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CN-121992295-A - 1.5-3.1 Mm high-plasticity and toughness pickled steel for automobiles and manufacturing method thereof

CN121992295ACN 121992295 ACN121992295 ACN 121992295ACN-121992295-A

Abstract

The invention relates to 1.5-3.1 mm high-plasticity and toughness steel for an acid-washing automobile and a manufacturing method thereof, wherein the steel plate comprises the following chemical components in percentage by weight ：C 0.045~0.065 wt.%,Si≤0.30 wt.%,Mn 1.15~1.75 wt.%,Als 0.15~0.55 wt.%,Nb 0.015~0.050 wt.%,Ti 0.010~0.065 wt.%,Ca 0.0005~0.0031 wt.%,P≤0.023 wt.%,S≤0.0050 wt.%,N≤0.0050 wt.%, and the balance of Fe and unavoidable impurities. The steel for the pickled automobile is manufactured by the process flow of molten iron pretreatment, converter smelting, alloy fine adjustment, LF refining, continuous casting, hot rolling (finishing), pickling (leveling), oiling, fine packaging, pickling coil, continuous casting blank cleaning-free corner and hot-pack rolling without widening, wherein the surface quality grade of the pickling coil is FC, the 90-degree direction yield strength is 510-460 MPa, the tensile strength is 580-6615 MPa, the elongation A 50 is more than or equal to 21.5%, the Hole Expansion Ratio (HER) is more than or equal to 80%, and the material has excellent stamping forming performance at a market client, high customer satisfaction and strong market competitiveness.

Inventors

  • CHEN ZHONG
  • GU HAIRONG
  • Peng Zhengbo
  • CUI LEI
  • HUANG CHUANGEN
  • MA CONG
  • LIU YANG
  • TIAN ZHIJUN
  • LU QIANQIAN

Assignees

  • 马鞍山钢铁有限公司

Dates

Publication Date
20260508
Application Date
20260121

Claims (9)

  1. 1. A1.5-3.1 mm high-ductility and toughness pickled steel for automobiles is characterized in that the steel plate comprises the following chemical components by weight percent ：C 0.045~0.065 wt.%,Si≤0.30 wt.%,Mn 1.15~1.75 wt.%,Als 0.15~0.55 wt.%,Nb 0.015~0.050 wt.%,Ti 0.010~0.065 wt.%,Ca 0.0005~0.0031 wt.%,P≤0.023 wt.%,S≤0.0050 wt.%,N≤0.0050 wt.%,, the balance Fe and unavoidable impurities, the steel plate has a metallographic structure of 71-83.5% by volume percent of ferrite and 16.5-29% by volume percent of granular bainite, and the grain size of the ferrite is 11-13.5.
  2. 2. The 1.5-3.1 mm high-ductility and toughness pickled steel for automobiles according to claim 1, wherein the steel plate comprises the following chemical components in percentage by weight ：C 0.045~0.060 wt.%,Si≤0.25 wt.%,Mn 1.35~1.65 wt.%,Als 0.19~0.50 wt.%,Nb 0.023~0.045 wt.%,Ti 0.015~0.055 wt.%,Ca 0.0010~0.0025 wt.%,P≤0.015 wt.%,S≤0.0039 wt.%,N≤0.0045 wt.%, and the balance of Fe and unavoidable impurities.
  3. 3. The 1.5-3.1 mm high-ductility, pickled automotive steel according to claim 1, wherein the pickled automotive steel has a width of 900-1680 mm.
  4. 4. The 1.5-3.1 mm high-ductility and toughness pickled steel for automobiles according to claim 1, wherein the 90-degree directional yield strength is 510-560 MPa, the tensile strength is 580-6615 MPa, the elongation is more than or equal to 21.5%, and the hole expansion rate is more than or equal to 80%.
  5. 5. The 1.5-3.1 mm high-ductility and toughness pickled steel for automobiles according to claim 1, wherein the manufacturing process flow comprises molten iron pretreatment, converter smelting, alloy fine adjustment, LF refining, continuous casting, hot rolling, finishing, pickling, leveling, oiling and packaging and pickling coil.
  6. 6. A method for producing 1.5 to 3.1mm high ductility and toughness steel for acid-washed automotive vehicles according to any one of claims 1 to 5, comprising the steps of: S1, performing calcium treatment after the refining process of an LF furnace is finished, blowing argon by a stopper rod to promote the inclusion to float upwards, controlling the temperature of a tundish to be 10-30 ℃ above the target liquidus temperature, throwing a dynamic soft reduction and an electromagnetic roller, wherein the soft reduction is 4.5-6.5 mm, the rated current of the electromagnetic roller is 135-160A, and the rated frequency is 2.3-3.9 HZ; S2, hot rolling, namely discharging the continuous casting billet at any position in the rolling direction at 1215-1265 ℃, wherein the continuous casting billet is in a furnace for 160-250 min, the final rolling temperature is 830-890 ℃, and the length of a laminar cooling section is not less than 65m; S3, an acid pickling process, namely, the temperature of acid liquor is 65-86 ℃, the flattening elongation is 0.3-0.9%, the running speed of an acid pickling line is not more than 190m/min, the strip steel is dried at the temperature of 100-150 ℃, then electrostatic oiling is carried out, the oil coating amount is 1.0-3.1 g/m 2 , and an acid pickling coil is obtained after packaging.
  7. 7. The method for manufacturing 1.5-3.1 mm high-ductility and toughness pickled steel for automobiles according to claim 6, wherein in step S1, the continuous casting billet pulling speed is controlled within the range of 1.0-1.5 m/min, and the thickness of the continuous casting billet is 190-250 mm.
  8. 8. The method for manufacturing the steel for the acid-washed car with high ductility and toughness according to claim 6, wherein in the step S2, a discontinuous cooling mode is adopted in a laminar cooling section of a hot rolling process, strip steel is firstly cooled to 650-695 ℃ for 3-9 seconds by water, then the strip steel is cooled to 410-500 ℃ by air for coiling to obtain a hot rolled coil, if the hot rolled coil is bad in shape, finishing is needed to correct the shape, the finishing elongation is 0.5-2.3%, and if the hot rolled coil is good in shape, finishing is not performed, and an acid washing line is directly arranged.
  9. 9. The method for producing 1.5-3.1 mm high-ductility and toughness pickled steel for automobiles according to claim 6, wherein in step S3, the acid concentration in the pickling step 1# tank is 31-68 g/L, the acid concentration in the 2# tank is 95-150 g/L, and the acid concentration in the 3# tank is 135-190 g/L.

