热处理2024-O铝合金在自然时效下的拉伸性能及断口形貌演变

Effect of natural aging time on tensile properties and fracture of heat-treated AA2024-O Al-alloy

摘要:

本文研究了时效时间对热处理后的2024-O铝合金试件的拉伸性能及断口影响。采用室温拉伸方法，研究了2024-O态铝合金经过热处理后不同时效时间试件的应力-应变曲线、屈服强度、抗拉强度，建立了能够预测应力的本构方程，并且通过观察断口，分析了不同时效时间对材料组织的影响。试验结果表明：随着时效时间的延长，试件逐渐强化，到某一时刻达到峰值，屈服强度、抗拉强度下降；应用SEM扫面电镜观察到断口处有大量韧窝，为韧性断裂，而且随着自然时效时间增长，试件断口的韧窝越来越少，塑性越来越差；建立了2024铝合金在自然时效下强化的本构方程,该模型能够较好地预测材料在自然时效下的应力。

Abstract:

The effect of natural aging time on tensile properties and fracture of the heat-treated AA2024-O Al-alloy was investigated. The stress-strain curves, the yield strength and the tensile strength of the specimens with different natural aging time were obtained by carrying out tensile test at room temperature. The constitutive equation that could predict the stress was established. The effect of natural aging time on the material microstructure was analyzed by observing the fracture. The results of the experiment demonstrated that the specimens were gradually strengthened to a certain point, and then the yield stress and the ultimate tensile strength decreased until the material reached a stable state. There were many dimples distributed on the fracture surface that was observed by SEM, so the fracture surfaces were thought to be a ductile fracture. Despite natural aging during long periods, the specimens of dimples became fewer and the plasticity worsened. A series of phenomenological functions were presented for establishing the constitutive equation of AA2024-O Al-alloy strengthened. The model could predict the stress of the naturally aged material.