回火温度对高碳钢断裂韧性的影响

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。

Effect of tempering temperature on fracture toughness of high carbon steel

The effect of tempering temperatures on fracture toughness and other mechanical properties of high car-bon steel was investigated.Plane strain fracture toughness was tested with compact tension specimen.Microstruc-ture and fracture morphology of KIC samples after tempering treatment were examined by scanning electron micro-scope (SEM).The results show that the as-quenched martensite phase gradually disappears,carbides coarsen and the amount of precipitated carbide increases with the tempering temperature.The strength and hardness of the steel decreases with the increase of tempering temperature while the ductility and toughness improves.The main reasons for the change of strength and toughness have close relationship with the weakening of solid solution strengthening and dislocation strengthening.