Experimental Investigation on the Laser Welding Characteristics of 6061-T6 Aluminum Alloy Sheets

Abstract

Generally, welding is an indispensable process in the assembly of automobile body parts, while resistance spot welding is applied in many cases. However, an efficient welding technique is necessary because an aluminum alloy has lower resistance and higher thermal conductivity than steel. Based on this point of view, laser welding has been studied as a new method to obtain stable welding quality and ensure deep penetration with low heat input, regardless of the type of material used. In this study, the lap joint weldability of the Al 6061-T6 thin plate, which is a heat-treated aluminum alloy, was investigated by varying the focus position, including the laser power and welding speed. The main result showed that the sound bead was formed when the power was 2 kW, the welding speed was 2 mpm (meter per minute), the focus position was at −0.8 mm, and the N₂ shielding gas flow rate was at 10 l/min. Also, the strength of the welds under optimum welding condition was 52% compared to the base material. However, the welded part was subjected to ageing heat treatment (170°C, 12 hours), and demonstrated a strength of 295 MPa, which is about 90% of the base metal.