Refinement of the Ti-17 microstructure after hot deformation: Coupled mesoscale model

0539463 - ÚJF 2022 RIV CH eng J - Journal Article
Buzolin, R. H. - Canelo-Yubero, David - Warchomicka, F. - Lasnik, M. - Krumphals, A. - Poletti, M. C.
Refinement of the Ti-17 microstructure after hot deformation: Coupled mesoscale model.
Materials Science and Engineering A Structural Materials Properties Microstructure and Processing. Roč. 800, JAN (2021), č. článku 140268. ISSN 0921-5093. E-ISSN 1873-4936
Institutional support: RVO:61389005
Keywords : static recrystallization * Ti-17 * strain induced boundary migration * mesoscale modelling * nucleation * grain growth * static recovery * in-situ sychotron * X-Ray diffraction
OECD category: Materials engineering
Impact factor: 6.044, year: 2021
Method of publishing: Limited access
https://doi.org/10.1016/j.msea.2020.140268

The thermo-mechanical processing of Ti-alloys comprises several steps where complex deformation and temperature cycles are achieved. In this work, the static recrystallization behaviour of a Ti-17 alloy is investigated using ex-situ characterization and in-situ synchrotron radiation experiments aiming to understand the operating mechanisms and to establish the recrystallization kinetics. Hot compression in the 13field for different strain rates is applied to provide different initial microstructures before isothermal heat treatments and continuous cooling. Strain induced boundary migration is the main operating nucleation mechanism during static recrystallization. A simple mesoscale model is proposed to couple the evolution of the microstructure during hot deformation followed by annealing considering the heterogeneity of deformation within the 13 -grains, for the nucleation and growth of grains and the formation of the substructure by static recovery. Electron backscattered diffraction measurements are used after isothermal annealing and continuous cooling treatments to validate the model. A strong influence of the localization of deformation in the vicinity of the prior 13 -high angle grain boundaries is observed and empirically implemented in the mesoscale model. The strong influence of the temperature is attributed to the difference in high angle grain boundary mobility during static recrystallization. Grain refinement is not successfully achieved up to the investigated strain due to the insufficient nucleation rate with respect to the growth rate. However, a homogenous recrystallized microstructure is observed. The model can predict the microstructure for any starting microstructure, even beyond the experimental validation.
Permanent Link: http://hdl.handle.net/11104/0317201