中文摘要：

焊缝材料是一种非均匀材料,其焊缝区、母材区、热影响区具有不同的力学性能.为了能使焊缝材料在工程实践中得到合理应用,对焊缝材料不同区域力学行为进行定量研究变得非常重要.本文采用数字图像相关（DIC）方法对TC4钛合金焊缝在单轴拉伸载荷作用下的变形场进行测量,得到了焊缝材料在不同载荷下不同区域的应变场,3个区域的应变从大到小依次为母材区、焊缝区、热影响区,并且母材区的应变远大于焊缝区和热影响区.母材区具有良好的韧性,其局部失效应变可达30％.同时对加载过程中的变形局部化现象进行了定量测量,焊缝在达到峰值载荷时就已经出现微小的颈缩,峰值载荷时颈缩量仅为0.075 mm,断前一瞬间颈缩量可达0.271 mm.最后对试验系统的误差作了简要分析,验证了DIC方法的可靠性.

英文摘要：

Weld material is a kind of non-uniform material with the weld, parent material and the heat affected zone posses- sing different mechanical properties. It is important that the mechanical features of the diverse zones in a weld material are quantitatively investigated in order to reasonably apply it in engineering. This paper uses digital image correlation （DIC） method to measure the deformation field of a TC4 titanium alloy weld under uniaxial extension loading. The strain fields of dif- ferent areas are obtained under different loads. The parent material zone, weld zone and heat affected zone are each char- acterized by the strain of its area in a descending order. The strain of the parent material zone is found to be much greater than that of other zones. The local failure strain of the parent material can reach 30%, which means the ductility of the par- ent material is fine. Then the transformative localization behavior is measured during the loading process. At the peak load, tiny necking of 0. 075 mm is formed, while necking reaches 0. 271 mm when the specimen fractures. Finally, the error of the test system is also analyzed, from which the reliability of the DIC method is verified.