Abstract
The high-temperature mechanical properties and microstructure of forging billets of C-Si-Mn-Cr and C-Si-Mn-Cr-Mo ultra-high-strength cold-rolled steels (tensile strength≥1000 MPa, elongation≥10%) were studied. Through the comparison of reduction in area and hot deformation resistance at 600–1300°C, the Mo-containing steel was found to possess a higher strength and a better plasticity than the Mo-free one. The equilibrium phase diagram and atom fraction of Mo in different phases at different temperatures were calculated by Thermo-Calc software (TCW). The results analyzed by using transmission electron microscopy and TCW show that precipitates in the Mo-containing steel are primarily M23C6, which promote pearlite formation. The experimental data also show that a lower ductility point existing in the Mo-free steel at 850°C is eliminated in the Mo-containing one. This is mainly due to the segregation of Mo at grain boundaries investigated by electron probe microanalysis (EPMA), which improves the strength of grain boundaries.
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This work was financially supported by the National High-tech Research and Development Program of China (No.2009AA03Z518).
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Han, Qh., Kang, Yl., Zhao, Xm. et al. High-temperature properties and microstructure of Mo microalloyed ultra-high-strength steel. Int J Miner Metall Mater 18, 407–413 (2011). https://doi.org/10.1007/s12613-011-0454-5
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DOI: https://doi.org/10.1007/s12613-011-0454-5