Microstructure and heat treatment response of 2014-T6 GMAW welds obtained with a novel modified indirect electric arc joint

In this study, plates of a 2014-T6 aluminium alloy with a thickness of 12.7 mm were welded with the GMAW process using a single V groove joint and a novel modified indirect electric arc (MIEA) joint. Whilst the later enables welding of the plates in a single pass with a non-heat treatable ER4043 electrode, the first needs a multi-pass procedure. These joint designs were compared in terms of microstructure and mechanical behavior in the as-welded and post weld heat treated (PWHT) conditions. It was found that the single V groove joint failed in the heat affected zone (HAZ) with a tensile strength of 159 MPa whereas the novel joint failed in the weld metal with values rangingfrom 257 to 240 MPa depending on the preheating temperature of the joint. PWHT of the welds increased the tensile strength of the single V groove joint to 268 MPa and to 396-343 MPa for the MIEA joint with failure occurring consistently in the weld metal. As the mechanical strength of the ER4043 electrode (190 MPa) is well below these values, the results are discussed in terms of dilution ratios, microstructure and microhardness profiles across transverse sections of the welds.