Comparison of continuous and pulsed wave lasers in keyhole welding of stainless-steel to aluminium

Abstract

A continuous wave (CW) and a nanosecond pulsed wave (PW) lasers were used to join 1-mm thick sheets of SS304L (SS) austenitic stainless-steel to AA5251 (Al) aluminium alloy in an overlap joint configuration. The weld shape (penetration depth and width), intermetallic compounds concentration, weld quality (cracking and porosity) and mechanical strength were correlated with the process energy and compared between each laser temporal mode. Successful CW joints were produced with the SS sheet on top of the Al, but the opposite configuration revealed to be impossible for the range of parameters tested. The PW joints were successful with the Al sheet on top of SS, but all the joints cracked at the interface when the opposite configuration was used. The mechanical tests showed that even though it is possible to achieve higher tensile shear load in CW welds due to the larger bonding area, the tensile shear strength revealed to be almost 5 × higher for PW welds at similar applied energy.

Remote Laser Welding of Zn Coated If Steel and 1050 Aluminium Alloy: Processing, Microstructure and Mechanical Properties

“…Some of the cracks may initiate through solidification cracking and at later stages propagate through several grains or IMCs. In comparison to other recent studies [23,24,41,42,45], this study has produced Steel-Al dissimilar metal welds with very little to minimal cracking with the conduction mode RLW technique. 6.…”