Timetal 834合金中温度范围（573 K↔723 K）热机械疲劳过程中裂纹萌生的循环变形行为和微观机制

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue Pub Date : 2025-03-07 DOI:10.1016/j.ijfatigue.2025.108924

R. Kumar , J. Bhagyaraj , E. Hari Krishna , S. Mukherjee , K. Prasad , S. Mandal

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引用次数: 0

摘要

本文研究了Timetal 834合金在中温度范围（即573 K↔723 K）下，顺时钟形金刚石（CD）和逆时针形金刚石（CCD）条件下的热机械疲劳（TMF）寿命。TMF试验在应变幅为Δεm/2 =±0.6%和±1.0%时进行，失效后，用电子背散射衍射（EBSD）和透射电子显微镜（TEM）技术对每个试样的微观结构进行了表征。TMF结果表明，在给定应变幅值下，CD条件下的寿命比CCD条件下的寿命短，这是由于每次循环中拉伸损伤的累积较大。局部平均误差分析证实，在给定应变幅值下，CD条件下的应变局部化比CCD条件下的应变局部化更大。在这项研究中，裂纹的萌生和相关的破坏机制也进行了研究。EBSD分析显示，在两种TMF条件下，初级α (αp)晶粒内部存在带状结构，其中应变局部化明显更大。TEM结果与EBSD结果一致，在αp晶界附近的凹陷处显示出密集的位错密度。断口形貌研究表明，裂纹起裂部位附近有面状αp晶粒。EBSD分析表明，晶面与α - p晶粒的应变定位有关，沿基面或棱柱面取向，具有高施密德因子。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

Cyclic deformation behavior and micro-mechanism of crack initiation during thermomechanical fatigue in an intermediate temperature range (573 K ↔ 723 K) in Timetal 834 alloy

查看原文本刊更多论文

Cyclic deformation behavior and micro-mechanism of crack initiation during thermomechanical fatigue in an intermediate temperature range (573 K ↔ 723 K) in Timetal 834 alloy

In this work, thermomechanical fatigue (TMF) life of Timetal 834 alloy is studied under clockwise diamond (CD) and counterclockwise diamond (CCD) conditions in the intermediate temperature range (i.e., 573 K ↔ 723 K). TMF tests were performed at strain amplitude of Δ

ε_{m}

/2 = ±0.6 % and ± 1.0 % and post-failure, microstructure of each specimen was characterized by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) techniques. TMF results show that life is shorter under CD condition than CCD one at a given strain amplitude due to accumulation of greater tensile damage during each cycle. The local average misorientation analyses confirm that strain localization is greater under CD condition than CCD one at a given strain amplitude. In this study, crack initiation and the associated failure mechanism are also investigated. EBSD analyses show band-like structure inside the primary alpha (α_p) grains where strain localization is substantially greater in both TMF conditions. TEM results corroborate with the EBSD findings and show dense dislocation density at the concavities around α_p grain boundaries. The fractography studies show faceted α_p grains near the crack initiation sites. EBSD analyses reveal that facets are interrelated with strain localization in α_p grains, oriented along basal or prismatic with high Schmid factor.

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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.