Two-step continuous cooling heat treatment applied in a low carbon bainitic steel

• Autor(a) principal: Castro, Pedro José de
• Data de Publicação: 2021
• Outros Autores: Silveira, Antonio Carlos de Figueiredo, Ivaniski, Thiago Marques, Turra, Cristiano José, Epp, Jérémy, Rocha, Alexandre da Silva
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/219950
• topic: Aço-carbono; Tratamento térmico; Resfriamento; Low carbon bainitic steel; Heat treatment; Granular bainite; Lath-like bainite

Thermo-mechanical treatments using continuous cooling after forging are an established method for producing bainitic steels, mainly because of the elimination of energy intensive additional heat treatment processes. The cooling is usually employed in an uncontrolled manner in the industrial sector, which can be detrimental to the resulting microstructural morphology and, consequently, to the final product properties. In this study, a new controlled two-step cooling route based on the principles of bainitic displacive growth was designed and applied in a 0.18C (wt-%) steel. Inverse finite element method was used on the cooling data to obtain the evolution of temperatures for the samples during cooling, allowing to assess point to point cooling rates. Investigations via X-ray diffraction, optical microscopy analysis and hardness testing revealed a variation of bainitic morphology, namely, the transition from granular bainite to lath-like bainite with relatively high hardness and constituents/phase boundaries than the pre-treated microstructure.