预拉伸对铝合金焊接残余应力和变形的影响

在预拉伸应力作用下，进行了厚度为4mm的5A05铝合金试板的焊接，焊后残余应力及变形的测定结果表明．预拉伸焊接法可有效减小铝合金薄板焊后的纵向残余应力、纵向挠曲变形和平面变形。在弹性应力范由内，随着预应力的增大，试板的残余应力峰值、纵向挠曲变形及平面变形均逐渐减小。分析认为，预拉伸应力部分抵消了焊接区热膨胀产生的压缩应力，从而减小了压缩塑性变形，进而减小了冷却时焊接区域的拉伸应力水平，相应地远离焊缝区域的压缩应力也随之减小。

Effect of Pre-tension on Welding Residual Stresses and Distortions of Aluminum Alloy

The 5A05 aluminum plates with 4 mm thickness were welded under pre-tension stresses. Measurement results show that the welding residual stresses and the longitudinal warp distortion near the weld and flat distortion of the weldments can be reduced effectively when welded under pre-tension stresses. And the greater the pre-tension stresses at the range of elasticity are, the smaller the residual stresses and distortions. It is considered that pre-tension stress counteract the compression stress in welding zone generated by thermal expansion, consequently reduce the compression plastic deformation, and depress the tension stress in welding zone when cooling down, and accordingly minish the compression stresses far from the welding zone.