Extending the boundaries of mechanical properties of Ti-Nb low-carbon steel via combination of ultrafast cooling and deformation during austenite-to-ferrite transformation

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• 作者：Xiangtao Deng ; Tianliang Fu ; Zhaodong Wang…
• 关键词：Ti ; Nb bearing steel ; ultra ; fast cooling ; deformation ; precipitation behavior ; mechanical properties
• 刊名：Metals and Materials International
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：23
• 期：1
• 页码：175-183
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Metallic Materials; Operating Procedures, Materials Treatment; Magnetism, Magnetic Materials; Engineering Thermodynamics, Heat and Mass Transfer; Characterization and Evaluation of Materials; Continuu
• 出版者：The Korean Institute of Metals and Materials
• ISSN：2005-4149
• 卷排序：23

文摘

We underscore here a novel approach to extend the boundaries of mechanical properties of Ti-Nb low-carbon steel via combination of ultrafast cooling and deformation during austenite-to-ferrite transformation. The proposed approach yields a refined microstructure and high density nano-sized precipitates, with consequent increase in strength. Steels subjected to ultra-fast cooling during austenite-to-ferrite transformation led to 145 MPa increase in yield strength, while the small deformation after ultra-fast cooling process led to increase in strength of 275 MPa. The ultra-fast cooling refined the ferrite and pearlite constituents and enabled uniform dispersion, while the deformation after ultra-fast cooling promoted precipitation and broke the lamellar pearlite to spherical cementite and long thin strips of Fe_xC. The contribution of nano-sized precipitates to yield strength was estimated to be ~247.9 MPa and ~358.3 MPa for ultrafast cooling and deformation plus ultrafast cooling processes. The nano precipitates carbides were identified to be (Ti, Nb)C and had a NaCl-type crystal structure, and obeyed the Baker-Nutting orientation relationship with the ferrite matrix.