长时服役后T92钢管的微观组织及力学性能变化

通过扫描电镜、透射电镜等技术定量研究了T92耐热钢服役80 000 h后的微观组织结构和力学性能,并与未服役的同批次材料进行了对比。结果表明,在服役80 000 h后,T92钢管材的马氏体板条上析出了大量的M₂₃C₆相和Laves相,在板条内部析出MX相,马氏体板条宽度明显增加,但仍然保持着典型的马氏体板条形貌。T92钢室温和610 ℃高温抗拉强度、屈服强度均较未服役样品的低,但室温条件下性能相差较小,而高温条件下的下降幅度较大,且屈服强度接近标准要求的下限。析出相强化和板条强化是T92耐热钢在长时服役后仍具有较高性能的原因。

Microstructure evolution and property change of T92 heat resistant steel pipe after long term service

Microstructure evolution and mechanical properties of the T92 heat resistant steel pipe after 80 000 h service were studied by means of scanning electron microscopy and transmission electron microscopy and compared with the same batch of standby materials. The results show that after 80 000 h service, a large amount of M₂₃C₆ phase and Laves phase are precipitated on the martensite lath of the T92 steel, and MX phase is precipitated inside the lath. The width of the martensite slats has also increased significantly after service, but the typical martensitic slats are still maintained. The tensile strength and yield strength at room temperature and high temperature (610 ℃) of the T92 steel are reduced compared to the standby steel, and the difference of which at room temperature is small, while it decrease largely at high temperature. Precipitated phase strengthening and lath strengthening are the fundamental reasons for high performance of the T92 heat resistant steel after long-term service.