Variant Selection Behavior of Acicular Ferrite for Low-Carbon, Nb-bearing Ferrous Alloy Under Isothermal Transformation

• Published in: Metals and materials international 2024, 30(6), , pp.1635-1645
• Main Authors: Li, G. Q., Hou, Y. W., Hu, W. L., Zhao, J. H., He, W. W., Zhang, K. W., Ma, L. F.
• Format: Article
• Language: English
• Subjects: Bainite; Bearing alloys; Carbon content; Characterization and Evaluation of Materials; Chemistry and Materials Science; Cooling; Cooling rate; Crystallography; Engineering Thermodynamics; Ferrite; Ferrous alloys; Heat and Mass Transfer; Heat treating; Machines; Magnetic Materials; Magnetism; Manufacturing; Materials Science; Metallic Materials; Microstructure; Niobium; Processes; Solid Mechanics; Transformation temperature; 재료공학
• ISSN: 1598-9623; 2005-4149
• DOI: 10.1007/s12540-023-01585-6

To illuminate the variant selection discipline of acicular ferrite (AF) in regard to low-carbon niobium-bearing ferrous alloy (Nb-bearing alloy), isothermal transformation experiments under different cooling rates were carried out nearby the bainite start transformation temperature, and the crystallographic feature of the variant during AF transformation were characterized, systematically. The influences of cooling rate together with grain shape of parent austenite (PA) on the variant selection behaviors were further investigated. Results indicated that the transformation stasis phenomenon was obvious for the Nb-bearing alloy at the isothermal transformation temperature of 610 ℃ and cooling rate ranging from 1 to 30 ℃/s. The distribution feature of overall variants involved in the complex microstructure could be divided into two categories regardless of the variant type. One category was characterized by weak distribution at dispersed variant, and the other category was distributed following the feature of strong component distribution in local variant in accordance with the statistic. The morphology and crystallographic orientation (COR) of PA before AF transformation were the predominant factor determining the behavior and discipline of AF variant selection. This discipline obtained in this study indicated that it was possible to understand and control the transformation process of AF from perspectives of microstructure and variant selection. Graphical abstract