What is it about?
In this manuscript, we investigate the influence of hydrogen on the environmentally assisted cracking of the high-strength magnesium alloy AZ31B.
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Why is it important?
Based on the reversibility of the pre-exposure embrittlement effect, we were able to demonstrate that the AZ31B alloy was, indeed, susceptible to internal hydrogen embrittlement. The width of the annular brittle region observed in post-exposure fractography, doubled with a fourfold increase in pre-exposure time, suggesting that hydrogen diffusion controlled pre-exposure embrittlement. Similarly, pre-corroded tensile samples of AZ31B Mg alloy showed a decrease in ductility and UTS that was a function of the pre-exposure time. In all cases, the loss of ductility, which was not influenced by chloride concentration, was partly recovered by exposure to dry air. Moreover, results conclusively showed that anodic processes were not rate-controlling. It is plausible to assume that other high-strength magnesium alloys could exhibit a similar behavior.
Perspectives
In this manuscript, we were able to conclusively quantify the effect of hydrogen on environmentally assisted cracking of high strength magnesium alloys. The extensive test matrix allowed us to demonstrate that anodic processes were not rate controlling and that alloy AZ31B was, indeed, affected by internal hydrogen embrittlement.
Dr Mariano Iannuzzi
Norwegian University of Science and Technology
Read the Original
This page is a summary of: Pre-Exposure Embrittlement and Stress Corrosion Cracking of Magnesium Alloy AZ31B in Chloride Solutions, CORROSION, July 2014, NACE International,
DOI: 10.5006/1172.
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