Corrosion Fatigue Of Al-alloy Aa7020 In Different Surface Treatment States

Author:  K. Timmermann, W. Zinn, B. Scholtes
Source:  Conf Proc: ICSP-10 Tokyo, Japan 2008
Doc ID:  2008095
Year of Publication:  2008
Abstract:  
ABSTRACT The consequences of near surface materials properties due to distinct manufacturing operations on damage evolution during corrosion fatigue of the Al-base alloy AA7020 (German grade AlZn4.5Mg1) were systematically investigated. Specimens with distinct shot peening treatments were investigated in comparison with turned or polished states. Surface topography as well as near surface work hardening states and residual stress distributions were taken into account. Bending fatigue tests under salt spray test conditions were carried out and crack formation as well as crack propagation were studied in comparison with fatigue tests in laboratory air. It could be shown, that mechanical surface treatments, which have beneficial effects in dry air are also advantageous under corrosion fatigue conditions. Characteristic results are presented and discussed taking the stability of near surface materials properties during fatigue into account. KEY WORDS Corrosion fatigue, aluminium alloys, shot peening, salt spray test, residual stress