공정 파라미터 최적화 및 유한 요소 모델링을 이용한 SS400강 압출재의 열간 변형 거동 연구

초록

Hot deformation behavior of SS400 steel was investigated by isothermal compression tests under the condition of temperature range of 700-1000 ℃ and strain rate range of 0.001-1 s-1. The constitutive equation derived using the flow stress and Zener-Hollomon parameter was proposed to predict the flow stress, and the actual experimental value and the predicted value showed high agreement. The flow stress behavior of SS400 material was shown through a processing map based on a dynamic material model, and the effect of dynamic recrystallization volume fraction and grain boundary on flow stress was confirmed through microstructure comparison in stable and unstable process conditions. The extruded material was manufactured reflecting the optimized process conditions, and the microstructure and mechanical properties of the manufactured material were observed and evaluated. The finite element method modeling to which the derived constitutive equation was applied predicted the distribution of the effective strain of the extruded material, and the correlation between the difference in grain size and Vickers hardness value and the effective strain value according to the position of the extruded material was identified.

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