Fatigue crack propagation behavior and damage mechanism of Ti-Mo-Cr-V-Nb-Al alloy in the near-threshold region

IF 6.8 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue Pub Date : 2025-07-31 DOI:10.1016/j.ijfatigue.2025.109209

Rui Hu , Wangjian Yu , Guoqiang Shang , Gang Ran , Hong Wang

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引用次数: 0

Abstract

To meet the requirements of damage tolerance design for high-strength and high-toughness metastable β titanium alloys, it is of vital significance to regulate and obtain an appropriate microstructure for enhancing the fatigue resistance of such titanium alloys. This work mainly conducts a comparative study on the fatigue crack growth threshold value ΔK_th of a novel high-strength and high-toughness Ti-Mo-Cr-V-Nb-Al titanium alloy with basketweave and bi-modal microstructures, exploring the influence of its microstructure on fatigue crack initiation and growth behavior and the corresponding damage mechanism. It is discovered that equiaxed α_P phases are more prone to causing crack deflection compared with coarse lamellar α_P phases. Furthermore, the crack resistance of this alloy mainly originates from the crack deflection induced by α_P phases and the crack tip blunting caused by α_S phases. Based on the analysis of crack growth paths and slip traces, it is considered that basal slip provides a favorable path for crack growth, while second-order pyramidal slip exhibits greater resistance to crack growth. Additionally, microplastic deformation occurs in the α phase at the crack tip, resulting in lattice rotation. The residual dislocations in the α phase at the crack tip indicate the existence of slip transfer. Meanwhile, the phase boundaries serve as both sources and barriers for dislocations, which may lead to crack propagation along the phase boundaries.

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Ti-Mo-Cr-V-Nb-Al合金近阈值区疲劳裂纹扩展行为及损伤机理

为满足高强高韧性亚稳态β钛合金损伤容限设计的要求，调节和获得合适的微观组织对提高亚稳态β钛合金的抗疲劳性能具有重要意义。本工作主要对一种新型高强高韧性Ti-Mo-Cr-V-Nb-Al编织和双模态组织的钛合金疲劳裂纹扩展阈值ΔKth进行对比研究，探讨其显微组织对疲劳裂纹萌生和扩展行为的影响及其损伤机理。结果表明，等轴αP相比粗层状αP相更容易引起裂纹偏转。该合金的抗裂性主要来源于αP相引起的裂纹偏转和αS相引起的裂纹尖端钝化。通过对裂纹扩展路径和滑移轨迹的分析，认为基底滑移为裂纹扩展提供了有利的路径，而二阶锥体滑移对裂纹扩展的阻力更大。此外，裂纹尖端的α相发生微塑性变形，导致晶格旋转。裂纹尖端α相的残余位错表明存在滑移传递。同时，相边界既是位错的来源，也是位错的屏障，这可能导致裂纹沿相边界扩展。

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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.