Pulsed laser butt welding of AISI 1005 steel thin plates

•Pulse laser welding is successfully employed to join 1.7 mm thick AISI 1005 steel.•Response surface methodology is firstly used to optimize welding parameters.•Optimal parameters lead to defect-free butt joints.•Metallurgical characterisation and mechanical evaluation confirmed welds quality. Pulsed laser welding is a joining process, which takes advantage of the laser energy quality with precise control equipment. Its characteristics allow joining thinner materials with reduced thermal distortion without filler material, fulfilling the industrial interest in this process. In the present work, AISI 1005 steel sheets of 1.7 mm thickness were subjected to different pulse Nd:YAG laser treatments to obtain one side bead-on-plate weld samples and double sided butt welds. Since the quality of the joints is strongly influenced by the process parameters, an experimental design methodology was adopted to define a suitable combination of the laser beam power, pulse duration and spot diameter. The Box-Behnken technique and response surface methodology associated with analyses of defects allowed the determination of the appropriate welding parameters. The microstructure characterisation revealed the melted fusion zones originated from the thermal effect of the overlapped pulses. Additionally, microhardness measurements at fusion zone exhibited higher values than the base material and heat affected zone, due to the hard microconstituents developed. The tensile test performed at samples extracted from double sided laser welds showed good resistance results, fracturing at the base material of joints. The present work demonstrates that pulsed laser welding methodology is suitable to obtain high quality joints of steel thin plates.