6014铝合金板材温拉伸本构方程

Constitutive equations of aluminum alloy 6014 sheet under warm tension

采用DDL50高温电子万能试验机,在变形温度为298~573 K、应变速率为0.0001~0.01 s-1时,针对6014铝合金薄板进行温拉伸实验研究,基于Fields&Backofen本构方程进行修正,建立了6014铝合金的温拉伸本构模型以描述6014铝合金温拉伸时的流变行为。结果表明:相同应变速率下,随着温度升高,6014铝合金的流变应力降低,伸长率先增加后下降,并且当温度为473 K时,伸长率达到最大值。通过断口扫描电镜照片分析了6014铝合金在473和573 K时断裂过程的差异,温度为473 K时,断口韧窝大且深,表现为典型的韧性断裂,而温度为573 K时,韧窝小且浅,表现为脆性断裂,从微观角度解释了不同温度下伸长率的差异。

The warm tension tensile tests of aluminum alloy 6014 sheet were performed at deformation temperatures of 298-573 K with strain rate of 0. 0001-0. 01 s-1 on DDL50 high temperature electronic universal testing machine,and a constitutive equation modified by Fields Backofen equation was established to describe the flow behavior of aluminum alloy 6014 in warm tensile. The results show that under the same strain rate,with the increasing of temperature the flow stress decreases,while the elongation increases firstly and then decreases,and the elongation reaches the highest value at 473 K. Then,the fracture surface was observed by SEM to analyze the difference of fracture process at 473 K and 573 K. The results show that the dimples on fracture are big and deep at 473 K,and the fracture is typical ductile fracture. While the dimples are small and shallow at 573 K,and the fracture is typical brittle fracture. Thus,the difference of elongation at different temperatures is analyzed from microscopic view.