Abstract: The production flowsheet of 20mm plate of tested steel EH420 (/% : 0.20C, 0.38Si, 1.63Mn, 0.007P, 0.001S, 0.062V, 0.017Nb, 0.009Ti, 0.021 Alt, 0.38Ni, 0.015Cu) is 210t BOF-LF-RH-230 mm slab casing-rolling. The tensile test of steel EH420 is carried out at ambient temperature, 450 °C , 480 °C , 500 °C and 600 °C, the morphology of fracture of steel tensile specimen is observed by scanning electron microscope and the fracture mechanism of steel is analyzed. Results show that the yield strength of steel at ambient temperature is 443 MPa and the yield strength of the steel at 480°C is 270 MPa which is basically equal to two-thirds of the yield strength of steel at ambient temperature, therefore the steel EH420 has fire resistance at less than 480 °C.

Key words: Steel EH420 for Offshore Drilling Platform, Fire Resistance, Structure, Tensile Fracture

摘要： 试验用EH420钢(/%:0.20C，0.38Si，1.63Mn，0.007P，0.001S，0.062V，0.017Nb，0.009Ti，0.021Alt，0.38Ni，0.015Cu)20mm板的生产流程为210t BOF-LF-RH-230mm坯连铸-热轧。分别在室温、450、480、500、600℃对EH420钢进行了拉伸试验，并通过扫描电镜观察了拉伸试样断裂形貌和分析了断裂机理。结果表明,该钢室温屈服强度为443 MPa，480℃屈服强度270 MPa，基本为室温屈服强度2/3，因此EH420钢在480℃以下具有耐火性。

关键词: 海洋平台用钢EH420, 耐火性, 组织, 拉伸断口