Model for predicting fatigue life and limit of steels based on micromechanics of small crack growth

Publication date: 5 February 2018
Source:Materials & Design, Volume 139
Author(s): Kazuki Shibanuma, Koya Ueda, Hiroaki Ito, Yoshiki Nemoto, Masao Kinefuchi, Katsuyuki Suzuki, Manabu Enoki
A model for predicting the fatigue life and limit of steels with banded ferrite-pearlite microstructures is proposed based on the micromechanics of small crack behavior. The model was simplified to a two-step 2D problem: (i) determination of crack initiation site on the surface plane; (ii) fatigue life evaluation by simulating crack growth on the inside plane. A multiscale model synthesis approach was used to integrate three elemental models of (i) macroscopic finite element analysis, (ii) geometries and spatial distributions of ferrite grains and pearlite colonies, and (iii) crack initiation and growth. The required input data consisted of only (i) microstructural information, (ii) monotonic tensile properties, and (iii) test conditions. Model validation was performed by comparing the experimental results using steels with various volume fractions of pearlite phases and grain sizes. The predicted fatigue lives and limits were in good agreement with the experimental data for all the steels. In addition, the model could accurately simulate the crack growth behavior observed by optical microscopy. The framework of the proposed model may serve as a basis for predicting the fatigue lives of metallic structural materials.

Graphical abstract

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