Fatal defect determination and nanotwin-assisted early damage in ultra-high cycle fatigue of additively manufactured titanium alloy

IF 7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue Pub Date : 2026-06-01 Epub Date: 2026-01-14 DOI:10.1016/j.ijfatigue.2026.109491

MingHui Dai , Kun Yang , Xue Li , YaoHan Du , HaiTao Zhu , HongPing Zhang , JingJiang Wei , ChengLai Xin , QingYuan Wang

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引用次数: 0

Abstract

Additively manufactured (AM) titanium alloys have attracted wide attention due to their high specific strength and excellent corrosion resistance. However, fatal AM defect determination before fatigue loading and defect-induced early damage mechanism in the ultra-high cycle fatigue (UHCF) regime have been studied rarely. In this study, ultrasonic fatigue tests were carried out to study the UHCF behavior of AM Ti-6Al-4V (Ti64) alloy with low porosity (0.002 %). As a result, the difference in the crack initiation location doesn’t cause a significant difference in fatigue life. The lack of fusion defects are responsible for fatigue failure. Fatigue failure is not necessarily induced by the largest defect in size, but also depends on the location and shape of defects. The defect shape is considered to develop the new Y-parameter model, which can better predict fatigue life and determine the fatal defect before fatigue loading. During the early damage process, many {10–11} compressive nanotwins are generated, and which assist lath refinement to nanoparticles near the crack tip. Discontinuous intergranular microcracks prevail, microcrack evolution is accompanied by grain refinement.

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增材制造钛合金超高周疲劳致命缺陷确定及纳米孪晶辅助早期损伤

增材制造钛合金因其高比强度和优异的耐腐蚀性而受到广泛关注。然而，对AM材料疲劳加载前致命缺陷的确定和超高周疲劳状态下缺陷诱发的早期损伤机制的研究却很少。通过超声疲劳试验研究了低孔隙率（0.002%）AM Ti-6Al-4V （Ti64）合金的UHCF行为。结果表明，裂纹起裂位置的差异不会导致疲劳寿命的显著差异。缺乏熔合缺陷是造成疲劳失效的主要原因。疲劳失效不一定是由最大缺陷的尺寸引起的，还取决于缺陷的位置和形状。考虑缺陷的形状，建立了新的y参数模型，该模型能较好地预测疲劳寿命，并在疲劳加载前确定致命缺陷。在早期损伤过程中，产生了许多{10-11}压缩纳米孪晶，这有助于板条细化到裂纹尖端附近的纳米颗粒。晶间微裂纹以不连续为主，微裂纹演化伴随着晶粒细化。

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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.