Initial Crack Extension in Two Intermediate-Strength Aluminum Alloys

Abstract

Three-point bend tests were conducted to examine the geometry dependence of JIc in two intermediate-strength aluminum alloys, 2024-T351 and 7005-T6351. The amounts of crack growth at selected points on the load-versus-deflection curves were delineated using a heat tinting technique. Resistance curves of J-versus-crack extension were constructed to facilitate determination of JIc at incipient crack movement. The through-thickness variation in fracture toughness of a 7.6-cm-thick plate of 7005 aluminum was determined and correlated with fractographic and metallographic observations. The current JIc measurements from subsized specimens of 7005 aluminum are compared with previous KIc characterizations using linear-elastic, full-thickness specimens.