Microstructure and bending fatigue behavior of martensite steel with 0.4%C subjected to different heat treatments

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue Pub Date : 2025-03-05 DOI:10.1016/j.ijfatigue.2025.108910

Jiaqiang Dang, Ryuji Yabutani, Sien Liu, Shoichi Nambu

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Abstract

The purpose of the present work was to analyze the microstructure evolution of martensite steel with 0.4C (in mass%) under different heat treatments which were marked as OQ900 and OQ1000, and its effect on fatigue fracture behavior. A crystal plasticity finite element method (CPFEM) was developed to analyze the role of multi-scale structures of lath martensite on fatigue crack initiation, and the fatigue lives of the materials with varying substructures are quantitatively compared. The numerical simulation was verified by fatigue tests where special attention was paid on the peculiarity of crack initiation exposed to the microstructural effect. The fracture surfaces of the steels subjected to both high-cycle fatigue (HCF) and low-cycle fatigue (LCF) regimes were also analyzed. The results indicated that OQ900 sample hold a smaller size in equivalent prior austenite grain, packet and block length than OQ1000 sample, which finally led to a slightly higher bending strength for OQ900 sample. Both inclusions and slipping fractures were found as the origins of fatigue crack initiation in the martensite steels with 0.4C, and especially the latter played a dominant role in HCF regime. In this regard, the difference in fatigue life tended clear as a clue to the effect of microstructure on fatigue behavior in HCF regime. The block morphology and its orientation affected the strain localization in an obvious way, where lower fracture indicator parameters (FIPs) value and longer crack initiation life were obtained in OQ900 sample. The EBSD analysis of fatigue-tested samples showed that the block boundaries were the most preferred sites for crack initiation, which were characterized as persistent slip bands. The crack propagation path was distributed in a deflected manner owing to the inhibition effect of boundaries. Overall, OQ900 sample presents a higher fatigue resistance than OQ1000 in HCF regime when the initiation and early propagation life of fatigue cracks were considered.

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含0.4%C的马氏体钢经不同热处理后的显微组织及弯曲疲劳行为

研究了0.4C（质量%）马氏体钢OQ900和OQ1000在不同热处理条件下的组织演变及其对疲劳断裂行为的影响。采用晶体塑性有限元法分析了板条马氏体多尺度结构对疲劳裂纹萌生的影响，并对不同亚结构材料的疲劳寿命进行了定量比较。通过疲劳试验验证了数值模拟的正确性，并特别注意了裂纹萌生的特殊性。同时对高周疲劳和低周疲劳两种状态下的断口进行了分析。结果表明，OQ900试样的等效先验奥氏体晶粒、包长和块长均小于OQ1000试样，从而使OQ900试样的抗弯强度略高于OQ1000试样。夹杂物和滑移断口都是0.4℃马氏体钢疲劳裂纹萌生的原因，其中滑移断口在HCF状态下起主导作用。在这方面，疲劳寿命的差异趋于清晰，这是微观结构对HCF状态下疲劳行为影响的线索。块状形貌及其取向对应变局部化影响明显，OQ900试样的断裂指示参数（FIPs）值较低，裂纹起裂寿命较长。疲劳测试样品的EBSD分析表明，块体边界是裂纹萌生的首选位置，其特征是持久的滑移带。由于边界的抑制作用，裂纹扩展路径呈偏转分布。综合考虑疲劳裂纹的萌生和早期扩展寿命，OQ900试样在HCF条件下的抗疲劳性能优于OQ1000试样。

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.