预时效对车身用6016铝合金烘烤硬化性能的影响

Effect of pre-aging on bake hardening properties of 6016 aluminum alloy for car body

采用硬度测试、拉伸试验和透射电镜等手段研究了不同预时效处理对6016铝合金烘烤前后微观组织和力学性能的影响。结果表明:6016铝合金具有较强的自然时效硬化能力,自然时效24 h的6016铝硬度比固溶态合金硬度增加了45.6%。自然时效超过24 h以后,合金硬度值变化不大。通过预时效处理可以显著提高6016铝合金的烘烤硬化效果。经550℃×30 min固溶+160℃×10 min预时效处理后,6016铝合金规定塑性延伸强度为131.4 MPa,伸长率为24.7%。再经175℃×30 min烘烤后合金规定塑性延伸强度达到199.5 MPa,烘烤硬化值(BH)为68.1 MPa,此工艺为6016铝合金车身板最佳的热处理工艺。

Effects of different pre-aging treatments on microstructure and mechanical properties of 6016 aluminum alloy before and after baking were studied by means of hardness test,tensile test and transmission electron microscope.The results show that 6016 aluminum alloy has a strong ability of hardening by natural aging.The hardness of 6016 aluminum alloy after 24 h of natural aging is 45.6%higher than that of solid solution alloy.But after prolonged natural aging for more than 24 h,the hardness of the alloy has little change.The bake hardening effect of 6016 aluminum alloy can be improved by pre-aging treatment.After the pre aging with the process of heating at 550℃for 30 min solution and aging at 160℃for 10 min,the yield strength and elongation of 6016 aluminum alloy are 131.4 MPa and 24.7%,respectively,then baking at 175℃for 30 min,the yield strength of the alloy reaches 199.5 MPa,and the bake hardening value(BH)is 68.1 MPa,which is an ideal heat treatment process for 6016 aluminum alloy panel.