Stress-state dependence of dynamic strain aging: Thermal hardening and blue brittleness
来源期刊：International Journal of Minerals Metallurgy and Materials2021年第5期
论文作者：Wen-qi Liu Jun-he Lian
摘 要：This study aims to discover the stress-state dependence of the dynamic strain aging（DSA） effect on the deformation and fracture behavior of high-strength dual-phase（DP） steel at different deformation temperatures（25–400℃） and reveal the damage mechanisms under these various configurations. To achieve different stress states, predesigned specimens with different geometric features were used. Scanning electron microscopy was applied to analyze the fracture modes（e.g., dimple or shear mode） and underlying damage mechanism of the investigated material. DSA is present in this DP steel, showing the Portevin–Le Chatelier（PLC） effect with serrated flow behavior, thermal hardening, and blue brittleness phenomena. Results show that the stress state contributes distinctly to the DSA effect in terms of the magnitude of thermal hardening and the pattern of blue brittleness. Either low stress triaxiality or Lode angle parameter promotes DSA-induced blue brittleness. Accordingly, the damage mechanisms also show dependence on the stress states in conjunction with the DSA effect.
Wen-qi Liu1，Jun-he Lian1,2
1. Advanced Manufacturing and Materials, Department of Mechanical Engineering, Aalto University2. Impact and Crashworthiness Lab, Department of Mechanical Engineering, Massachusetts Institute of Technology
摘 要：This study aims to discover the stress-state dependence of the dynamic strain aging（DSA） effect on the deformation and fracture behavior of high-strength dual-phase（DP） steel at different deformation temperatures（25–400℃） and reveal the damage mechanisms under these various configurations. To achieve different stress states, predesigned specimens with different geometric features were used. Scanning electron microscopy was applied to analyze the fracture modes（e.g., dimple or shear mode） and underlying damage mechanism of the investigated material. DSA is present in this DP steel, showing the Portevin–Le Chatelier（PLC） effect with serrated flow behavior, thermal hardening, and blue brittleness phenomena. Results show that the stress state contributes distinctly to the DSA effect in terms of the magnitude of thermal hardening and the pattern of blue brittleness. Either low stress triaxiality or Lode angle parameter promotes DSA-induced blue brittleness. Accordingly, the damage mechanisms also show dependence on the stress states in conjunction with the DSA effect.
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