咬边缺陷对TC4钛合金激光焊接头静力拉伸形变特征的影响

通过对静力拉伸常规试验时进行同步的红外热像测量，对存在咬边缺陷的TC4钛合金焊缝试样和经激光双面修饰焊试样的拉伸过程和结果进行研究.结果表明，屈服现象都首先发生在焊缝区域，但是咬边程度对焊缝试样开始产生屈服现象的应力和应变具有影响，对塑性变形行为影响更大.在咬边小于一定值时，大塑性变形会发生在母材区域，其塑性指标与母材相当；咬边较大时，塑性变形集中在焊缝及其附近区域且快速断裂.而经双面修饰焊的试样，初始屈服现象不再集中在焊缝区域，而是同时发生在焊缝和母材处，塑性变形主要发生在母材区域，与母材相似.

Effect of undercut defect on deformation behavior TC4 titanium alloy laser welded butt joint under static tensile loading

By measuring and analyzing infrared thermal image of the specimen in static load tensile test process, it was studied that the influence of the undercut defects and double-sided dressing method on the deformation behavior of the laser welded joint specimens of TC4 titanium alloy. The results showed that for the unmodified specimens, the yield phenomenon occurs first in the region of the joint, but the undercut value has an effect on the stress and strain of starting to yield phenomenon, and a great effect on the plastic deformation behavior. When the undercut is less than a certain value, the large plastic deformation occurs in the base metal region and the plasticity of the specimen is comparable to that of the base metal, but the larger undercut defect results in a concentrated plastic deformation in the joint region and rapidly failed in this region. But the double-sided dressing specimen is significantly different. The physical yield is no longer concentrated in the joint region, but at the same time occurs in the several regions including joint and the base metal. And the plastic deformation mainly occurs in the base material area, similar to that of the base material.