Please click Additional Files below to see the full abstrac

Bahsoun, Hadi

Benoit, Guillaume

Billaudeau, Thomas

de Araujo, Manuel

Hénaff, Gilbert

Rousset, Jérôme

Saanouni, Sarah

Villechaise, Patrick

English

Engineering Conferences International

ON THE POSSIBLE ROLE OF HYDROGEN IN THE FORMATION OF FATIGUE STRIATION IN A MOIST ATMOSPHERE   Gilbert Hénaff, Institut Pprime, UPR3346 CNRS ENSMA Université de Poitiers, Futuroscope-Chasseneuil, France Gilbert.henaff@isae-ensma.fr Sarah Saanouni, Institut Pprime, UPR3346 CNRS ENSMA Université de Poitiers, Futuroscope-Chasseneuil, France Guillaume Benoit, Institut Pprime, UPR3346 CNRS ENSMA Université de Poitiers, Futuroscope-Chasseneuil, France Thomas Billaudeau, Airframe Research & Technology, Airbus Operations SAS, Saint Martin du Touch, France Manuel de Araujo, Airframe Research & Technology, Airbus Operations SAS, Saint Martin du Touch, France Jérôme Rousset, Airframe Research & Technology, Airbus Operations SAS, Saint Martin du Touch, France Hadi Bahsoun, Institut Pprime, UPR3346 CNRS ENSMA Université de Poitiers, Futuroscope-Chasseneuil, France Patrick Villechaise, Institut Pprime, UPR3346 CNRS ENSMA Université de Poitiers, Futuroscope-Chasseneuil, France   In this study, the effect of the exposure to moist air on the fatigue crack growth in 7175 T7351 aluminium alloy is investigated. A special attention is paid to the crack-tip deformation mechanisms, controlling the fatigue crack growth rate as well as to the fatigue striation markings on the fracture surfaces. Two extreme fatigue crack growth conditions in terms of exposure rate to water vapor have been considered with this aim, namely a moist air and at low loading frequency, corresponding to a high exposure rate, and a low exposure rate condition obtained in an inert atmosphere. Observations of the corresponding fracture surfaces along with subsurface deformation structures in FIB foils milled from selected  areas at a selected ΔK value are presented. It is noticed that a high exposure rate induces the development at the crack-tip of a 800 nm-thick surface layer. In addition, EBSD analysis reveal that this layer is actually divided into subdomains characterized with a pronounced and highly localized lattice rotation. In contrast, under very low exposure rate, a significantly lower lattice rotation associated with a smoother gradient is observed. This suggests that the formation of subdomains at high exposure rate is actually induced by some environmental effect. More precisely, a scenario of striation formation is proposed, where hydrogen, highly concentrated in the subsurface layer due to its low diffusivity, would favor intense localization of crack-tip deformation leading to the observed high rotation of the lattice. Furthermore, a one-to-one correspondence between the fatigue striation spacing on the hand, and the distance separating two successive subdomains exhibiting the highest lattice disorientation on the other hand, has been clearly established 

On the possible role of hydrogen in the formation of fatigue striation in a moist atmosphere

https://dc.engconfintl.org/cgi/viewcontent.cgi?filename=0&article=1026&context=hydrogen&type=additional

On the possible role of hydrogen in the formation of fatigue striation in a moist atmosphere

Abstract

Similar works

Full text

Available Versions

Engineering Conferences International