Effect of Water Cooling on the Performances of Friction Stir Welding Heat-Affected Zone

Effect of backing plate material in friction stir butt and lap welding of 6063-T4 aluminium alloy

“…Separately, softening in HAZs in this case is from the formation of overaged β precipitates, lower dislocation densities from enhanced recovery, and grain coarsening. These results are in line with works of Heinz and Skrotzki [11], Zhang et al [31], and Lee et al [32] who reported loss of hardness in HAZs, experiencing peak temperatures of around 420 o C, from formation of overaged β Mg 2 Si precipitates. The absence of softening in HAZs for 3 mm sheets or 6 mm sheets welded with stainless steel and mild steel backing plate indicates that peak temperatures of about 385 o C or less in HAZs do not result in overaging of these regions for this alloy.…”

“…6 that Fig. 8b and c. This is in line with works of Sato et al [28] and Zhang et al [31] who too observed significantly overaged precipitates in HAZs when peak temperatures in HAZ reach around 420 o C. Figure 8d-f shows that the WNZ contains a range of features (Su et al [29]). Greater peak WNZ temperatures in the case of asbestos backing plate result in greater recovery and lower dislocation densities.…”

Enhancing mechanical properties of friction stir welded 2219Al-T6 joints at high welding speed through water cooling and post-welding artificial ageing

“…For FSW precipitation-hardened (2xxx, 6xxx, and 7xxx) aluminium alloys, it has been generally reported that the heat-affected zone (HAZ) is the low hardness zone (LHZ) due to significant dissolution/coarsening of the precipitates during the FSW thermal cycle [7][8][9][10][11][12][13]. For the 2219Al-T6 alloy, although the FSW joints have been reported to have better joint efficiency compared to the fusion welded joints, the gap between the strength values of the base metal (BM) and the FSW joints is still large (N 25%) due to the softening problem of the HAZ [7][8][9].…”

The effect of pin profiles on the microstructure and mechanical properties of underwater friction stir welded AA2519-T87 aluminium alloy

“…Zhang et al reported that the performance of UWFSW joints of AA2219 Al alloy was enhanced by narrowing the width of the HAZ. Moreover, the controlling of thermal cycles using water cooling improves the hardness from 78 to 98 HV in the LHDR (Zhang et al 2012). Liu et al made an investigation on the tensile properties of FSW and UWFSW of AA2219 Al alloy.…”