Characterization of Laser brazed joints Vis a Vis conventional BIW joining methods

In recent years, there has been a rapid growing demand for laser brazing in the transportation industry for automotive-Body in White (BIW) steel sheet assembly. Implementation of laser brazing is aimed primarily to improve productivity, quality of joints and cost. Laser brazing works by filling the opening amongst two substrates by melting the filler wire with the help of laser beam (used as a heat source), whereas in conventional resistance spot welding, contacting metal surface points are joined by the heat obtained from resistance to electric current. Body in White (BIW) is essentially a welded metal structure which is meant to provide durability and crashworthiness to the vehicle and is conventionally assembled using resistance spot welding process. The BIW structure comprises of various steel grades having varying thicknesses, composition, microstructure and mechanical properties. Laser brazing as a joining method was introduced as an alternative to resistance spot welding for assembling certain BIW components (e.g. roof). Physical and mechanical characterization is undertaken for laser brazed joints Vis a Vis resistance spot welding. The aim of this study is to determine the method of testing, specimen geometry, mechanical characteristics (comprising of uniaxial tensile strength & hardness profile) and physical characteristics (comprising of micrographs, depth of penetration, depth of penetration, braze length etc.), for the laser brazed joints and undertake a comparative analysis w.r.t resistance spot welding. The future scope of work includes characterization of the corrosion and paintability behavior of the laser brazed joints.