Using Gas Metal Arc Welding (GMAW) with AHSS does present some technical hurdles. AHSS are sensitive to heat inputs of GMAW and can potentially suffer from microstructure changes and reductions in mechanical properties. It's a problem made all the worse in the down-gauged sheet made possible by AHSS strength. In his GDIS presentation, Ford's Elliott outlined some of the company's ongoing work to optimize GMAW process variables and weld-line geometry. For example, he identified a number of variables that can increase fatigue life of a lap-welding joint between a 3.4 mm AHSS (DP 600) and a 3.8 mm mild steel. Among the variables are decreasing wire feed speed and travel speed while increasing torch angle, push angle and the contact-to-work-distance.
Take a more comprehensive look at Elliott's study.