Role of martensite hardness in governing tensile behavior and local stress states in ferrite/martensite dual-phase steels

被引：0

作者：

Zhang, Long ^{[1
]}

Li, Xiaohua ^{[2
]}

Ding, Ran ^{[1
]}

Zhang, Chuanyou ^{[3
]}

Xu, Bo ^{[3
]}

Liu, Jiangcheng ^{[3
]}

Zhao, Chunhui ^{[3
]}

He, Biao ^{[3
]}

Liu, Chenxi ^{[1
]}

Liu, Yongchang ^{[1
]}

机构：

[1] State Key Laboratory of High Performance Roll Materials and Composite Forming, School of Materials Science and Engineering, Tianjin University, Tianjin,300350, China

[2] School of Mechanical Engineering, Tianjin University of Technology and Education, Tianjin,300222, China

[3] Tianjin Pipe Corporation, Tianjin,300301, China

来源：

Materials Science and Engineering: A | 2025年 / 943卷

基金：

中国国家自然科学基金;

关键词：

Cracks - Damage tolerance - Dislocations (crystals) - Dual phase steel - Ferrite - Fracture - Hardness - Martensite - Phase interfaces - Plasticity - Strain measurement - Strain rate - Tensile strength;

D O I：

10.1016/j.msea.2025.148841

中图分类号：

学科分类号：

摘要：

This study examines the tensile and fracture characteristics of ferrite/martensite (F/M) dual-phase steels by using transmission electron microscopy (TEM), digital image correlation (DIC), and crystal plasticity finite element (CPFE) calculations, focusing on the role of martensite hardness modulation. Experimental results reveal a significant correlation between martensite hardness and both mechanical properties and damage progression mechanisms. The softer martensite phases effectively suppress crack initiation at ferrite-martensite interfaces. Decreasing martensite hardness enhances deformation compatibility between martensite and ferrite phases. This improved strain accommodation reduces the dislocation density generated in ferrite at equivalent strain levels, thereby diminishing the work hardening rate of the material. Fractographic analysis demonstrates that during deformation, dislocations generated in ferrite accumulate at ferrite/martensite interfaces, forming distinct substructures that ultimately initiate interfacial cracking. Our analysis of F/M interfacial cracking behavior reveals that relying solely on strain gradient considerations at the phase boundaries leads to incomplete fracture characterization, as the evolution of stress state must be fundamentally incorporated in the failure mechanism assessment. The interfacial dislocation accumulation elevates stress triaxiality at phase boundaries, significantly increasing the critical fracture strain. Reduced martensite hardness effectively lowers this stress triaxiality at ferrite-martensite interfaces within the ferrite matrix, consequently enhancing the critical fracture strain. This work proves that softening the hard phase (martensite) optimizes interfacial stress states, offering an effective microstructural design strategy to improve damage tolerance in dual-phase material systems comprising soft and hard constituents. © 2025 Elsevier B.V.

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