Relation between crack growth behaviour and crack front morphology under hold-time conditions in DA Inconel 718. (March 2017)

• Record Type: Journal Article
• Authors: Fessler, E.; Andrieu, E.; Bonnand, V.; Chiaruttini, V.; Pierret, S.
• Is Part Of: International journal of fatigue. Volume 96(2017)
• Page Start: 17
• Page End: 27
• Publication Date: 2017-03
• Subjects: Crack growth -- Hold-time -- Crack front shape -- Potential drop -- DA Inconel 718; Materials -- Fatigue -- Periodicals; Materials -- Fatigue; Periodicals; 620.1122
• DOI: 10.1016/j.ijfatigue.2016.11.015
• Languages: English
• ISSNs: 0142-1123

Abstract

Highlights: Crack growth behaviour of DA Inconel 718 was related to crack front morphology. High CGRs are related to complex crack front morphology. The effect crack morphology on the DCPD technique is numerically investigated. High CGRs are related to the evolution of crack front morphology. Abstract: The crack growth behaviour of Direct Aged Inconel 718 was studied at 550 °C. Experiments were carried out under pure fatigue cycles, hold-time cycles of different durations and a mix of both. Hold-time cycles were systematically associated with complex crack front morphologies. A new numerical approach was developed to assess the effect of crack front morphology on the direct current potential drop technique, mechanical fields at the crack tip and ultimately, measured crack growth rates. Using this approach, a clear relation was established between crack front morphology and its evolution, and the crack growth behaviour under hold-time conditions. Complex crack front morphologies are demonstrated to be responsible for increased crack growth rates. From this, a crack growth mechanism under hold-time conditions is proposed. Finally, the numerical framework here presented is to be considered as a new, easily reproducible, way to properly analyse experimental data when dealing with complex loading cycles and complex crack front morphologies.