Pulsed Laser Welding of Automotive Advanced High Strength Steels Thin Sheets

Abstract:

The need of cost and weight reduction trend present in the automotive industry lead to the implementation into automotive sector of new materials categorized as Advanced High Strength Steels (AHSS). The use of these materials requires the development of appropriate joining technologies, e.g. pulsed laser welding. The paper presents the results of the development of overlap joints realized by pulsed laser welding technologies of Zn coated AHSS. The statistical influence of the main process parameters was investigated by means of factorial experiment design weighted towards the shear strength results. The influence of laser pulse peak power, the joint gap, the travel speed and the position of the focal point were investigated for three types of AHSS with different thicknesses. The results reveled that the base material thickness influences the importance of the investigated process parameters with impact onto the maximum obtainable shear strength values. Thus, with the thinnest plates, the travel speed is the most important process parameters then the joint gap starts to have also an important role, and for the thicker plates the joint gap becomes the most important influence factor – a phenomena which can be related to the Zn vapour expulsion.