Optimization of process parameters of friction stir welded joints of dissimilar aluminum alloy by response surface methodology

Abstract

Aluminum and its alloys are lightweight, affordable, high-strength materials that find extensive use in shipbuilding, automotive, construction, aerospace, and other industrial fields. They are also resistant to corrosion. There is a requirement to join components manufactured of various aluminum alloys, namely AA6061 and AA7475, in applications like the aerospace, marine, and automotive sectors. Friction stir welding (FSW) is utilized in this study to join dissimilar plates consisting of aluminum alloys 6061 and 7475. On the tensile strength and percentage elongation of the welded joints, the impact of changing the tool pin profile, tool rotation speed, tool feed rate, and tool tilt angle has been studied. The empirical relationship between the output responses and input parameters was developed, and the perceived optimal values of UTS, % strain and micro hardness at SZ were 205.23 MPa, 16.43 %, and 81.05 HV, respectively. The optimal TS, TRS, and tilt angle values were 87.42 mmmin-1, 783.92 rev/m, and 0.48°, respectively. Due to DRX, the microstructure in the weld SZ was characterized by a very fine grain structure. Because of the decreased hardness, the grain sizes in HAZ and TMAZ are virtually comparable, and they discovered coarse grain structure and uneven temperature distribution in that region. When the TRS and TS increase, the grain size decreases in the SZ