Effect of Long-Term Ageing at 600 ℃ on Microstructure of ZGlCrlOMoWVNbN Martensitic Heat-Resistant Steel

摘要

A new kind of martensitic ZG1Cr10MoWVNbN heat-resistant steel has been attracted more attentions in recent years, which is mainly applied in ultra-supercritical steam turbines. The ageing property for ZG1Cr10MoWVNbN heat-resistant steel is very important because it often serves for long-time at high-temperature environment. Herein, a long-term ageing heat treatment was conducted on ZG1Cr10MoWVNbN steel at 600 °C heat for 17,000 hours. The microstructure evolution and property variation of the ZG1Cr10MoWVNbN steel were analysed before and after ageing, and also the effect of the precipitates on the mechanical properties was studied. The result showed that strength, the plastic index and impact power of the ZG1Cr10MoWVNbN steel were gradually decreased after long-term and high-temperature ageing at 600 °C due to the changes of martensite morphology and the coarsening of M23C6 carbide precipitation phase. Furthermore, fine precipitation of matrix MX carbide can also attribute to the change of mechanical properties at high temperature.