Thermodynamic analysis of interfacial reaction by pulsed DE-GMAW for aluminum-steel dissimilar metals

ER5356 aluminum alloy wire was welded on galvanized steel sheet by pulsed DE-GMAW process.The best weld morphology was obtained by adjusting the welding parameters.The results indicate that fusion-brazing between aluminum alloy and galvanized steel was achieved by pulsed DE-GMAW process.The microstructure of the interface in joint was observed and analyzed with SEM and EDS,and Fe₂Al₅ and FeAl₃ intermetallic compound layers formed in the interface.The Gibbs free energies of Fe₂Al₅ and FeAl₃ intermetallic compounds were calculated with Thermo-Calc software,and it was found that the Gibbs free energy of Fe₂Al₅ was smaller than that of FeAl₃ at high temperature,but the Gibbs free energy of FeAl₃ was smaller than that of Fe₂Al₅ at low temperature.The results show that Fe₂Al₅ intermetallic compound formed first during welding,and subsequently FeAl₃ intermetallic compound formed and precipitated upon cooling.