自然时效及Cu对6061型铝合金塑性的影响

Influence of natural ageing and Cu on the ductility of 6061 Al alloys

采用拉伸试验研究了自然时效及Cu对6061型铝合金塑性的影响,并通过加工硬化及应变速率硬化理论解释了合金塑性变化规律。研究结果表明:随着自然时效的进行,合金的强度持续上升,自然时效1 d后趋于稳定。与此同时,随着自然时效的进行,基体中的溶质原子浓度逐渐下降,从而造成加工硬化能力的下降,因此合金的均匀塑性及总伸长率逐步下降。基体中溶质原子及空位浓度的下降也减小了动态应变时效对应变速率硬化不良的影响,因此合金的后均匀塑性逐步增大;添加Cu后,由于提高了初始加工硬化速率,因此合金的均匀塑性得到了提高。但由于Cu的添加增大了动态应变时效对应变速率硬化的负贡献,因此造成后均匀塑性的下降。

Influence of natural ageing and Cu on the ductility of 6061 Al alloys was investigated with tensile testing.The variation of alloy ductility was explained through the work hardening and strain-rate hardening capabilities theory.The results show that with natural ageing time increasing the strength increases.After one day of natural ageing,the strength tends to be stable.Meanwhile,as natural ageing proceeds,the depletion of solute in the matrix leads to the decrease of the work hardening capability.This results in the decrease in the uniform ductility and total elongation.The depletion of solutes in the matrix and vacancy concentration also cause the decrease of negative contribution of dynamic strain ageing to the strain rate hardening capability.Therefore,the post-uniform ductility tends to increase with natural ageing.The addition of Cu speeds up the initial work hardening rate,and thus improves uniform ductility.Cu additions also increases the negative contribution of dynamic strain ageing to the strain rate hardening capability,which,in turn,decreases the post-uniform ductility.