Effect of tensile pre-strain on low-cycle fatigue behaviour of 7050-T6 aluminium alloy. (August 2020)

• Record Type: Journal Article
• Authors: Branco, R.; Costa, J.D.; Borrego, L.P.; Wu, S.C.; Long, X.Y.; Antunes, F.V.
• Is Part Of: Engineering failure analysis. Volume 114(2020)
• Publication Date: 2020-08
• Subjects: Pre-strain -- Low-cycle fatigue -- Cyclic plastic behaviour -- Strain energy density -- 7050-T6 aluminium alloy; System failures (Engineering) -- Periodicals; Fracture mechanics -- Periodicals; Reliability (Engineering) -- Periodicals; Pannes -- Périodiques; Rupture, Mécanique de la -- Périodiques; Fiabilité -- Périodiques; Fracture mechanics; Reliability (Engineering); System failures (Engineering); Periodicals; Electronic journals; 620.112
• DOI: 10.1016/j.engfailanal.2020.104592
• Languages: English
• ISSNs: 1350-6307

Abstract

Highlights: Effect of tensile pre-strain on LCF 7050-T6 aluminium alloy is studied. Tensile pre-strain caused a mixed softening/hardening behaviour. Full relaxation of mean stress occurred only at higher strain amplitudes. Fatigue lifetime decreased with increasing tensile pre-strain. Abstract: The present study addresses the effect of tensile pre-strain histories on cyclic plastic deformation behaviour of 7050-T6 aluminium alloy. Low-cycle fatigue tests are conducted under fully-reversed conditions, with 8% tensile pre-strain, 4% tensile pre-strain, and 0% tensile pre-strain, at different strain amplitudes. After fatigue testing, fracture surfaces are examined by scanning electron microscopy and transmission electron microscopy to identify the main failure micro-mechanisms associated with the levels of pre-strain and strain amplitude. Microstructure is analysed by X-ray diffraction, transmission electron microscopy, and optical microscopy. The main findings suggest that tensile pre-strain histories are conducive to a reduction in fatigue life. This reduction increases with higher strain amplitudes.