Effect of inherent defects on initiation of stress-corrosion cracks in weldable Al–Zn–Mg alloys

Abstract

Abstract The presence of inherent defects in three commercial weldable Al-Zn-Mg alloys renders slow-strain-rate testing of smooth tensile specimens unreliable for assessing susceptibility to stress-corrosion failure, unless flawed specimens are recognizable and occur sufficiently infrequently for them to be rejected. The flaws present in the alloys investigated consisted of thin sheets of magnesium oxide parallel to the rolling plane and therefore perpendicular to the direction of maximum susceptibility to stress-corrosion failure. Because the flaws have much less effect on the initiation of stress-corrosion cracks in precracked specimens, the stress-intensity factors determined for such initiation in various environments do provide a reliable assessment of susceptibility.