Micro welding of aluminium is performed with pulsed laser sources when the heat affected zone has to be minimized. The high reflectivity of aluminum for infrared radiation of Nd:YAG lasers and the pulsed welding process restrict the process efficiency in terms of penetration depth and throughput. In addition, the temperature cycling during the pulsed process increases the risk of heat cracking. In this study, the laser radiation of a pulsed Nd:YAG laser and a pulsed diode laser is superposed to increase the weld penetration and to reduce heat crack formation in Al6082-T6 alloy. The results prove that the superposition extends the process window for crack free welding with an increased weld penetration of up to 25 \%. The superposed diode laser pulse is expected to reduce the cracking susceptibility by increasing the molten volume between the grains in the partially molten zone. This enables better backfilling of intergranular void and reduces the heat crack inducing tensile stress per grain boundary.