Open AccessRole of Crack-Tip Residual Stresses in Stress Corrosion Behavior of Pre-stressing AA7020
Author(s) -
Ashish Thakur
Publication year - 2019
Publication title -
international journal of current engineering and technology
Language(s) - English
Resource type - Journals
eISSN - 2347-5161
pISSN - 2277-4106
DOI - 10.14741/ijcet/v.9.3.7
Subject(s) - materials science , residual stress , cracking , stress corrosion cracking , crack closure , metallurgy , corrosion , composite material , corrosion fatigue , alloy , aluminium , fracture (geology) , environmental stress fracture , compressive strength , stress (linguistics) , stress concentration , dissolution , fracture mechanics , linguistics , philosophy , chemistry
This paper analyzes stress corrosion cracking (SCC) of pre-cracked samples in the presence of compressive residualstresses generated in the vicinity of the crack tip during fatigue pre-cracking. Research focuses on the role of cracktip residual stresses of compressive nature, generated by fatigue loading, in stress corrosion cracking of pre-crackedsamples of medium high strength aluminum alloy 7020 subjected to localized anodic dissolution and hydrogenassisted cracking. Fatigue pre-cracking load on the samples generates compressive residual stresses in the vicinity ofthe crack tip which improve the stress corrosion behavior of the aluminum alloy by delaying either the metaldissolution or the hydrogen entry, thus increasing the fracture load in an aggressive environment. The rice model ofthe residual stress distribution in the vicinity of a crack tip may be usedto explain these retardation effects byestimating the stress level and plastic zone size. Microscopically, compressive residual stress produce a transitiontopography between the fatigue pre-crack and the cleavage-like (unstable) fracture mode.