Description

1.5-3.1 Mm high-plasticity and toughness pickled steel for automobiles and manufacturing method thereof Technical Field The invention relates to the technical field of steel manufacturing for acid-washed automobiles, in particular to 1.5-3.1 mm steel for acid-washed automobiles and a manufacturing method thereof. Technical Field Compared with hot dip galvanized automobile steel and continuous annealed automobile steel with the same thickness, the steel for the pickled automobile has relatively low n value and r value, so that the steel for the pickled automobile has no obvious competitive advantage in forming performance. Meanwhile, compared with hot dip galvanized steel for automobiles, the pickled steel for automobiles has poor corrosion resistance. Therefore, the steel for the pickled automobile has the advantage that the forming performance of the steel for the pickled automobile is improved as much as possible under the premise of keeping the price advantage, so that the steel for the pickled automobile has no problem of forming failure when being used at a market client, improves the satisfaction degree of the market client and wins a long-term stable market order source. The prior art at home and abroad shows that in order to ensure that the steel for the acid-washed automobile with the tensile strength of 600MPa has excellent forming performance at a market client, a high Si alloy design is generally adopted, but Si element is one of key factors influencing the surface quality of an acid-washed coil, and particularly when the key process control such as the tapping temperature of a continuous casting blank in a hot rolling procedure, the furnace time, rough rolling descaling and the like does not meet the technical standard, the high surface quality of the acid-washed coil and the stability thereof cannot be ensured. The Chinese patent CN114540707B discloses 590MPa grade cold-rolled high-strength steel and a production method thereof, wherein the steel plate comprises the chemical components of ：C 0.07~0.14 wt.%,Si 0.40~0.70 wt.%,Mn 1.50~2.00 wt.%,Al 0.25~0.50 wt.%,P≤0.012 wt.%,S≤0.008 wt.%,N≤0.004 wt.%,, 0.005-0.015 wt.% of Ti, 0.005-0.015 wt.% of Nb, si and Al, more than or equal to 0.60 of Si+Al, more than or equal to 1.0 and less than or equal to 1.6 of Si/Al, and the balance of Fe and unavoidable impurities. The manufacturing process flow of the related steel plate comprises smelting, casting, slab heating, hot rolling, cooling, coiling, pickling, cold rolling and continuous annealing. The metallographic structure of the steel plate contains 65-80% by volume of ferrite, 10-20% by volume of bainite, 1-15% by volume of martensite and 3-8% by volume of residual austenite, and the grain size of ferrite is less than or equal to 5um. The yield strength of the steel plate is more than or equal to 340MPa, the tensile strength is more than or equal to 590MPa, the elongation A 80 is more than or equal to 30%, the uniform elongation is more than or equal to 16%, and the Hole Expansion Ratio (HER) is more than or equal to 40%. The hot rolling process plate blank heating time is 30-100 min, and the rolling difficulty is increased due to the short heating time. (2) The average value of the content of the C element is higher, the equivalent carbon equivalent is more than 0.080, and the continuous casting blank can not be rolled without clearing the angle and widening hot-charging. (3) The average value of the Si element content is higher, and obvious red rust defects exist on the surface of the hot rolled coil. Chinese patent No. CN113186461B discloses a high-strength plastic deep-rolling cold-rolled steel plate and a preparation method thereof, wherein the steel plate comprises the chemical components of ：C 0.23~0.25 wt.%,Si 0.60~1.50 wt.%,Mn 2.80~3.50%,Al 0.50~0.90 wt.%,V 0.13~0.15 wt.%,Cr 0.30~0.50 wt.%,Ni 0.10~0.50 wt.%,Mo 0.10~0.50 wt.%,Cu 0.10~0.50 wt.%,Nb 0.020~0.030 wt.%,B 0.002~0.005 wt.%,Ti≤0.005 wt.%,Ca≤0.005 wt.%,P≤0.050 wt.%,S≤0.050 wt.%, weight percent, less than or equal to 2.00 and wt weight percent of Si+Al, and the balance of Fe and unavoidable impurities. The manufacturing process flow of the related steel plate comprises smelting, continuous casting, hot rolling, cryogenic rolling and continuous annealing. The metallographic structure of the steel plate contains a certain amount of reverse austenite, the yield strength is 650-800 MPa, the tensile strength is more than or equal to 1000MPa, the elongation is more than or equal to 30%, and the strength-plastic product is more than or equal to 30GPa%. The patent product and the process have the characteristics that (1) the alloy content of the patent product is obviously higher, and the welding difficulty is extremely high. (2) The alloy cost is obviously higher, and the market competitiveness of the alloy is directly affected. (3) Under the precondition that the content of Si element is obviously higher, no method is described for eliminating