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采用光学显微镜(OM)、扫描电子显微镜(SEM)、洛氏硬度计、冲击试验机等观察和分析了7Cr17Mo马氏体不锈钢在980～1110℃不同温度淬火下的组织特征和性能变化。结果表明,淬火组织为残留奥氏体和碳化物分布于隐针马氏体基体上,碳化物以(Fe,Cr)23C6为主。随着淬火温度的升高,残留奥氏体含量增加,马氏体过饱和度增加,针状马氏体组织变粗,1060℃时硬度升高到最大值59 HRC。冲击试验结果表明在980～1080℃淬火时,随淬火温度升高,冲击韧性提高,1080℃时冲击韧性最好,其后下降。SEM断口形貌表明室温下冲击断裂方式为微孔聚集型断裂。
The microstructures and properties of 7Cr17Mo martensitic stainless steel after quenching at 980-1110 ℃ were observed and analyzed by optical microscope (OM), scanning electron microscope (SEM), Rockwell hardness tester and impact tester. The results show that the retained austenite and carbides are distributed on the hidden matrix of martensite, and the carbides are (Fe, Cr) 23C6. With the increase of quenching temperature, the content of retained austenite increases, the degree of supersaturation of martensite increases, and the microstructure of acicular martensite becomes coarse. The hardness increases to 59 HRC at 1060 ℃. Impact test results show that when quenching at 980 ~ 1080 ℃, with the increase of quenching temperature, the impact toughness increases, the impact toughness is the best at 1080 ℃, and then decreases. SEM fracture morphology shows that the impact fracture mode at room temperature is micropore aggregation type fracture.