调质工艺对G115钢组织性能的影响

Effect of quenching and tempering process on properties and microstructure of G115 steel

新型马氏体耐热钢G115是我国630~650℃超超临界燃煤发电机组重要的候选材料。研究了不同调质工艺对G115棒材组织性能的影响。结果表明,采用两次调质工艺,室温拉伸和650℃高温拉伸强度均提高,冲击功提升尤为显著。随着两次调质工艺中第一次淬火温度的升高,强度和冲击功均有提升趋势。采用金相显微镜、扫面电镜观察分析了不同调质工艺的组织差异,两次调质工艺的晶粒明显细于一次调质,且回火板条组织保留更明显,碳化物形貌更细小、分布更弥散。随着两次调质工艺中第一次淬火温度的升高,晶粒变粗但均匀性更好。

The novel martensitic heat resistant steel G115 was designed for thick section boiler components of USC power plants at 630-650℃.The effect of quenching and tempering process on properties and microstructure of G115 steel was investigate.The samples with two quenching and tempering processes have higher tensile strength at room temperature and at 650℃,and the impact energy is improved particularly remarkable.With the increase of the first quenching temperature,the strength and the impact energy have an increasing trend.The microstructure differences of different quenching and tempering processes were observed by metallographic microscope and scanning electron microscope.The grain size of the two quenching and tempering processes is obviously finer than that of one quenching and tempering,and the tempered martensite lath is more obvious,and the carbides and other precipitates are finer and distribute more homogeneously.As the first quenching temperature increases,the grains become coarser but more uniform.