Cryogenic impact and fatigue properties of additively manufactured CrCoNi medium entropy alloy

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue Pub Date : 2024-12-13 DOI:10.1016/j.ijfatigue.2024.108767

Sun-Kwang Hwang, Minh Tien Tran, Cong Hoang Dang, Jeong-Min Heo, Ho Won Lee, Kyung-Hwan Jung, Dong-Kyu Kim

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引用次数: 0

Abstract

For structural applications subjected to rapid and cyclic loading, impact toughness and fatigue strength are critical properties that determine material suitability. CrCoNi medium entropy alloys (MEAs) have garnered attention due to their exceptional mechanical properties. Therefore, it is essential to assess the structural integrity of this alloy under harsh environments. This study investigates the impact and fatigue properties of CrCoNi MEA processed via laser powder bed fusion (LPBF) at both room and cryogenic temperatures. Charpy V-notch impact tests were conducted at 298 K, 200 K, and 77 K, while high-cycle fatigue tests were performed at 298 K and 150 K. The results show exceptional impact toughness at all temperatures, although toughness decreases as temperature drops. At 298 K, Charpy impact specimens exhibit more significant deformation, with cracks primarily following grain boundaries, while at 200 K and 77 K, trans-granular cracking dominates. Additionally, fatigue properties of LPBF CrCoNi MEA at 150 K show significant improvement compared to those at 298 K, attributed to the higher density of deformation twins forming at lower temperature during fatigue. These findings demonstrate that LPBF CrCoNi MEA offers a promising combination of impact and fatigue properties at cryogenic temperatures, suggesting its suitability for cryogenic applications.

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添加制造的铬钴镍中熵合金的低温冲击和疲劳性能

对于承受快速和循环载荷的结构应用而言，冲击韧性和疲劳强度是决定材料适用性的关键性能。铬钴镍中熵合金（MEA）因其优异的机械性能而备受关注。因此，评估这种合金在恶劣环境下的结构完整性至关重要。本研究调查了在室温和低温条件下通过激光粉末床熔融 (LPBF) 加工的铬钴镍 MEA 的冲击和疲劳性能。在 298 K、200 K 和 77 K 下进行了夏比 V 型缺口冲击试验，在 298 K 和 150 K 下进行了高循环疲劳试验。结果表明，尽管韧性会随着温度的降低而降低，但在所有温度下都具有优异的冲击韧性。在 298 K 时，夏比冲击试样表现出更明显的变形，裂纹主要沿着晶界产生，而在 200 K 和 77 K 时，跨晶粒裂纹占主导地位。此外，与 298 K 时相比，150 K 时 LPBF 铬钴镍 MEA 的疲劳性能有了显著改善，这归因于疲劳期间在较低温度下形成的变形孪晶密度更高。这些研究结果表明，LPBF 铬钴镍 MEA 在低温条件下具有良好的冲击性能和疲劳性能，因此适合低温应用。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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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.