时效工艺对汽车用6061铝合金型材压溃性能的影响

Effect of Process State on Crushing Properties of 6061 Aluminum Alloy Profiles for Automobile

本研究采用电子万能试验机、扫描电镜等手段研究了不同时效温度(120~220℃)对汽车用6061铝合金型材塑性变形行为的影响。结果表明:当时效温度为120℃时,材料具有约22%的综合延伸率(A50),其中均匀延伸率(Ag)为20%,表现出显著的韧性断裂特征,且断口形貌中存在小部分大而深的韧窝。而当时效温度为160~180℃时,材料强度升高的同时其延伸率(A50和Ag)逐渐降低至9%以下,断口韧窝形貌特征小而浅。随着时效温度的进一步升高,材料的综合延伸率逐渐回升,而均匀延伸率则趋于稳定,两延伸率差值显著变大,拉伸试样逐渐出现强烈的颈缩现象,断口形貌则以大而深的韧窝为主。虽然高均匀延伸率的欠时效试样与出现强烈颈缩的过时效试样都表现出良好的压溃性能,但是强颈缩试样更优。

In this paper,the effect of aging temperature(120—220℃)on the plastic deformation behavior of 6061 aluminum alloy profile for automobile was studied by means of electronic universal testing machine and scanning electron microscope.The results show that the composite elongation(A50)is about 22%and the uniform elongation(Ag)is about 20%after low temperature aging.The samples show the characteristics of ductile fracture,and there are some large and deep dimples in the fracture morphology.However,aging at 160—180℃increased the strength of the material,while its elongation(A50 and Ag)decreased to less than 9%.The dimple morphology of the fracture surface is small and shallow.With the further increase of aging temperature,the comprehensive elongation of the material gradually rises,while the uniform elongation tends to be stable.The difference between the two kinds of elongation increased significantly.The tensile specimen shows a strong necking phenomenon,and its fracture morphology is dominated by large and deep dimples.Although the high uniform elongation sample and the strong necking sample show good crushing performance,the strong necking sample is better.