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Mechanical Properties and Anisotropies of 0.2% Carbon Steel with Bimodal Microstructure Subjected to Heavy‐Reduction Controlled‐Rolling Process
Author(s) -
Park HyungWon,
Shimojima Kei,
Sugiyama Sumio,
Komine Hisanao,
Yanagimoto Jun
Publication year - 2016
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.201500294
Subject(s) - materials science , ductility (earth science) , microstructure , ultimate tensile strength , anisotropy , composite material , scanning electron microscope , fracture (geology) , elongation , tensile testing , dimple , stress (linguistics) , metallurgy , optics , linguistics , creep , physics , philosophy
The mechanical properties, anisotropies, and fracture behavior of 0.2% carbon steel sheets produced by a heavy‐reduction single‐pass controlled‐rolling process with approximately 75% thickness reduction are investigated via a tensile test, field‐emission scanning electron microscopy, and electron backscattering diffraction. The 900‐ and 1000 °C‐heated specimens with less well‐developed textures show relatively homogeneous anisotropies, whereas the 700‐ and 800 °C‐heated specimens show strong V‐shaped anisotropies, where the relative strength decreases and the relative elongation increases at 45° from the rolling direction in comparison with other directions. The uniform and total elongations of the 900‐ and 1000 °C‐heated specimens in their rolling direction of roughly 12–14% and 23–28% are higher than those of the 700‐ and 800 °C‐heated specimens, respectively, while maintaining high strength (610–670 MPa), as clarified from the nominal stress–strain curves. Additionally, the bimodal structure on the fracture surface consisting of submicron‐size (<1 μm) and fine (2–5 μm) dimples lead to higher ductility while retaining outstanding strength. This is attributed to the submicron‐size grains having excessive strength and the micron‐size grains having high ductility.