预拉伸对7075铝合金中厚板几何精度和力学性能的影响

Effect of pre-stretching on geometric accuracy and mechanical properties of 7075 aluminum alloy plates

以厚度为6 mm的7075铝合金中厚板为对象,开展预拉伸对板材几何精度和力学性能的影响研究.试验表明,当预拉伸量相同时,板材宽厚比越大,回弹后的纵向永久变形率越小;预拉伸对板材的宽向尺寸影响很小,其预拉伸过程近似于纵向延伸、厚向减薄的平面应变状态;通过数据拟合,建立了3种宽厚比中厚板的预拉伸量与其纵向和厚向回弹后永久变形率之间的关系方程;随着纵向永久变形率的增加,预拉伸板时效后的屈服强度和抗拉强度均呈先增加后减少的趋势;在纵向永久变形率为2.0%~2.5%时,预拉伸板的强度性能达到最大值.

The effect of pre-stretching on geometrical accuracy and mechanical properties of 6 mm thick 7075 aluminum alloy plate sheet was studied.The results show that the larger width to thickness ratio of the sheet,the smaller longitudinal permanent deformation after rebound when pre-stretching amount is the same.Pre-stretching has little effect on the width dimension of the plate,and its pre-stretching process is similar to the plane strain state of longitudinal extension and thickness reduction.Through data fitting,the relation equations between the pre-stretching amount and the permanent deformation rate after spring back in longitudinal direction and thickness direction for three kinds of heavy plate with width-to-thickness ratio are established.With the increase of longitudinal permanent deformation rate,the yield strength and tensile strength of the pre-stretched plate after aging show a trend of increasing first and then decreasing.When the longitudinal permanent deformation rate is 2%~2.5%,the strength performance of the pre-stretched plate reaches the maximum.