钛合金针状焊缝组织的超塑性变形机理

钛合金激光焊缝是非理想的针状组织，对其超塑性变形机理的研究可进一步推进钛合金LBW/SPF技术的实际应用，也对材料成形机理的发展具有一定意义.研究结果表明，TC4钛合金激光焊接试样具有良好的超塑性变形能力，在变形过程中，焊缝发生两次重要的组织转变，即针状组织片层化和片层组织等轴化的组织转变.片层组织在应力作用下，通过断裂、解体和等轴化的过程而转变成等轴晶粒.片层断裂的主要机制是动态再结晶和应力挤压作用；片层解体的主要机制是晶界滑动和转动作用，接头组织的塑性流动机理为晶粒滚动和晶界滑动机理.

Superplastic deformation mechanism of acicular weld microstructure of titanium alloy

Laser welding seam of titanium alloy is a non-ideal acicular structure. The research on its superplastic deformation mechanism can promote the application of titanium alloy LBW/SPF technology, and also have benefits of significance to the development of material forming mechanism. The results show that the laser welding of TC4 titanium alloy after welding have good superplastic deformation ability. During the deformation process, two important microstructure changes are taken placed in the weld, that is, the microstructure transformation of the acicular structure lamellae and the lamellar tissue equiaxed. Under the action of stress, the lamellar structure is transformed into equiaxed grains through the process of fracture, disintegration and equiaxed. The dynamic recrystallization and compression is the main mechanism of the lamellar fracture; the mechanism of the lamellar disintegration is grain boundary sliding and rotation, the plastic flow mechanism of the weld joint is grain boundary sliding and rolling mechanism.