TC4钛合金激光焊接接头超塑性变形过程熔合区中组织演变研究

Microstructure Evolution of Ti-6Al-4V Laser Weld Joint Fusion Zone in Superplastic Deformation Process

通过观察高温拉伸中TC4钛合金激光焊接接头的熔合区的显微组织,研究了熔合区的组织演变规律。变形之初,熔合区的组织由一层宽度窄界限明确的短小片层组织组成;随着变形量的增加,熔合区的组织、热影响区、焊缝三者的组织相互交织渗透,熔合区的宽度增加;当试样拉伸到断裂时试样组织基本完全等轴化,熔合区为均匀的等轴晶粒。总体来讲,熔合区的整个变形过程中可分为以下3个进程:一次转变、二次转变、组织的均匀化。

Microstructure evolution of Ti -6Al -4V laser weld joint fusion zone was studied by observing the microstructure during the superplastic deformation process. The results suggested that the fusion zone microstructure first was composed of short lamellars. With the increase of deformation, the microstructure of fusion zone, heat - affected zone and weld was mingle penetrated and the width of the fusion zone was increased. When the sample was breaking, the sample tissue was completely equiaxed and the grain of fusion zone was evenly equiaxed. The deformation process of the fusion zone can be divided into the following three processes： the first microstructure transformation, the second microstructure transformation and the microstructure homogenization.