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借助强度和硬度测量手段以及显微组织观察及EDS能谱分析,研究了奥氏体化温度和时间、回火温度对一种实验室冶炼的马氏体不锈钢的微观组织和力学性能的影响。实验结果表明:奥氏体化温度可以显著影响材料的力学性能,当奥氏体化工艺为1050℃-60 min时,材料的硬度最大(49 HRC),抗拉强度最高(1800 MPa)。在回火温度为400~500℃的范围内,回火温度的升高导致了M_7C_3相的沉淀和二次硬化,使材料的硬度和抗拉强度轻微升高;当回火温度进一步升高至700℃时,M_7C_3碳化物发生粗化并部分地转变为M_(23)C_6碳化物,材料的硬度和抗拉强度明显降低。试样在200℃和700℃回火后的拉伸断口表现出混合断裂机理(脆性和韧性),而在500℃表现为韧性特征。该材料最佳的热处理工艺为1050℃-60 min奥氏体化处理+500℃-60min回火处理。
The effects of austenitizing temperature and time, tempering temperature on the microstructure and mechanical properties of a laboratory smelted martensitic stainless steel were investigated by means of strength and hardness measurement, microstructure observation and EDS EDS. The experimental results show that the austenitizing temperature can significantly affect the mechanical properties of the material. When the austenitizing process is 1050 ℃ -60 min, the hardness of the material is the highest (49 HRC) and the tensile strength is the highest (1800 MPa). When the tempering temperature is in the range of 400-500 ℃, the increase of the tempering temperature leads to the precipitation and secondary hardening of the M_7C_3 phase, which leads to a slight increase in the hardness and tensile strength of the material. When the tempering temperature further increases to At 700 ℃, the carbides of M_7C_3 coarsened and partially transformed into M_ (23) C_6 carbides, the hardness and tensile strength of the materials decreased obviously. Tensile fracture after tempering at 200 ℃ and 700 ℃ showed mixed fracture mechanism (brittleness and toughness), but showed toughness at 500 ℃. The material is the best heat treatment process for austenitizing 1050 ℃ -60 min + 500 ℃ -60min tempering.