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利用金相显微镜、扫描电镜和X-射线衍射仪并通过冲击试验研究了P92钢经1050℃正火+不同温度回火后的微观组织和韧性变化。结果表明:正火后P92钢组织为典型的板条马氏体,并有一定量的残余奥氏体和M23C6析出相存在。回火温度较低时,P92钢的组织形态和冲击功变化不大,在500～600℃出现了马氏体板条碎化、大部分或全部残余奥氏体分解和一定的回火脆性;随回火温度升高组织中亚结构数量增多并出现块状铁素体,而冲击功则快速升高。
The microstructure and toughness of P92 steel after normalizing at 1050 ℃ and tempering at different temperatures were investigated by metallographic microscope, scanning electron microscopy and X-ray diffraction. The results show that P92 steel is a typical lath martensite after normalizing, and a certain amount of residual austenite and M23C6 precipitates exist. When the tempering temperature is low, the microstructure and impact energy of P92 steel do not change much. At 500 ~ 600 ℃, martensite lath, most or all of retained austenite and some temper brittleness appear. With the increase of tempering temperature, the number of sub-structures increased and massive ferrite appeared, while the impact energy increased rapidly.