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Investigating the Properties of Coil Tail in Ti–Nb–Mo Microalloyed Hot‐Rolled Strip
Author(s) -
Gan Xiaolong,
Yuan Qing,
Zhao Gang,
Hu Haijiang,
Tian Junyu,
Xu Guang
Publication year - 2019
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.201900040
Subject(s) - materials science , electron backscatter diffraction , transmission electron microscopy , microalloyed steel , ferrite (magnet) , grain boundary , microstructure , precipitation , scanning electron microscope , metallurgy , crystallography , composite material , nanotechnology , austenite , physics , chemistry , meteorology
In the present study, the thermo‐mechanical controlled processing (TMCP) technology was applied to produce Ti–Nb–Mo microalloyed hot‐rolled steels. The strength at the tail of a strip coil is often found to be non‐uniform. The microstructural and the mechanical properties of the specimens in the outermost circle as well as in the third circle and the fifth circle from the outermost circle were analyzed in detail. The optical microscopy (OM) and the electron backscatter diffraction (EBSD) techniques are employed for the characterization of ferrite grains and grain boundaries. The precipitates were revealed by high‐resolution transmission electron microscopy (HR‐TEM) and energy dispersive spectroscopy (EDS). It is found that the precipitation strengthening induced by nano‐scale (Ti, Nb, Mo)C particles was the dominant factor for the disparity in properties in different positions of the coil tail. The volume fraction of nano‐scale (Ti, Nb, Mo)C particles increases from 0.220% in the outermost circle to 0.343% in the fifth circle. In addition, the lattice planes of (110)α and (100)(Ti, Nb, Mo)C followed a Baker‐Nutting orientation relationship. Nano‐scale (Ti, Nb, Mo)C particles mainly precipitated in ferrite grains during coiling and subsequent cooling. Furthermore, different cooling rates along the strip had inconspicuous influences on the grain size and lengths of ferrite grain boundaries.