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采用真空感应炉冶炼了试验钢,并进行了不同工艺的热处理。采用光学显微镜、扫描电镜对组织进行了观察,对洛氏硬度进行了检测。结果表明,试验钢淬火组织主要为细小的板条马氏体+大量残余奥氏体+未溶析出相,经-80℃深冷处理、低温回火后残余奥氏体含量逐步减少;随着淬火温度提高,回火马氏体基体逐渐粗化,第二相粒子数量逐渐减少,尺寸也减小;1030℃淬火并深冷处理后在150℃回火,试验钢获得最高的硬度,随着回火温度提高,基体组织逐渐由回火马氏体转变为回火屈氏体再到回火索氏体,第二相粒子逐渐粗化;硬度值先几乎不变,当温度超过450℃硬度值迅速下降,650℃时降低至34HRC。
Vacuum induction furnace smelting the test steel, and conducted a different heat treatment process. The microstructure was observed by optical microscope and scanning electron microscope, and the Rockwell hardness was measured. The results show that the quenched microstructure of the test steel is mainly composed of fine lath martensite + a large amount of residual austenite + undissolved phase, and the residual austenite content gradually decreases after cryogenic tempering at -80 ℃. With the quenching The temperature increased, the tempered martensite matrix gradually roughened, the number of second phase particles gradually reduced, the size also decreases; 1030 ℃ quenched and cryogenic treatment at 150 ℃ after tempering, the highest hardness of the test steel, with the tempering The temperature of the matrix increases gradually from tempered martensite to tempered martensite to tempered sorbite, and the second phase particles gradually coarsen. The hardness values are almost unchanged first. When the temperature exceeds 450 ℃, the hardness value rapidly increases Decline, reduced to 34HRC at 650 ℃.