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本文考察了锻后正火对35MnVN钢显微组织和机械性能的影响;通过系列示波冲击试验和定量金相方法,分析探讨了影响冲击韧性的微观因素以及冲击断裂机制。结果表明:加热温度不超过1000℃的正火处理可以细化纲的组织,增加先析铁素体含量,从而在保证较高强度水平的同时,提高冲击韧性,降低韧脆转变温度,先共析铁素体含量为冲击韧性的主要影响因素。随着原始奥氏体晶粒的粗化和先析铁素体含量的减少,断裂机制由应变诱导准解理断裂变为应力诱导解理断裂;冲击功由受裂纹扩展功控制变为受裂纹形成功控制。
In this paper, the effects of normalized forging on the microstructure and mechanical properties of 35MnVN steel were investigated. Through the series of oscillometric impact tests and quantitative metallographic methods, the microscopic factors affecting the impact toughness and the impact fracture mechanism were analyzed. The results show that the normalizing treatment with the heating temperature not exceeding 1000 ℃ can refine the skeleton and increase the primary ferrite content, so as to ensure the higher strength level, improve the impact toughness and reduce the ductile-brittle transition temperature. Analysis of ferrite content is the main influencing factor of impact toughness. With the coarsening of primary austenite grains and the reduction of proeutectoid ferrite content, the fracture mechanism changes from strain-induced quasi-cleavage fracture to stress-induced cleavage fracture. The impact energy is controlled by the crack propagation function to be cracked Form power control.