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Vol.42, No.7, 543 ~ 552, 2004
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| Title |
| Effects of Ferrite Grain Size and Martensite Volume Fraction on Quasi-static and Dynamic Deformation Properties of 0.15C-2.0Mn-0.2Si Dual Phase Steels |
| 황병철 Byoung Chul Hwang , Tong You Cao , 신상용 Sang Yong Shin , 이성학 Sung Hak Lee , 김성준 Sung Joon Kim |
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| Abstract |
| Effects of ferrite grain size and martensite volume fraction on quasi-static and dynamic deformation behavior of dual phase steels were investigated in this study. Dynamic torsional tests were conducted on six steel specimens, which had different ferrite grain size and martensite volume fraction, using a torsional Kolsky bar. Under a dynamic loading condition, maximum shear stress and fracture shear strain increased with decreasing the ferrite grain size and increasing the martensite volume fraction. Observation of the deformed area beneath fracture surface after the dynamic torsional test indicated that adiabatic shear bands of 5-15 μm in width were formed along the shear stress direction; voids or microcracks initiated at martensite/ferrite interfaces below the shear band. The width of the shear band decreased with increasing ferrite grain size and with decreasing martensite volume fraction. These phenomena were then analyzed by introducing concepts of critical shear strain. (Received April 7, 2004) |
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| Key Words |
| Dual phase steel, Dynamic deformation, Martensite volume fraction, Ferrite grain size, Step quenching |
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