脉冲电流对6016-T4铝合金板材力学性能的影响

为研究在电流辅助成形时脉冲电流的电流密度、占空比和脉冲频率3个因素对6016-T4铝合金板材力学性能的影响规律,设计了3因素5水平的正交实验。实验表明,对6016-T4铝合金力学性能影响的主次因素是:电流密度>占空比>脉冲频率。在此基础上,选用主次2个因素,即电流密度和脉冲频率,使用控制变量法进行进一步的实验研究。实验结果表明,电流密度对6016-T4铝合金力学性能影响较大,改变电流密度的同时带来了明显的焦耳热效应,该效应对材料有明显的软化作用,降低了材料的流动应力,但是,同时也降低了铝合金板的伸长率,这是因为过大的电流密度加剧了试样的主应变演化,进而促进了试样的断裂。而脉冲频率的变化对6016-T4铝合金板材的力学性能影响很小,这也印证了正交实验的结论。

Influence of pulse current on mechanical properties for 6016-T4 aluminum alloy sheet

In order to study the influences of three factors of pulse current density,duty cycle and pulse frequency on the mechanical properties of 6016-T4 aluminum alloy sheet in current assisted forming,an orthogonal experiment was designed with three factors and five levels. The experimental results show that the main and the secondary factors influencing the mechanical properties of 6016-T4 aluminum alloy are current density > duty cycle > pulse frequency. On this basis,two factors of current density and pulse frequency were selected for further experimental research with control variable method. The experimental results show that the current density has a great influence on the mechanical properties of 6016-T4 aluminum alloy. The change of current density brings about an obvious joule thermal effect,which has a significant softening effect on the material and reduces the flow stress of the material. The elongation of the aluminum alloy sheet is also reduced at the same time,because excessive current density aggravates the evolution of the main strain for specimens and promots the fracture of the specimens. However,the change of pulse frequency has little effect on the mechanical properties of 6016-T4 aluminum alloy sheet to confirm the conclusion of orthogonal experiment.