Ref.: MmeCa09-035

Development of a User-Friendly Tool for Quantifying Phase Transformations during Continuous Cooling of Steels

Apresentador: Arthur Helfstein Moura

Autores (Instituição): Ribamar, G.G.(Universidade de São Paulo); Moura, A.H.(Universidade de São Paulo); Pereira, H.B.(Universidade de São Paulo); Goldenstein, H.(Universidade de São Paulo);

Resumo:
The study of phase transformation in metallic materials has been ongoing for many years, employing various techniques. Among these, the combination of dilatometric behavior and microstructural characterization stands out as one of the most robust and straightforward methods. Typically, two primary cycles are investigated in new metallic materials: isothermal heat treatment to construct time-temperature-transformation (TTT) curves, indicating the onset and completion of transformations and enabling the tracking of transformation extents, and continuous cooling to establish continuous cooling transformation (CCT) curves, revealing transformations occurring under specific cooling rates from intercritical or complete annealing temperatures. While CCT curves align closely with mainstream steel production practices and can predict formed phases, they fall short in quantifying the amount of each phase. Furthermore, interpreting a dilatometric cooling curve encompassing numerous phase transformations complicates the accurate determination of phase transformations. Consequently, few studies have focused on precisely determining and quantifying the phases transformed during cooling, with existing methodologies often deemed overly complex for practical use. Therefore, this study introduces a novel tool developed in a freely accessible open-source language to facilitate the identification and quantification of phase transformations during continuous cooling of steels based on established mathematical approaches from the literature. To validate the constructed model, a CCT diagram was conducted using a quench dilatometer with pearlitic rail steel, heated to 900°C and subsequently cooled at various rates. Phase transformations during the cooling process were computed by analyzing phase expansion and contraction, contributing to the refinement and validation of the model's findings. The resulting software, presented as an open-source project, requires only raw dilation data and information regarding the density of relevant constituents, offering a user-friendly solution for phase transformation analysis in steel materials.