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研究了回火温度对高碳钢断裂韧性及其他力学性能的影响。利用紧凑拉伸试样测量其平面应变断裂韧度,扫描电镜(SEM)观察回火后的组织演变规律及断裂韧度试样断口形貌。结果表明:随着回火温度的升高,马氏体逐渐分解消失,从过饱和α固溶体中析出的碳化物数量逐渐增多并发生聚集长大,强度和硬度下降,塑性、断裂韧性和冲击韧性上升。位错强化和固溶强化作用减弱是试验钢强度降低、韧性升高的主要原因。
The effect of tempering temperature on fracture toughness and other mechanical properties of high carbon steel was studied. Tensile toughness of plane strain was measured by compact tensile specimens. Microstructure evolution and fracture surface morphology of specimens after tempering were observed by scanning electron microscopy (SEM). The results show that as the tempering temperature increases, the martensite gradually decomposes and disappears. The amount of carbides precipitated from the supersaturated α solid solution gradually increases and aggregates and grows, the strength and hardness decrease, and the plasticity, fracture toughness and impact toughness rise. The dislocation strengthening and the weakening effect of solid solution strengthening are the main reasons for the decrease of strength and toughness of the test steel.