Residual stresses in laser welded aluminium plate by use of ultrasonic and optical methods

With the wide application of aluminium alloys to the automotive, aerospace and other industries, laser welding has become a critical joining technique for aluminium alloys. In this paper, two techniques have been used to measure the non-uniform residual stresses in laser-welded aluminium alloys, i.e. the Lcr ultrasonic technique and the moiré interferometry incremental hole-drilling (MIIHD) method. The non-uniform residual stress distribution in the transverse direction in a laser welded sample was obtained using the Lcr ultrasonic method. The non-uniform in-depth and in-plane residual stresses in the weld center and heat-affected zone were measured using MIIHD. The experimental results showed that these two methods are effective for non-uniform residual stresses problems such as welding.