Residual stress relaxation of railway gradient S38C steel during fatigue crack growth by neutron imaging and diffraction

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue Pub Date : 2025-01-17 DOI:10.1016/j.ijfatigue.2025.108826

Feifei Hu, Tianyu Qin, Yuhua Su, Lunhua He, Ni Ao, Joseph Don Parker, Takenao Shinohara, Shengchuan Wu

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引用次数: 0

Abstract

The S38C steel axles show excellent fatigue resistance due to large-depth compressive residual stress (CRS) along the axial direction. However, residual stress (RS) relaxation may occur in case of a fatigue crack, which results in a reduced damage tolerance and a shortened service lifetime. Destructive methods cannot retain the residual stress and associated retardation effect of cracks. To tackle this concern, time-of-flight (TOF) methods of Bragg-edge transmission (BET) imaging and neutron diffraction (ND) were introduced to quasi-in situ investigate the residual stress relaxation during fatigue crack propagation by single-edge notch bending samples. The BET imaging results indicate that lattice parameters change as the crack develops, which then leads to a decrease of residual strain ε110. It was clearly found that the maximum ε110 was released by ∼ 31.4 % if a crack propagated to 10.0 mm. In addition, it was observed from ND results that all three RS components decrease with the crack growth. By contrast, the CRS in the axle surface was almost fully released when the crack propagated to the matrix material zone (from −566 to 41 MPa). Furthermore, RS relaxation was validated by the extended finite element method, and the effect of stress relaxation on stress field at the crack tip was also evaluated meticulously. These new insights confirm stress relaxation in railway S38C axles during crack propagation, which must be considered while carrying out the structural integrity assessment.

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来源期刊

International Journal of Fatigue 工程技术-材料科学：综合

CiteScore

10.70

自引率

21.70%

发文量

619

审稿时长

58 days

期刊介绍： Typical subjects discussed in International Journal of Fatigue address: Novel fatigue testing and characterization methods (new kinds of fatigue tests, critical evaluation of existing methods, in situ measurement of fatigue degradation, non-contact field measurements) Multiaxial fatigue and complex loading effects of materials and structures, exploring state-of-the-art concepts in degradation under cyclic loading Fatigue in the very high cycle regime, including failure mode transitions from surface to subsurface, effects of surface treatment, processing, and loading conditions Modeling (including degradation processes and related driving forces, multiscale/multi-resolution methods, computational hierarchical and concurrent methods for coupled component and material responses, novel methods for notch root analysis, fracture mechanics, damage mechanics, crack growth kinetics, life prediction and durability, and prediction of stochastic fatigue behavior reflecting microstructure and service conditions) Models for early stages of fatigue crack formation and growth that explicitly consider microstructure and relevant materials science aspects Understanding the influence or manufacturing and processing route on fatigue degradation, and embedding this understanding in more predictive schemes for mitigation and design against fatigue Prognosis and damage state awareness (including sensors, monitoring, methodology, interactive control, accelerated methods, data interpretation) Applications of technologies associated with fatigue and their implications for structural integrity and reliability. This includes issues related to design, operation and maintenance, i.e., life cycle engineering Smart materials and structures that can sense and mitigate fatigue degradation Fatigue of devices and structures at small scales, including effects of process route and surfaces/interfaces.