Quantifying carbide size effects on strain localization and fracture mechanisms in martensitic steels
Journal of Materials Science and Technology, cilt.275, ss.37-48, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 275
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.jmst.2026.03.065
- Dergi Adı: Journal of Materials Science and Technology
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Compendex, ICONDA Bibliographic, INSPEC
- Sayfa Sayıları: ss.37-48
- Anahtar Kelimeler: Carbide fracture mechanisms, Crystal plasticity modelling, Focused ion beam, High-resolution digital image correlation, Strain evolution
- Kocaeli Üniversitesi Adresli: Evet
Özet
The mechanical performance of carbide-containing martensitic steels is governed by the interactions between strain localizations and micro-fractures at the scale of individual carbides, yet this interaction is most often described qualitatively without clear mechanistic thresholds. In this work, a quantitative and mechanistic assessment is presented to elucidate how carbide size controls strain localization and the resulting fracture mechanisms in M50 steel, used here as a model martensitic alloy. By combining in-situ high-resolution digital image correlation during tensile loading with focused ion beam cross-sectioning and crystal plasticity finite element simulations, local strain evolution is quantitatively captured, and the associated surface and subsurface damage mechanisms are resolved at the level of individual carbides and their surrounding matrix. The results demonstrate that shear band-carbide interactions govern strain localization and mediate a size-controlled transition in the deformation and failure behavior. Small, equiaxed MC carbides exhibit high mechanical compatibility with the martensitic matrix and predominantly accommodate deformation without fracture, whereas larger carbides promote intense subsurface stress concentrations that lead to interfacial decohesion or internal carbide fracture. A critical carbide size separating strain accommodation from fracture-dominated behavior is identified in the range of 0.91–1.69 μm. Statistical analysis further reveals that the critical fracture strain of carbides decreases systematically with increasing carbide size and approaches an asymptotic limiting value of approximately 0.90%. These findings establish a quantitative mechanistic framework linking carbide size, local strain partitioning, and subsurface fracture mechanisms in martensitic steels and provide guidance for microstructural design strategies aimed at improving damage tolerance and fatigue performance in carbide-strengthened bearing steels.