预时效制度对Al-Mg-Si-Cu合金组织与性能的影响

通过TEM及拉伸性能试验研究了较宽的预时效工艺参数(80~200℃,2~30 m in)下,A l-Mg-S i-Cu合金的组织及性能演变规律。研究表明:实验合金在80~200℃进行预时效处理,能够抑制自然时效的不利影响。在80℃×(2~30 m in)进行预时效后,材料烘烤硬化效应提高有限;在120~160℃预时效5~10 m in后,材料的烘烤硬化效应得到较大的提高,且材料烤漆前的屈服强度较低,有利于冲压成形;在更高的温度如200℃进行预时效时,材料烤漆前屈服强度过高,但此时材料的烘烤硬化效应提高尤为显著。T4P下GP区的尺寸对材料烘烤硬化效应的提高至关重要。

Effect of pre-aging treatment on microstructure and properties of an Al-Mg-Si-Cu alloy

Effect of pre-aging process parameters on microstructure and mechanical properties of an Al-Mg-Si-Cu alloy were investigated using TEM and tensile test. The results show that the pre-aging treatments at 80-200℃ can suppress the negative effect of natural aging on subsequent paint-bake cycle. After pre-aging at 80℃ for 2-30 min,the improvement of strength for the alloy after paint-bake treatment is not significant. Meanwhile,the alloy pre-aged at 120 to 160℃ for 5 to lO min exhibits a relative low yield strength and good ductility in T4P state,which is favorable for stamping,and after the paint-bake treatments the high strength of the alloy is obtained. The strength of the alloy at T4P and T8X conditions is further increased when it is pre-aged at 200℃ . The size of GP zones at T4P condition has a crucial influence on the improvement of paint-bake reaponse of the alloy.