【摘要】 针对Q345B低碳贝氏体钢，开展了淬火+亚温淬火及回火处理试验，借助金相、扫描电子显微镜、冲击及拉伸试验等检测，研究不同热处理工艺对其金相组织及力学性能变化的影响规律。结果表明：随亚温淬火温度的降低，试验钢抗拉强度、屈服强度、屈强比逐渐降低，断面延伸率增加；当回火温度从350℃升高到620℃时，试验钢抗拉强度和屈服强度逐渐减小、冲击功增大、断面延伸率增大，而屈强比达到峰值后减小。试验钢亚温淬火金相组织为板条状贝氏体+粒状贝氏体+少量铁素体，随亚温淬火温度降低，贝氏体含量逐渐减少、铁素体含量逐渐增多；随回火温度降低，铁素体含量逐渐减少，贝氏体板条逐渐细化。更多还原

【Abstract】 Experiments involving quenching+intercritical quenching and tempering treatments were conducted on Q345B low-carbon bainitic steel. The influence of different heat treatment processes on microstructural evolution and mechanical properties was investigated using metallographic examination,scanning electron microscopy(SEM),impact testing,and tensile testing. The results demonstrate that with intercritical quenching temperature decreasing,tensile strength,yield strength,and yield ratio gradually decrease,elongation increases. With tempering temperature increasing from 350 ℃ to 620 ℃,tensile strength and yield strength gradually decrease,impact energy and percentage reduction of area increase,the yield ratio reaches a peak value before decreasing. The microstructure after intercritical quenching consists of lath bainite+granular bainite+a small amount of ferrite. As the intercritical quenching temperature decreases,the bainite content gradually decreases,the ferrite content gradually increases. As the tempering temperature decreases,the ferrite content gradually decreases,and the bainite laths become progressively refined.更多还原