600 MPa低硅Nb-Ti微合金化优质3.5 mm热轧双相钢板的开发

通过真空感应炉熔炼和浇铸的50 kg锭锻成40 mm×150 mm坯和热轧成10 mm板以及热模拟试验研究了开发的低硅Nb-Ti微合金化双相钢(/%:0.082C，0.15Si，1.20Mn，0.010P，0.002S，0.020Nb，0.015Ti，0.045Al，0.0035N)静态和动态连续冷却转变(CCT)曲线、组织(11%马氏体+89%铁素体)和力学性能(抗拉强度682 MPa)。并通过铁水脱硫-260 t BOF-LF-RH-230 mm×1300 mm连铸-热轧工艺试制了低硅双相钢(/%:0.075C，0.15Si，1.16Mn，0.012P，0.003S，0.016Nb，0.015Ti，0.033Al，0.0043N)3.5mm板。结果表明，精轧出口温度810℃，水冷至700℃，空冷4.5 s，卷取温度150℃时，该钢的组织为15%马氏体+85%铁素体,晶粒度12~12.5级，抗拉强度672~692 MPa，伸长率24.0%~28.5%，屈强比0.65~0.67，钢板冲压成塑性能优良，制造的轿车轮辐弯曲疲劳性能15×10⁴次。

Development of 600 MPa Low Silicon and Nb-Ti Microalloying High Quality 3.5 mm Hot-Rolled Dual Phase Steel Plate

The static and dynamic continuous cooling transformation (CCT) curves, structure (11% martensite + 89% feiTite) and mechanical properties (tensile strength 682 MPa) of developed low silicon and Nb-Ti Microalloying dual phase steel (/% : 0.082C, 0.15Si, 1.20Mn, 0.010P, 0.002S, 0.020Nb, 0.015Ti, 0.045Al, 0.0035N) have been tested and studied by melting in a vacuum induction furnace, casting 50 kg ingot, forging to 40 mm x 150 mm slab and hot rolling to 10 mm plate and thermal simulation testing. And 3.5 mm low silicon dual phase steel plate (/% : 0.075C, 0.15Si, 1.16Mn, 0.012P, 0.003S, 0.016Nb, 0.015Ti, 0.033Al, 0.0043N) has been pilot-produced by hot metal desulphurization-260 t BOF-LF-RH-230 mm x 1300 mm slab concasting-hot rolling process. Results show that with finished rolling 810 °C , water cooling to 700 ℃, air cooling for 4.5 s and coiling at 150 °C , the structure of steel is 15% +85% ferrite with gain size rating 12-12.5, the tensile strength of steel is 672-692 MPa with yield-ultimate strength ratio 0. 65 ~0. 67, and the yield of steel is 24.0%-28.5% . The steel plate has nice stamping performance and the bending fatigue life of manufactured wheel rib of car is 15 x 10⁴.