2A12铝合金时效成形的微观组织和力学性能

对2A12铝合金进行时效成形和人工时效的对比实验,考察时效成形对其微观组织和力学性能的影响。结果表明：与人工时效相比,时效成形过程中由于应力的存在,使得合金在时效成形后晶粒被进一步压扁、拉长,沉淀相由取向随机分布的点状变为具有一定方向性的长条状,同时其位错形态由位错圈或蜷线位错向长直态位错转变。时效成形后,合金的拉伸性能、断裂韧性均比人工时效时的略有降低,疲劳裂纹扩展速率却有所提高。

Microstructure and mechanical properties of 2A12 aluminum alloy after age forming

The comparative experiments of age forming and artificial aging of 2A12 aluminum alloy were carried out. The effect of the age forming on the microstructure and mechanical properties was investigated. The results demonstrate that the grains are further squashed and elongated compared with artificial aging due to the existence of the applied stress during the age forming. Meanwhile, the precipitated phases change from circle shape with random orientation of age forming to long strip shape with uniform orientation of artificial aging. The dislocation configuration in samples changes from ring dislocation or helical dislocation of the artificial aging to long and straight dislocation of the age forming. Otherwise, age forming slightly reduces the tensile properties and fracture toughness of the alloy and enhances its fatigue crack growth rate.