Automotive laser welding process set-up by design of experiments for low carbon steels

The master thesis project elaborates results on laser welding of a drive clutch mounted on VT3 punch powertrain engine. The proposed research project consists in the development of a methodology to define the main influent parameters on a laser welding weld bead for a drive clutch. The study will be conducted through a statistical instrument in parallel to a deep metallographic analysis. In particular an experiment will be planned (DOE) in order to define the most influent parameters and it will be intensified afterwards through a GLM analysis. A the same time, metallographic inspections by optical and stereoscopic microscope and NDT inspections by eddy current will be exploited to acquire information on thermally altered areas. The metallographic inspection will be useful to observe and extrapolate data on the weld bead geometry and defects which will be defined as outputs in DOE and GLM. The presence of defects will be studied in relation to the material chemistry focusing the attention on different type of observed defects through the instruments mentioned above, SEM and profilometer microscope. Moreover, problems related to low carbon steels weldability will be discussed making observations about the DD steel microscopic structure after the experimental welding process. Based on metallographic observations and numerical statistical data, the developed method justifies the presence of defects in weld beads and makes considerations on the influence of working conditions on geometric weld beads parameters.