Microstructural Evolution of P92 Steel During Long-Term Aging

The mechanical properties and microstructure evolution of P92 steel were investigated after aging up to 11,000 h at 923 K. Charpy impact and tensile tests were carried out to study the strength and ductility of aged P92 steel. In addition, microstructure evolution of the samples during long-term aging was investigated with X-ray diffraction, optical microscopy and scanning electron microscope (SEM). Then, statistical quantitative image analysis based on SEM images was used to evaluate the precipitation during long-term aging. The mechanical properties were found to be associated with the evolution of precipitation, especially the coarsening of Laves-phase. Results show that the ductility and strength of P92 steel decrease with the growth of Laves-phase during short-term aging (shorter than 1000 h). However, as the aging time further increasing, the ductility and strength of P92 steel decrease slowly with the coarsening of Laves-phase.