Controlling the Fe-Al intermetallic layer thickness along the joint interface has remained a critical challenge in gas metal arc welding of galvanised steel and aluminium alloys. An attempt is presented here to join galvannealed steel and aluminium alloy sheets using a novel gas metal arc welding process that allows controlled short circuiting to reduce the rate of heat input significantly. The real time current and voltage transients during the process are monitored to estimate the rate of heat input and its influence on the formation of intermetallic phases and layer thickness. The results show that the intermetallic layer thickness can be controlled and good joint strengths can be achieved when the rate of heat input remains lesser than 130 J mm 21 for the typical lap joint configuration considered here.

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Advanced pulsed current gas metal arc based processes are increasingly attempted for the joining of aluminium alloys and galvanised steel sheets. The bead profile and the thickness of the interfacial Fe-Al intermetallic (IMC) layer significantly influence the failure strength of these joints. Although several experimental studies have examined the nature and extent of the IMC phases and consequent joint strength, quantitative efforts to estimate bead profile and the IMC layer thickness as function of process conditions and resulting heat input are scarce. We present here for the first time a coupled theoretical and experimental study to estimate the bead profile and Fe-Al IMC layer thickness for joining of galvannealed steel and aluminium alloy sheets in a typical lap joint configuration. The computed values of bead profile and IMC layer thicknesses are validated with the corresponding experimental results.

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