Effect of Pulse Duration on Corrosion and Impression Creep Properties of AA5083‐H111 Al–Mg Alloy Weldments Processed by P‐GTAW. Issue 6 (1st March 2018)

• Record Type: Journal Article
• Authors: Umar­, Mustafa; Sathiya, Paulraj
• Other Names: Zschech Ehrenfried guestEditor.
• Is Part Of: Advanced engineering materials. Volume 20:Issue 6(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-03-01
• Subjects: Aluminum alloy -- Corrosion -- Impression creep -- Intermetallics -- Pulse duration; Materials -- Periodicals; 620.11
• DOI: 10.1002/adem.201701147
• Languages: English
• ISSNs: 1438-1656

Abstract

Abstract : In this work, the corrosion and impression creep properties of weldments are determined using potentiodynamic polarization test and impression creep test. It is evident that the shorter pulse duration results in comparatively finer grains and reduces the loss of magnesium in fusion zone, which facilitates an increase in precipitation of anodic β ‐phase (Al3 Mg2 ) and Mg2 Si particles in the grain boundaries. It leads to the formation of pits by dissolving Mg atoms and propagate along the interdendritic region and finally corrode the surface thoroughly. On contrary, the increase in pulse duration results in uniform distribution of iron‐rich Al6 (Fe, Mn) intermetallics as well as Fe and Mn particles in the interdendritic region which induce localized cathodic reaction and these localized cathodes assisted in achieving noble corrosion resistance by increasing the width of passive region. Also, an increase in creep resistance is attained with an increase in activation energy at a temperature of 573 K owing to the uniform dispersion of iron‐rich Al6 (Fe, Mn) intermetallics in the grain boundaries of weldments processed with longer pulse duration. Hence, it is inferred from this research that the rise in pulse duration improves the corrosion and creep resistance of weldments by altering the morphology and surface distribution of intermetallics. Abstract : Role of intermetallics: In P‐GTAW, the change in pulse duration affects the morphology of intermetallics. Longer pulse duration produces Al6 (Fe, Mn) intermetallics at grain boundaries and gives rise to the passivity breakdown potential. The Al6 (Fe, Mn) promotes cathodic reaction during corrosion which results in deeper pits and crevices at the intermetallic boundaries.