A comparative study of the mechanical properties of 6061-T6 GMA welds obtained by the indirect electric arc (IEA) and the modified indirect electric arc (MIEA)

Plates of a 6061-T6 aluminium alloy with 12.7 mm in thickness were welded with the gas metal arc welding process (GMAW) using three different joint designs; a single V groove butt joint, the indirect electric arc (IEA) joint and the modified indirect electric arc joint (MIEA). The later is a modification of the IEA joint which requires preheating of the plates prior welding to achieve full penetration with an ER-4043 filler wire. The single V groove joint was welded at ambient temperature with four welding passes whereas the IEA and MIEA joints were welded with preheating at 50, 100 and 150 °C in a sole pass. A comparison of the macrostructural characteristics and mechanical performance showed that joining this alloy is feasible with the different joint geometries. However, the thermal affection for the single V groove joint is quite large leading to a severely overage zone in the base metal that profoundly affects the mechanical strength of the welded joint. This effect was less dramatic for the IEA and MIEA joints due to lower heat inputs, but only the mechanical strength of the MIEA weld was above the permissible values indicated by international standards for welded joints of the 6061-T6 alloy.