Corrosion Performance of Friction Stir Linear Lap Welded AM60B Joints

Abstract

A corrosion investigation of friction stir linear lap welded AM60B joints used to fabricate an Mg alloy-intensive automotive front end sub-assembly was performed. The stir zone exhibited a slightly refined grain size and significant break-up and redistribution of the divorced Mg 17 Al 12 (-phase) relative to the base material. Exposures in NaCl (aq) environments revealed that the stir zone was more susceptible to localized corrosion than the base material. Scanning vibrating electrode technique (SVET) measurements revealed differential galvanic activity across the joint. Anodic activity was confined to the stir zone surface and involved initiation and lateral propagation of localized filaments. Cathodic activity was initially confined to the base material surface, but was rapidly modified to include the cathodically-activated corrosion products in the filament wake. Site-specific surface analyses revealed that the corrosion observed across the welded joint was likely linked to variations in Al distribution across the surface film/metal interface.

Effect of unequal levels of deformation and fragmentation on the electrochemical response of friction stir welded AA2024-T3 alloy

“…The development of techniques for in situ characterization of localized electrochemical activities has helped to add more insight into the understanding of SLC initiation and propagation. A few studies have successfully employed techniques such as scanning electrochemical microscopy (SECM) [16], scanning vibrating electrode technique (SVET) [17][18][19] and localized electrochemical impedance spectroscopy (LEIS) [20] to reveal the corrosion modes and the regions that are most susceptible to corrosion in friction stir weldments. Thus, in this work, localized electrochemical techniques including the SVET and LEIS have been employed to reveal the difference between the corrosion behaviour of the advancing and retreating sides of the friction stir weldment of the AA2024-T3 alloy.…”

Effect of TIG Welding and Rare Earth Elements Alloying on Corrosion Resistance of Magnesium Alloys

“…The common belief in the literature is that welding causes the refinement of the grains of the alloy with a decrease in the grain size and homogenization of the alloy composition. 11,34,56 The refinement of the grain size in the case of all investigated alloys (see Fig. 4) was observed, however, the interpretation of the results of the electrochemical measurements (Figs.…”

“…The corrosion resistance of FSW welded AM60B alloy was investigated in Ref. 34 and it was found that SZ showed higher susceptibility to localized corrosion than BM. The authors ascribed the differences in the susceptibility to corrosion to the differences in the β-phase morphology between BM an SZ.…”

On the mechanical, microstructural, and corrosion properties of pulsed gas tungsten arc and friction stir welded RZ5 rare earth grade magnesium alloy

“…Eivani et al [46] reported that the second phase particle breakup and redispersion resulted in a stronger protective layer and enhanced corrosion resistance of multipass FS-treated WE43 magnesium alloy. Kish et al [47] reported that the resident potentials are imperative in determining overall anodic and cathodic regions and the corrosion propagation (i.e., spreading of corrosion) depends on the breakdown voltage. In FSW joint, the resident potential balanced the cathodic and anodic activity by producing ultrafine grains.…”