 1-3, the thickness of Q355B steel produced by the smelting process of Q355B steel is ≤6.0mm, and this steel is Q355B thin. In Examples 4-6, the thickness of Q355B steel produced by the smelting process of Q355B steel is >6.0mm, and this steel is Q355B thick. Q355B thin and Q355B thick are distinguished by smelting process and smelting by specifications, which can effectively save costs. The addition percentages of C, Si, Mn, S, P, Als, and Ti in the molten steel of Q355B thin and Q355B thick are shown in Table 1: Table 1 Examples 1-3 disclose the smelting process of Q355B thin gauge steel, and Examples 4-6 disclose the smelting process of Q355B thick gauge steel, which can effectively save costs by adopting different specifications for smelting; among them, in the smelting process of Q355B thin gauge steel, after taking measures to reduce Mn and cancel Ti microalloying, the Mn content is reduced by about 0.20% compared with the original process, and the Ti microalloying containing 0.028% in the original process is canceled. The amount of MnSi added per furnace of steel is reduced by about 440kg, and the amount of steel per ton is reduced by about 3.2kg / t. Calculated based on the MnSi alloy price of 6.513 yuan / kg in the steelmaking industry that month, the cost per ton of steel was reduced by about 20.84 yuan / t, the cancellation of the FeTi 0.98kg / t alloy addition reduced the Ti microalloying cost by 18.2 yuan / t, and the two items reduced the cost by about 39.04 yuan / t in total. After the Ti microalloying was cancelled in the Q355B thin steel smelting process, the fluidity of the molten steel was improved compared with the original process, and the pouring operation was smoother than the original process, reducing the non-steady-state operations of the water burning nozzle, stopping the flow and removing the sleeve for immersion, thereby improving the quality of the ingot and the product quality.

[0059] The Q355B steel smelting process described in Examples 1-3 was used to produce Q355B thin gauge steel, and the Q355B thin product was subjected to a performance test. 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 are shown in Table 2; Table 2 The Q355B steel smelting process described in Examples 1-3 is used to produce Q355B thin-gauge steel, and the performance of the Q355B thin-gauge steel is stable.

[0060] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention 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 invention.

Claims

1. A smelting process for Q355B steel, characterized in that: The process route includes: Hot metal pretreatment, converter smelting, slag washing, argon blowing, calcium feeding, full protection casting, billet cutting, billet red inspection, burr cleaning, hot delivery, soaking furnace soaking, high-pressure water descaling, rolling, coiling, coiling steel spraying, inspection, and storage; The molten iron pretreatment is to desulfurize the molten iron and remove the slag; the weight percentages of the remaining chemical components in the treated molten iron are: 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%.

2. A smelting process for Q355B steel according to claim 1, characterized in that: The pretreated molten iron contains 0.80-0.95% Mn.

3. A smelting process of Q355B steel according to claim 1, characterized in that: The oxygen concentration in the pretreated molten iron is less than 8 ppm, and the nitrogen concentration is less than or equal to 60 ppm.

4. The smelting process of a Q355B steel material according to claim 1, characterized in that: The converter smelting is carried out using a combined blowing converter bottom blowing N2-Ar switching process.

5. The smelting process of a Q355B steel material according to claim 1, characterized in that: The slag washing, argon blowing and calcium line feeding treatments include the following steps: (1) Slag washing: When the steel is tapped from the converter into the ladle, slag and lime slag are added into the ladle through the alloy chute for slag washing; (2) Argon blowing treatment: After the molten steel is discharged into the ladle, argon gas is blown into the ladle from the bottom of the ladle. By controlling the pressure and time of argon blowing, the molten steel is boiled and refined; (3) Silicon-calcium wire feeding treatment: use a wire feeding machine to feed the silicon-calcium wire into the center of the downward flow of molten steel in the ladle for treatment.

6. A smelting process for Q355B steel according to claim 5, characterized in that: The slag and white ash slag include: CaO, SiO2, Al2O3, CaF2, MgO, CaCl2; wherein CaO, SiO2, Al2O3 are used as basic oxides, and CaF2, MgO, CaCl2 are used as fluxes.

7. A smelting process for Q355B steel according to claim 1, characterized in that: The full protection casting uses a physical protection method to perform full protection casting, including: the ladle and the tundish are connected by an Al-C long shroud, and the long shroud is inserted into the molten steel in the tundish by 100-120mm.

8. The smelting process of a Q355B steel material according to claim 1, characterized in that: The rolling operation uses a 1050 fully continuous strip mill for controlled cold rolling.

9. A smelting process for Q355B steel according to claim 8, characterized in that: The thickness of the rolled steel is ≤6.0 mm.

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