Effect of additional heating on corrosion of dissimilar friction stir welded aluminum alloys

Abstract

In the present work, aluminum alloys AA2014-T6, AA6061-T6 and AA7075-T651 are used to fabricate two different dissimilar friction stir welds of AA6061-AA7075, and AA6061-AA2014 using a threaded tool pin with three flat faces at tool rotational speed of 1200 rpm, weld speed 98 mm/min and employing additional secondary heating. Additional heating is provided using butane gas torch which principally expedites better material mixing supplementarily resulted in increased corrosion resistance. The higher working temperature provides steeper cooling rates necessary for grain refinement and additional breakdown or dissolution of corrosion susceptible particulates. The joints fabricated sustained corrosive environments for adequate duration and ultimate tensile strength of the joints are retained after 14 days of immersion in corrosive saline solution. AA6061 experienced pitting as well as intergranular corrosion, AA2014 shows pitting and AA7075 exhibited exfoliation corrosion. The fracture morphology shows substantial size dimples indicating the loss in ductility for all the joints due to the after effects of heating.