Evaluation of toughness in 7075 alloy by R curve method

Abstract

Direct current electrical potential method, instrumented Charpy impact test, key curve method, compliance changing rate method, fractography or NRL type dynamic tear test are carried out for the evaluation of static and dynamic crack initiation resistance toughness (JId, JIC) and crack propagation resistance toughness (JRcurve, Tmat). The static JRcurve and Tmatshows plate thickness dependency; the crack propagation resistance toughness is larger as plate thickness is smaller. The dynamic Tmat shows strain rate dependency. Each method is proved to be sufficiently effective for the toughness evaluation of the aircraft material; 7075 (Al-Zn-Mg-Cu type) alloy. © 1986, The Japan Institute of Light Metals. All rights reserved.