低焊接裂纹敏感性钢板组织和性能研究

Research on Microstructure and Properties of Steel Plate with Low Welding Crack Sensibility

采用低碳、低碳当量(Ceq)、低焊接裂纹敏感性指数(Pcm)的合金体系路线,利用100 kg真空感应炉进行试验钢冶炼,在TMCP及调质的工艺下在实验室研制800 MPa级水电工程用低焊接裂纹敏感性钢。对试验钢的强度、冲击及弯曲等力学性能进行了检测,并利用光学显微镜(OM)和场发射扫描电镜(SEM)对试验钢的显微组织及断口形貌进行分析。结果表明,试验钢室温显微组织为回火索氏体,各项力学性能优良,试验钢屈服强度、抗拉强度、断后伸长率分别为788 MPa、842 MPa、18.1%,-40℃低温冲击吸收功为197 J,强韧性匹配好,焊接裂纹敏感指数低,满足使用性能要求。

The 800 MPa grade hydropower engineering steel with low welding crack sensibility is developed through smelting test steel with 100 kg vacuum induction furnace as well as thermal mechanical control processing(TMCP),quenching and tempering processes adopting the alloy system route of low carbon,carbon equivalent(Ceq)and welding crack sensibility index(Pcm)in laboratory.Such mechanical properties as the strength,impact and bending of test steel are tested as well as its microstructure and fracture morphology are analyzed with the optical microscope(OM)and field emission scanning electron microscope(SEM).The results showed that its microstructure at room temperature was tempered sorbite,all its mechanical properties were excellent,its yield strength,tensile strength and elongation after fracture were 788 MPa,842 MPa and 18.1%,low temperature impact absorbing energy at-40℃was 197 J,strength and toughness well matched as well as welding crack sensitivity index was low,which could meet the performance requirements in use.