Pitting-induced hydrogen embrittlement of magnesium–aluminium alloy

Abstract

a b s t r a c tIn this study, the pitting corrosion susceptibility and its role on the hydrogen embrittlement behaviour of AZ80 magnesium alloy were studied using slow strain rate testing (SSRT), electrochemical technique and immersion test method. The electrochemical and immersion tests in chloride-containing solution revealed severe pitting corrosion in the alloy. The SSRT results of the alloy under continuously-exposed conditions in chloride-containing solution and in distilled water showed that the mechanical properties of the alloy deteriorated considerably in both the solutions. Pre-exposure of the alloy in distilled water did not show any considerable change in the mechanical properties of the alloy, however in chloride-containing solution a significant loss in the mechanical properties was noticed. Cleavage facets were observed in the vicinity of the localized attacked region of the alloy pre-exposed in chloride-containing solution. Interestingly, desiccating the pre-exposed (in chloride-containing solution) samples reduced the loss in the mechanical properties, which could be attributed to reversible hydrogen. Thus, the study suggests that pitting corrosion facilitates hydrogen entry into the alloy and causes hydrogen embrittlement.

The Effect of Laser Shock Peening on the Corrosion Behavior of Biocompatible Magnesium Alloy ZK60

“…Other, heavy metals in ZK60 can also promote pitting corrosion [25]. When pitting occurs, hydrogen tends to gather in the defected part of the material (corrosive pitting pits) to weaken the atomic bonding of the material matrix and causes hydrogen embrittlement [26]. Meanwhile, stress concentration is natural to occur in corrosive pitting pits, so the crack initiation occurs through corrosive pitting.…”

Stress Corrosion Cracking Resistance of Cold-Sprayed Al 6061 Deposits Using a Newly Developed Test Fixture

“…Additionally, precipitates can cause areas of localized corrosion because of differences in corrosion potential as compared with surrounding areas, resulting in hydrogen evolution, promoting SCC [7][8][9][10]17,[48][49]. The build-up of hydrogen can eventually embrittle the material and cause cracking [11][12][13]. Since the cold spray deposit was in the as-deposited condition, while the wrought Al 6061 in the T6, EDS was conducted to evaluate the elemental differences in fracture surfaces between the two materials.…”

“…As a low-temperature process, it operates below the melting point of metals and results in very low porosity deposits without the need for combustible gasses. Additional motivation to use this process is the low oxide content, which can improve corrosion resistance, mechanical properties, and wear resistance by eliminating sites for localized corrosion and premature failure.There has been a great deal of research into corrosion mechanisms in metallic materials over the past century [5][6][7][8][9][10][11][12][13][14][15][16][17]. Atmospheric or environmentally assisted corrosion is one of the least understood areas of corrosion.…”

Transformation between localized and general corrosion behavior of die‐cast AZ91D magnesium alloy in 3.5 wt% NaCl aqueous solutions

“…In addition, Mg alloy has a highly negative electrochemical standard potential −2.37 V compared to the standard hydrogen electrode and enhanced susceptibility to corrosion in active media . Currently, Mg alloys in the automotive industry are simply being considered for uses in mild service environments . Significant improvement in the corrosion resistance of Mg alloys is a challenging task.…”