S30432钢700℃持久σ相的析出及其对性能的影响

Precipitation Behavior ofσPhase in S30432 Steel During Creep Rupture Test at 700℃ and the Effect on Material Property

在Thermo-Calc软件模拟计算的基础上,采用透射电子显微镜和扫描电子显微镜对S30432钢700℃持久后的析出相特别是σ相进行分析,并研究其对持久塑性的影响.结果表明:S30432钢700℃持久后除存在富铜相、MX相和M23C6外,持久4 363h后在晶界析出块状的σ相;随着持久时间延长,σ相数量增加并粗化;晶界析出的块状σ相促使空洞形核和裂纹发展,对4 363~6 234h阶段持久塑性的骤降产生重要影响.

The precipitates in S30432 steel during creep rupture test at 700 ℃ were studied by means of Thermo-Calc software,transmission electron microscopy and scanning electron microscopy,with emphasis on the precipitation behavior ofσphase and the effect on the creep ductility.Results show that Cu-rich phase,MX phase and M23C6 carbide form in S30432 steel during creep rupture test at 700℃,and blockyσphase begins to precipitate at grain boundary after testing for 4 363 h.The blockyσphase increases both in number and size with the rise of creep rupture time.The rapid decrease of creep ductility after creep rupture test from 4 363 hto 6 234 his mostly ascribed to the blockyσphase at grain boundaries,since it plays an important role in the formation of cavities and in the development of intergranular cracks.