Effect of defocusing amount on morphology and microstructure of 8-mm-thick Ti-6Al-4 V laser deep penetration welded joint

• Published in: International journal of advanced manufacturing technology 2022-03, Vol.119 (5-6), p.3747-3756
• Main Authors: Gao, Qiyu, Bu, Hengchang, Ling, Wanli, Zhan, Xiaohong, Shen, Honglie
• Format: Article
• Language: English
• Subjects: CAE) and Design; Computer-Aided Engineering (CAD; Defocusing; Engineering; Grain size; Heat affected zone; Industrial and Production Engineering; Laser beam welding; Lasers; Mechanical Engineering; Media Management; Microstructure; Morphology; Original Article; Penetration; Pore formation; Titanium; Vanadium; Welded joints
• ISSN: 0268-3768; 1433-3015
• DOI: 10.1007/s00170-021-08450-z

Laser defocusing amount during laser deep penetration welding results in dissimilar welding morphology and microstructure, which in turn initiates a shift in grain size and pore formation. In this paper, the butt structures of Ti-6Al-4 V alloys with a thickness of 8 mm are successfully joined by the laser deep penetration welding process. The macromorphology and microstructures of the welded joints are investigated at three different defocusing amount combinations. The experimental results showed that the positive and negative defocusing amount had a great influence on the weld width, and then affected the size and number of grains in the weld bead and heat-affected zone. Moreover, the pores were concentrated near the fusion line, which were closely related to Al element evaporation.