Effects of dynamic cooling pre-aging treatment on mechanical properties and paint-bake hardening behavior of Al-Mg-Si alloy automotive sheets  

动态降温预时效处理对Al-Mg-Si合金汽车板力学性能和烘烤硬化行为的影响

作　　者：GAO Guan-jun LI Xi-wu YAN Li-zhen XIONG Bai-qing LI Zhi-hui ZHANG Yong-an WEN Kai LI Ya-nan 高冠军;李锡武;闫丽珍;熊柏青;李志辉;张永安;温凯;李亚楠(State Key Laboratory of Non-ferrous Metals and Processes,GRINM Group Co.,Ltd.,Beijing 100088,China;GRIMAT Engineering Institute Co.,Ltd.,Beijing 101407,China;General Research Institute for Nonferrous Metals,Beijing 100088,China)

机构地区：[1]State Key Laboratory of Non-ferrous Metals and Processes,GRINM Group Co.,Ltd.,Beijing 100088,China [2]GRIMAT Engineering Institute Co.,Ltd.,Beijing 101407,China [3]General Research Institute for Nonferrous Metals,Beijing 100088,China

出　　处：《Journal of Central South University》2022年第3期950-959,共10页中南大学学报（英文版）

基　　金：Project(2020YFF0218200) supported by the National Key R&D Program of China。

摘　　要：In the industrial production, the dynamic cooling pre-aging treatment was employed to replace the isothermal pre-aging during the continuous heat treatment production of Al-Mg-Si alloy automotive sheets. The effects of dynamic cooling pre-aging treatment on mechanical properties and paint-bake hardening behavior of an Al-Mg-Si alloy sheet are proposed in this study. The scanning electron microscopy, transmission electron microscopy, tensile test, Vickers hardness test, and differential scanning calorimetry were conducted for the purpose. It was found that the dynamic cooling pre-aging treatment at low temperature region led to the decreasing of cluster II, resulting in the deterioration of the ability of the paint-bake hardening. With the increase of the cooling pre-aging temperature, the increasing of cluster II effectively improved the stability against natural aging and the paint-bake hardening ability. The optimized dynamic cooling pre-aging temperature was ~150 ℃. In this condition, the hardness increase of the alloy sheet with pre-aging treatment is low during storage at room temperature. The high yield strength increment is obtained after paint-bake hardening.在工业化生产的Al-Mg-Si合金汽车板连续热处理过程中,铝加工厂采用降温预时效处理来代替等温预时效处理工艺。因此,降温预时效工艺窗口的快速确定与优化具有重要的现实意义。本文通过扫描电镜、透射电镜、拉伸测试、维氏硬度测试以及差式扫描量热分析等技术手段,研究了动态降温预时效处理对Al-Mg-Si合金汽车板力学性能和烘烤硬化行为的影响。结果表明,低温降温预时效处理使得团簇II数量减少,从而导致合金板材烘烤硬化性恶化;随着降温预时效温度的提升,基体中团簇II数量增加,显著提高合金板材的抗自然时效稳定性以及烘烤硬化性。通过对降温预时效工艺的优化,得出最佳降温预时效温度约为150℃,此条件下,合金板材在预时效后的室温停放过程中硬度增长量较低,并且在烘烤硬化过程中获得高屈服强度增量。

关 键 词：Al-Mg-Si alloy mechanical properties paint-bake hardening behavior dynamic cooling pre-aging precipitates 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG156.92[金属学及工艺—金属材料]