Influence of process parameters on mechanical and microstructural property of dissimilar friction stir welded joints of armor aluminium alloys AA7039 and AA5083

Abstract

Friction stir welding (FSW) is an innovative, green and energy-efficient solid-state welding process. Which has been resolved the problems of defects related to microstructure and mechanical properties of welding joints of soft materials. FSW is also capable to join dissimilar materials of different melting points together with adequate efficiency and effectiveness. Present research work is an attempt to join the two dissimilar armor grad aluminium alloys i.e. AA7039 and AA5083 by FSW. Both materials are utilized as armor materials in defence. The process parameters such as tool rotation speed (RS), welding speed (WS) and tool tilt angle (TA) were utilized for variation at different five levels for experimentation. The experiments were designed by center composite design (CCD) of response surface methodology (RSM). The fabricated joints were examined for the variation in mechanical properties such as ultimate tensile strength (UTS), yield tensile strength (YTS) and percentage elongation (EL). Effects of the inputs parameters on the variation of the responses were validated by analysis of variance (ANOVA). The obtained results of aforesaid properties were utilized for the optimization of input parameters in the desirability approach. The desirability approach revealed that 1440 RPM of tool rotation, 32.1 welding speed and 2.4 tilt angle as an optimized set of parameters, which can fabricate the joint with 263.02 MPa UTS, 211.90 MPa YTS and 14.7% EL. The results of ANOVA and optimization were also verified by a change in the microstructure of FSWed joints.