Investigating the Properties of Coil Tail in Ti–Nb–Mo Microalloyed Hot‐Rolled Strip. Issue 8 (31st May 2019)

• Record Type: Journal Article
• Authors: Gan, Xiaolong; Yuan, Qing; Zhao, Gang; Hu, Haijiang; Tian, Junyu; Xu, Guang
• Is Part Of: Steel research international. Volume 90:Issue 8(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-05-31
• Subjects: ferritic steel -- microalloy -- precipitates -- property -- Ti‐Nb‐Mo; Steel -- Periodicals; Steel -- Metallurgy -- Periodicals; 669.142
• DOI: 10.1002/srin.201900040
• Languages: English
• ISSNs: 1611-3683

Abstract

Abstract : 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. Abstract : The volume fractions of precipitates increase gradually from the outermost circle to the fifth circle of the strip coil, whereas no apparent discrepancy is noticed in the dimensions of precipitates. The precipitation strengthening induced by nano‐scale (Ti, Nb, Mo)C particles is the dominant factor for the disparity in properties in different positions of the coil tail.