Structural microdamageability of steels of the steam pipelines of thermal power plants

Abstract

We show that, under conditions of long-term operation of 12Kh1MF and 15Kh1M1F steels at 545–560°C, structural-phase changes occur in them under the action of temperature-force factors, namely, the amount of perlite decreases, carbides are spheroidized, the boundaries of ferrite grains migrate, and their size grows. Such changes under creep conditions favor the formation of pores along grain boundaries. The intensity of pore formation is maximum on the external stretched surface of bend, which leads here to the initiation of intergranular cracks and decreases the lifetime of steam pipelines.