Effect of Dwell Time on Joint Interface Microstructure and Strength of Dissimilar Friction Stir Spot-Welded Al-5083 and St-12 Alloy Sheets

Mechanical, electrochemical and structural characteristics of friction stir spot welds of aluminium alloy 6063

“…It was concluded that a large plunge from the high dwell time formed preliminary cracks in the intermetallic compounds which can be studied as weld defects. Fereiduni et al [23] concentrated on the effect of the microstructure observation with its intermetallic phases and joint interface and the dwell time in order to describe the variance of weld strength, conducting FSSW on AA 5083 and steel-12 sheets. The dwell time was varied and was seen to produce stronger joints.…”

“…The SZ shows recrystallized equiaxed grains which are smaller than in the as-received material; which correlates to the hardness property, having the highest hardness [23,17]. The HAZ has coarse grains due to the frictional heat applied and which is generally found closer to the weld centre and has black characteristics of dark dots [31] in the microstructure, having the lowest hardness [17,23].…”

“…Fereiduni et al [23] determined how the dwell time and the microstructural observations of FSSW of AA 5083 and steel À12 sheets are affected. Hamzah et al [17] studied how the pin shape and the rotation speed affected the mechanical properties and microstructural evolution of FSSW 6061.…”

Interfacial bonding mechanism in Al/coated steel dissimilar refill friction stir spot welds

“…Conventional friction stir spot welding (FSSW) is a relatively new solid-state joining technology, which is a natural alternative to fusion welding due to that it avoids the problems of solidification and liquation cracking [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Mazda has used conventional FSSW to join Al alloy to coated steels in aluminum trunk lid [27], acceptable weld strength was achieved although keyhole significantly decreased effective bonded area [11][12][13][14][15].…”

“…Conventional friction stir spot welding (FSSW) is a relatively new solid-state joining technology, which is a natural alternative to fusion welding due to that it avoids the problems of solidification and liquation cracking [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Mazda has used conventional FSSW to join Al alloy to coated steels in aluminum trunk lid [27], acceptable weld strength was achieved although keyhole significantly decreased effective bonded area [11][12][13][14][15]. There are three main approaches of joining Al alloy to steel by conventional FSSW: (i) directly joining Al to uncoated steel through the formation of IMCs while avoiding plunging the tool pin into bottom steels [11][12][13][14][15][16], (ii) mechanical interlocking by displacing the bottom steel into the Al sheet [17][18][19][20][21][22][23], and (iii) adoption of coatings on steels to promote the interfacial bonding [24][25][26][27]…”