Probabilistic evaluation on fatigue small cracking characteristics of light metallic alloys under in-situ SEM fatigue tests using the weakest link theory

IF 6.8 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue Pub Date : 2026-07-01 Epub Date: 2026-02-08 DOI:10.1016/j.ijfatigue.2026.109557

Yang Xin-Yi , Zhu Li-Na , Xu Zhong-Wei , Wang Xi-Shu

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引用次数: 0

Abstract

In this work, the key mechanics parameters such as ΔK_th and critical damage tolerance size (DTS: a_0H) were quantitatively estimated with a 95% probability through the weakest-link theory (WLT) and in-situ scanning electron microscopy (SEM) fatigue small crack (FSC) propagation tests for the cast AM60 magnesium, SLM-AlSi10Mg and SLM-Ti6Al4V alloys. A new probability evaluation model about the dispersion range in FSC growth rate curves of these materials was developed. The dispersions of da/dN indicated that the mapping correlation to ΔK_th of SLM-Ti6Al4V alloy exhibits higher accuracy than that of the other two alloys. And the DTS of three alloys were also quantitatively obtained by comparison with fatigue cracking source and microstructure characteristic size. The probability of high cycle fatigue failure is reduced to only 5% when the DTS is respectively controlled within the estimated size such as 37.1 μm for cast AM60, 89.0 μm for SLM-AlSi10Mg and 75.3 μm for SLM-Ti6Al4V. The relative error between the 95% probability estimation values and average defect size is 25.8%, 8.4% and 4.6%, respectively. The effectiveness and reasonableness of these estimation values were validated by the experimental and literature data.

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基于最薄弱环节理论的轻金属合金原位SEM疲劳试验疲劳小裂纹特性概率评价

通过最薄弱环节理论（WLT）和原位扫描电镜（SEM）疲劳小裂纹（FSC）扩展试验，以95%的概率对铸态AM60镁合金、SLM-AlSi10Mg和SLM-Ti6Al4V合金的关键力学参数ΔKth和临界损伤容限尺寸（DTS: a0H）进行了定量估计。提出了一种新的关于这些材料FSC生长速率曲线色散范围的概率评价模型。da/dN的分散表明，SLM-Ti6Al4V合金与ΔKth的映射相关性比其他两种合金具有更高的准确性。通过对比疲劳裂纹来源和微观组织特征尺寸，定量得到了三种合金的DTS。当DTS分别控制在铸态AM60的37.1 μm、SLM-AlSi10Mg的89.0 μm和SLM-Ti6Al4V的75.3 μm内时，高周疲劳失效的概率仅为5%。95%概率估计值与平均缺陷大小之间的相对误差分别为25.8%，8.4%和4.6%。实验和文献数据验证了这些估计值的有效性和合理性。

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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.