Fatigue behavior prediction of metal alloys based on a unified multiscale crack growth model

• Published in: Engineering fracture mechanics Vol. 235; p. 107132
• Main Authors: Tang, Keke, Du, Zhaojun, Wu, Baijian, Hou, Jixin
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 01.08.2020; Elsevier BV
• Subjects: Crack propagation; Crystal defects; Fatigue failure; Fatigue life; Fatigue life prediction; Grain size; Growth models; Life prediction; Metal alloys; Metal fatigue; Nickel alloys; Nickel base alloys; Short crack; Short cracks; Superalloys; Titanium alloys; Titanium base alloys; Unified multiscale crack growth model; Grain size; Short crack; Fatigue life prediction; Unified multiscale crack growth model; Metal alloys
• ISSN: 0013-7944; 1873-7315
• DOI: 10.1016/j.engfracmech.2020.107132

•A unified multiscale fatigue crack growth model is proposed for life prediction of metal alloys.•Crack driving force and non-propagation regime are interpreted through the Chapetti’s expression of threshold.•The proposed model is validated through a variety of experimental data and life prediction results tend to be consistent and conservative.•The multiscale model is able to interpret the scatter of data points through grain size variation. The aim of this paper is to establish a multiscale crack growth model that considers the segmented stages of microstructurally short crack (MSC), physically short crack (PSC) as well as long crack (LC). The proposed multiscale model is based on the crack driving force defined by Chapetti, which briefly accounts for the crack propagation behaviors at MSC stage. Experiments on Ti-6Al-4V titanium alloy are performed. Test data from the experiments and published literatures are essentially in agreement with the predicted curves generated from the multiscale model. Application of the proposed model is further demonstrated by the fatigue life prediction of GH4169 Nickel-based alloy with different initial defects. It is found that, compared with previous models, life prediction results from the multiscale model tend to be more consistent with the test data collected from published literatures, and appear to be relatively conservative. Preliminary analysis indicates that the grain size has significant influence on the fatigue life of Nickel-based alloy that decreases substantially over the grain size increase. The scatter in fatigue lives can be reflected by the variation of grain size. These findings offer certain understanding of crack propagation and fatigue life evaluation to scientific and engineering communities.