A Study on Integrating Deformation Induced Ferrite Transformation with Conventional Thermomechanical Controlled Processing at an Industrial Scale and the Associated Challenges

This study explores the integration of deformation-induced ferrite transformation (DIFT) with conventional thermomechanical controlled processing (TMCP) at an industrial scale and examines the associated challenges. Successfully scaling up from the laboratory, the combined process for plain carbon steel achieved yield strengths of 388 MPa from a level of 250 MPa, Charpy impact energy (CIE) of 104-120 Joules at 0 °C and 64–a98 Joules at − 20 °C (both up from 27 J), and improved elongation values of 35-46% compared to the previous 28%. For plain carbon steel with low carbon, yield strength achieved were 360-397 MPa, CIE ranged from 132-143 Joules at 0 °C and 100-108 Joules at − 20 °C, with elongation from 45-61%. The TMCP-DIFT integration effectively eliminated pearlitic banding, resulting in a microstructure with well-refined acicular constituents, including ferrite and ferritic bainite. Despite the challenge of increase in the final rolling temperatures (up to 884 °C) after very high % reduction in last finishing pass, affecting large-scale DIFT implementation, the process substantially improved microstructural refinement. Plate warpage at the cooling bed was resolved by holding plates just above 400 °C before hot plate leveling, ensuring optimal transformation and leveling.