Near-threshold fatigue resistance of micrometer-grained steel welds: mechanisms and modeling

IF 7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue Pub Date : 2026-06-01 Epub Date: 2026-01-16 DOI:10.1016/j.ijfatigue.2026.109494

Quan-Heng Yao, Rong Chen, Wen-Qing Lu, Xu-Yang Mo, Ming-Liang Zhu, Fu-Zhen Xuan

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Abstract

Materials with coarse grains are believed to have higher fatigue threshold with respect to damage tolerance design, in such a context, the mechanisms for fine grains governing fatigue crack propagation are not clear. In this study, the near-threshold fatigue crack propagation behavior of L907A steel welded joints with micrometer-size grains (∼2.5 μm) was investigated, and the associated damage mechanisms near crack-tip were analyzed. It was found that fine grains tended to have lower transition rate down to the near-threshold regime due to the interaction of cyclic plasticity and microstructures, which promoted the formation of nanovoids, nanograins, and amorphization near crack-tip. A modified Zhu-Xuan model was established by taking into account the local microhardness and stress ratios. These findings underscore the importance of grain size engineering in enhancing fatigue resistance and show promise for streamlining the fatigue threshold testing process, thereby reducing associated time and costs.

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微米晶粒钢焊缝的近阈值抗疲劳：机理与建模

粗晶材料在损伤容限设计中被认为具有更高的疲劳阈值，在这种情况下，细晶控制疲劳裂纹扩展的机制尚不清楚。本文研究了L907A钢微米级（~ 2.5 μm）晶粒焊接接头的近阈值疲劳裂纹扩展行为，并分析了裂纹尖端附近的损伤机制。结果表明，由于循环塑性和微观组织的相互作用，细晶向近阈值区转变的速率较低，促进了裂纹尖端附近纳米孔洞、纳米晶粒的形成和非晶化。考虑了局部显微硬度和应力比，建立了修正的Zhu-Xuan模型。这些发现强调了晶粒尺寸工程在提高抗疲劳性能方面的重要性，并显示出简化疲劳阈值测试过程的希望，从而减少了相关的时间和成本。

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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.