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利用光学显微镜、扫描电镜、透射电镜观察研究了淬火温度(770~1160℃)对3Cr2Mo钢组织的影响,并测定了相应的硬度及常温冲击韧度。结果表明,出厂态试验钢的硬度和冲击韧度较低,淬火后硬度和冲击韧度均得到大幅提高。在850~1000℃较宽温度范围内淬火,试验钢均具有较好的硬化和韧化性能,再经560℃/2h回火处理后,淬火温度对回火硬度影响很小,对应的硬度值波动不超过0.2HRC。淬火温度低于880℃时,碳化物无法充分溶入基体,硬度和韧性较低;淬火温度过高,马氏体粗化,硬度和韧性相应降低。经880℃淬火+560℃/2h回火后,3Cr2Mo钢的组织为回火索氏体+细小弥撒分布的碳化物,此时具有较好的强韧性。
The effect of quenching temperature (770 ~ 1160 ℃) on the microstructure of 3Cr2Mo steel was studied by optical microscope, scanning electron microscope and transmission electron microscope. The corresponding hardness and impact toughness at room temperature were measured. The results show that the hardness and impact toughness of the as-cast test steel are lower, and the hardness and impact toughness of the test steel after quenching are greatly increased. In the 850 ~ 1000 ℃ wide temperature range of quenching, the test steel has good hardening and toughening properties, and then 560 ℃ / 2h tempering, the quenching temperature on the tempering hardness is small, the corresponding hardness value Fluctuation does not exceed 0.2HRC. When the quenching temperature is lower than 880 ℃, the carbides can not fully dissolve into the matrix, and the hardness and toughness are low. If the quenching temperature is too high, the martensite coarsens and the hardness and toughness decrease correspondingly. After 880 ℃ quenching + 560 ℃ / 2h tempering, 3Cr2Mo steel microstructure tempered sorbite + small mass distribution of carbide, this time has good strength and toughness.