THE EFFECT OF MICROSTRUCTURE ON THE STRESS-CORROSION SUSCEPTIBILITY OF AN A1-Zn-Mg ALLOY
CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF METALLURGICAL ENGINEERING AND MATERIALS SCIENCE
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The effect of microstructure on the susceptibility of a high purity Al-6.8 Zn-2.3 Mg alloy to stress-corrosion cracking in an aqueous salt solution 3.5 wt NaCl was studied. The results of testing a series of specimens having controlled microstructures and the same yield strength of 40, 000 psi indicate that the susceptibility to stress-corrosion is controlled by the type, size, and spacing of the matrix precipitate through the effect of these precipitates on the deformation process. Although the width of the precipitate free zone appears to have no effect on susceptibility, the grain boundary precipitate seems to influence susceptibility in certain cases. Supporting evidence for these observations was obtained by light and electron microscopic examinations of deformed specimens and by fractographic studies. A model is proposed which explains many experimental observations.
- Properties of Metals and Alloys