The Role of Hydrogen in the Stress Corrosion Failure of High Strength Al-Zn-Mg Alloys.
Annual rept. Sep 80-Oct 82,
IMPERIAL COLL OF SCIENCE AND TECHNOLOGY LONDON (ENGLAND)
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Three alloys, Al 6 Zn 3 Mg. Al 6 Zn 3 Mg 1.7 Cu and Al 6 Zn 3 Mg 0.14 Cr. were pre-exposed in the solution treated condition to water vapour at 115C. Dry control tests were also performed. Both sets of samples were tested in tension using a slow strain rate of 11,000,000S and the results were compared with previously obtained data using a strain rate of 11000S. All the samples exposed to steam showed evidence of hydrogen embrittlement, the effects being more severe at the slow strain rate. Evidence was also obtained for hydrogen embrittlement via reaction of the metal with the laboratory air during slow strain rate testing in all cases except for the copper containing alloy. Both intergranular and transgranular brittle fracture can be produced as a result of hydrogen absorption into the metal tolerance to hydrogen is related to the ability of the microstructure to trap hydrogen in the form of gas bubbles.
- Properties of Metals and Alloys