【摘要】 本文采用电子显微断口分析方法,对20SiMn2MoV低碳马氏体钢,45Cr和T12钢淬火不同回火态和34CrNi3Mo电站大锻件用铜的疲劳裂纹萌生与扩展机制进行了研究.并着重在材料的不同强塑配合引起断裂机制变化的关系中做了探讨;总结了三个区之间机制转变的条件;给出了较初步的疲劳断裂机制图;从材料强度方面提出了各阶段的主要控制因素,从而为改善材料疲劳抗力提供了一些依据.更多还原

【Abstract】 A study is made of the fatigue crack initiation and propagation mechanisms in 20SiMn2MoV, 34CrNi3Mo, 45Cr low alloy structural steels and T12 tool steel using electron fractography, the 45Cr and T12 haying been treated to different tempering conditions.In region I with Iow ⊿K values, the fatigue crack initiation and propagation mechanisms may change from slip-plane decoherence to intergranular fracture with increasing yield strength, those mechanisms are sensitive to microscopic structures.In region II with medium ⊿K values, the crack propagation mechanism is the formation of striations in medium and low strength steels.In region III with high ⊿K values, the crack propagation mechanism is of a mixed striation and static fracture type.This paper discusses the relation between the change in the fracture mechanisms and that is material strength. It summarizes the conditions for fracture mechanism transition in the three regions, where for a fatigue fracture mechanism map is obtained.更多还原