Mechanical behavior and microstructure of dissimilar aluminium/titanium rotary friction weld joints

Abstract

The objective of this study is to employ the rotary friction welding (RFW) technique to join dissimilar materials AA2024/Ti6Al4V. The experimental design encompasses the manipulation of RFW process input parameters, using the Taguchi L9 array methodology. The collected data underwent thorough analysis, aimed at determining the ultimate tensile strength (UTS) of the resultant weld joint. The prime focus rested on ascertaining optimal RFW conditions that could effectively maximize the UTS. Through the use of statistical analysis of variance (ANOVA), the process parameter of utmost significance was identified. The outcomes of this investigation were harnessed to formulate regression model pertaining to the UTS of the RFW joint. Furthermore, fatigue tests were executed to exhibit the cyclic behavior of the dissimilar welds, yielding a comprehensive Wöhler curve that facilitated the estimation of specimen longevity under stress cycles. In addition, microscopic observations were carried out to discern the microstructural evolution and the quality of the weld joint. Finally, scanning electron microscopy (SEM) analysis was conducted to investigate damage micro-mechanisms specimens. The results show that using a rotational speed of 1290 rpm, friction pressure of 6 MPa for 6.3 s, and forging pressure of 6 MPa for 8 s leads to an improvement in the UTS value up to 424.31 MPa, corresponding to a joint efficiency of 90.46%.