Laser microwelding of stainless steel and pure aluminum foil

Abstract

Joining of materials, with a strong bearing on the manufacturing industry, has remained an active area of research for decades. The demand for the fabrication of a variety of miniature components has placed more emphasis, in particular, on the welding of thin materials. Welding of thin materials is a challenging task, and more so if they are foils of dissimilar materials, as even a tiny weld flaw invariably can lead to a rapid blemishing of the job. Aluminum with its good thermal and electrical properties, low specific weight, and low cost is often considered a preferred material in many applications. In this communication, the authors present the result of a feasibility study of laser-assisted welding of stainless steel (AISI 304) and pure aluminum foils. A repetitive single-mode nanosecond fiber laser was used to carry out the weld in the lap joint configuration. Welding between the foils was done in the weld brazing mode. Electron microscopy, microhardness measurements, and tensile testing were carried on the weld to evaluate its microstructural and mechanical properties. In the course of welding, stainless steel remained in solid state, while aluminum underwent localized melting over a narrow zone at the interface. The use of very short duration repetitive laser pulses with lower heat input restricted the bulk diffusion of elements across the interface and thereby the generation of the intermetallic compound/second phase with minimum Heat Affected Zone and almost no distortion. This study establishes a nanosecond laser-assisted welding technique as an option for microwelding between stainless steel and aluminum foil.