Effects of sensitization on environmentally assisted cracking of AA5083-H128 Al-Mg alloy

The influence of sensitization on the precipitation behaviour and environmentally assisted cracking (EAC) of AA5083 alloy with the -H128 temper have been investigated. 80 degrees C/500 h and 80 degrees C/1000 h sensitized specimens exhibit discontinuous Mg-rich precipitates along the grain boundaries, whereas almost continuous beta phase is present along the grain boundaries in the 175 degrees C/100 h sensitized material. EAC susceptibility increases with increasing exposure time and elevated temperature. The relationship between nitric acid mass loss test (NAMLT) values and mechanical test results indicates that specimens with a NAMLT value greater than 25 mg/cm(2) exhibit severe EAC. The test environment affects the degree of EAC due to the combined effects of anodic dissolution at the crack tip, hydrogen evolution, and hydrogen embrittlement. AA5083-H128 exhibits lower EAC susceptibility than AA5083-H131, likely due to its lower yield strength. High yield strength can produce more Mg-rich precipitates after sensitization, increase the constraint of the crack tip material and accelerate the diffusion rate of H atoms in the process zone of the crack tip. (c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The influence of sensitization on the precipitation behavior and environmentally assisted cracking (EAC) of AA5083 alloy with the -H128 temper is investigated. The EAC susceptibility increases with increasing exposure time and elevated temperature. The relationship between nitric acid mass loss test (NAMLT) values and mechanical test results indicates that specimens with a NAMLT value greater than 25 mg/cm(2) exhibit severe EAC.