桥用铝合金的低周疲劳亚结构

在应变幅控制下，研究了桥用铝合金在两种热处理工艺下的循环特性及其微观结构的变化。结果表明：在应变幅为△ε＿ｔ／２＝０．４％～１．０％范围内，热处理工艺Ⅰ合金循环软硬化现象不明显，热处理工艺Ⅱ合金表现为循环硬化特性。ＴＥＭ分析表明，不同热处理工艺下合金循环断裂时均已形成结构清晰形状完整的胞状位错结构，影响胞结构形成的主要因素可能是层错能、应变幅等，与材料的组织状态没有关系。

FATIGUE SUBSTRUCTURE IN BRIDGE-USING Ai ALLOY DURING LOW CYCLE FATIGUE

The cycle behavior and the substructure change in bridge-using Al alloy at two heat treatments were studied tinder strain contolled low-cycle fatiguing.The results show thatⅠtreated alloy does not have obviously softening or hardening,Ⅱ treated alloy displays evident cycle hardening nder strain controll in the amplitude range of △ε=0.4%～1.0%. Celltular dislocation substructures have formed under TEM after two different alloys fatigued and broke.This microstructure has the cellular characteristic of distinct constructure and completed shape. The main tactors which influence the formation of cellular substructure may be stacking fault energy,strain amplitude etc.,and nothing to do with the heat treated state of the material,