The effect of heat treatment on mechanical properties of pulsed Nd:YAG welded thin Ti6Al4V

Abstract

Pulsed Nd:YAG has been adopted successfully in welding process of thin (0.7 mm) Ti6Al4V. Laser welding of such thin sheet requires a small focal spot, good laser beam quality and fast travel speed, since too much heat generation can cause distortion for thin sheet weld. The microstructures of Ti6Al4V were complex and strongly affected the mechanical properties. These structures include: a䠭artensite, metastable ߬ Widmanst䴴en, bimodal, lamellar and equiaxed microstructure. Bimodal and Widmanst䴴en structures exhibit a good-balance between strength and ductility. The microstructure of pulsed Nd:YAG welded Ti6Al4V was primarily a䠭artensite, which showed the lowest ductility but not significantly high strength. A heat treatment at 950 followed by furnace cooling can transform the microstructure in the weld from a䠭artensite structure into Widmanst䴴en structure.