A New View of the Grain-Coarsening Behavior of Austenite and the Role of High-Mobility Boundaries in Ti-Microalloyed Low-Carbon Steels




Abstract: The traditional view of the role of microalloying elements (MAE) has been widely accepted by their contribution on the structure-property relationship optimization through the grain size control during reheating and subsequent microstructural refinement of the austenite during thermo-mechanical processing. This work shows a systematic analysis of the austenite grain-boundary character distribution by Electron Backscattered Diffraction (EBSD) and Electron Microscopy techniques conducted on experimental Timicroalloyed low-carbon steels subjected to different isothermal heat treatments. The results obtained exhibited a strong correlation between the high-angle boundaries with misorientations between 20º and 45º and the estimated pinning forces exerted by TiN particles on austenite grain-boundary mobility. The fraction of these high-angle boundaries decreases with increasing temperature during isothermal heat treatments. These observations provide a new view of the unpinning mechanism of second-phase particles and the kinetics of austenite grain-coarsening behavior for different MAE contents.

Authors: Victor Blancas-Garcia, Enrique Garcia, and C. Isaac Garcia

Keywords: Ti-Microalloying; GBCD; Pinning; Grain-Boundary Mobility; Low-Carbon Steels

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Page Count

8 pages


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