Precipitation behavior and corrosion properties of friction stir welded AA5083 Al Mg alloy after sensitization

Precipitation Behavior and Corrosion Properties of Stirred Zone in FSWed AA5083 Al-Mg Alloy after Sensitization

“…Figure 10 shows the SSRT curves of the 175 • C/100 h sensitized SZs at an initial strain rate of 1 × 10 −5 s −1 . The excellent SCC immunity in the as-welded SZ was quantitatively confirmed by the stress vs. strain curves and the fracture morphologies in our previous work [29]; thus, only the SSRT results of sensitized SZs are exhibited herein. The yield stress (YS), ultimate tensile strength (UTS), elongation, and SCC susceptibility indices (I SSRT ) are summarized in Table 2.…”

“…The fragmentations of the primitive intermetallic particles were apparently observed in the SZ, induced by the severe rotation action of the stir pin during the FSW process. The rodshaped pre-existing particles are hypothetically assumed to be Al6(Mn-Fe-Cr-Si) or Mg2Si, as proven by our previous work [29]. As expected, a large number of dislocation entanglements was present in the matrix or intersecting with the GBs or the pre-existing particles.…”

“…These unique corrosion morphologies were triggered by the anodic dissolution of the GBs decorated by the relatively continuous Mg-rich phase with high electro-chemical activity. Our previous studies provided evidence that the grain morphology (e.g., shape and size) strongly affects the IGC tendency [29]. Although NAMLT values indicate that the samples removed from the middle and bottom of the SZ exhibited weaker IGC resistance than those removed from the top, little difference in the corrosion morphology could be detected.…”

“…Excellent mechanical properties can be obtained, and the solidification defects, such as pores and hot cracks, observed in the traditional fusion welding processes can be effectively avoided via dynamic recrystallization [25][26][27][28]. In recent years, studies have been conducted on the Mg-rich phase precipitation behavior of FSWed Al-Mg alloys [29][30][31], and FSW was adopted as a reverse heat treatment aiming to eliminate sensitization [32]. Our previous work demonstrated that the thermal-mechanical affected zone (TMAZ) and the stirred zone (SZ) exhibited more severe IGC/SCC susceptibility compared with the base metal [29].…”

“…In recent years, studies have been conducted on the Mg-rich phase precipitation behavior of FSWed Al-Mg alloys [29][30][31], and FSW was adopted as a reverse heat treatment aiming to eliminate sensitization [32]. Our previous work demonstrated that the thermal-mechanical affected zone (TMAZ) and the stirred zone (SZ) exhibited more severe IGC/SCC susceptibility compared with the base metal [29]. The large corrosion tendency exhibited in the SZ after sensitization was also confirmed by Qiu's work via potentiodynamic polarization curves and NAMLT tests [31].…”