热处理对9Cr低活化马氏体钢组织和力学性能的影响

Effect of Heat Treatment on Microstructure and Mechanical Properties of 9Cr Low Activation Martensitic Steel

研究了热处理对9Cr低活化马氏体钢显微组织和力学性能的影响。用光学显微镜和扫描电子显微镜观察了材料的显微组织、拉伸断口和冲击断口;用X射线衍射仪检测了材料的晶体结构。结果表明:9Cr低活化马氏体钢的晶粒尺寸从950℃的6.28μm增加到1200℃的66.5μm。两种热处理工艺(950℃×30min水冷+780℃×90min空冷和1050℃×30min水冷+780℃×90min空冷)处理后的9Cr低活化马氏体钢显微组织为全马氏体。二种工艺处理后拉伸力学性能相近,但冲击性能差别明显。二者的韧脆转变温度分别为-72℃和-62℃。选择950℃×30min水冷+780℃×90min空冷的热处理工艺能够提高9Cr低活化马氏体钢的冲击韧度。

The effects of heat treatment on the microstructure and mechanical properties of 9Cr low activation martensitic（LAM） steel were studied.The microstructure and fracture surfaces were observed by optical microscopy,scanning electron microscopy and X-ray diffraction analysis.The results show that the grain size of 9Cr LAM steel increases from 6.28 μm at 950 ℃ to 66.5 μm at 1200 ℃.The microstructure of 9Cr LAM steel is full martensite after heat treatment（950 ℃ × 30 min,water quenching and 780 ℃ × 90 min,air cooling（named 9Cr-1） and 1050 ℃ × 30 min,water quenching and 780 ℃ × 90 min,air cooling（named 9Cr-2））.The identical tensile properties of 9Cr-1 and 9Cr-2 are obtained,while the impact properties are significantly different.The ductile brittle transition temperature of 9Cr-1 and 9Cr-2 is-72 ℃ and-62 ℃,respectively.The absorbed energy of 9Cr-1 is much higher than that of 9Cr-2.The heat treatment of 950 ℃ × 30 min,water quenching and 780 ℃ × 90 min,air cooling is a favorite condition for 9Cr LAM steel to obtain superior impact toughness.