【摘要】 研究了淬火温度（860, 880和900℃）对42CrMo钢原奥氏体晶粒内的晶体学packet、block单元及析出相种类、尺寸的影响，并分析了组织特征对力学性能的影响。采用基于电子背散射衍射（EBSD）表征实现的组织可视化和定量化技术，分析了基体晶体学特征。结果表明：奥氏体化温度适当升高导致原奥氏体晶粒尺寸增大，导致马氏体转变形成更高密度的block界面，但packet界面密度则相应降低；高密度Σ3-block界面（V1/V2变体对）的大量形成，有利于42CrMo钢塑韧性的提高，但原奥氏体晶粒粗化也引起屈服强度的下降；在较低奥氏体化温度（860℃）淬火后进行回火处理时，获得针状θ-Fe₃C型碳化物及富Cr球状碳化物，形成于Fe-Cr有序相中，保持[001]_α//[011]_θ的位向关系，可能与奥氏体化温度较低导致Cr元素分布不均有关；随着奥氏体化温度升高至900℃,形成更多的粗化的球状θ-Fe₃C型碳化物，加之具有较高密度的block界面，其强度与塑性匹配效果更优，屈强比较低。更多还原

【Abstract】 Effects of quenching temperatures（860 ℃, 880 ℃, and 900 ℃） on the crystallographic packet, block unit, and precipitation phase types and sizes within the austenite grains of 42CrMo steel were studied, and the influence of microstructure characteristics on mechanical properties was analyzed. The microstructure visualization and quantification techniques based on electron backscatter diffraction（EBSD） characterization were used to analyze the crystallographic characteristics of the matrix. The results show that an appropriate increase in austenitizing temperature leads to an increase in the grain size of the prior austenite, resulting in the formation of higher density of block boundaries through martensitic transformation, while the density of packet boundaries decreases accordingly. The extensive formation of high-density Σ3 block boundaries（V1/V2 variant pairs） is beneficial for improving the plasticity and impact toughness of the 42CrMo steel, but the coarsening of prior austenite grains also leads to a decrease in yield strength. After quenching at a lower austenitizing temperature（860 ℃） and tempering treatment, acicular θ-Fe₃C carbides and Cr-rich spherical carbides formed in the Fe-Cr ordered phases are obtained, maintaining the orientation relationship of [001]_α//[011]_θ between martensitic matrix and θ-Fe₃C carbides, which may be related to the uneven distribution of Cr elements caused by the lower austenitizing temperature. As the austenitizing temperature increases to 900 ℃, more coarsened spherical θ-Fe₃C carbides are formed, coupled with a higher density of block boundaries, resulting in a better match between strength and plasticity, and a lower yield strength-to-tensile strength ratio.更多还原