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Hot Deformation Behavior and Microstructural Evolution of SA508‐IV Steel
Author(s) -
Dai Xin,
Yang Bin
Publication year - 2018
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.201800208
Subject(s) - materials science , dynamic recrystallization , softening , flow stress , strain rate , volume fraction , deformation (meteorology) , constitutive equation , composite material , grain size , hot working , thermodynamics , metallurgy , microstructure , physics , finite element method
The hot deformation behavior and microstructural evolution of SA508‐ІV steel are studied through hot compressive tests in the temperature range of 950–1250 °C, and in the strain rate range of 0.001–1 s −1 . The hot deformation activation energy and the stress exponent are calculated to be 328.73 KJ mol −1 and 3.29 by the regression analysis of sine hyperbolic function. On this basis, the constitutive Equations are developed. Moreover, the relationship between work hardening and dynamic softening is explained, and a two‐stage constitutive model is established to predict the flow stress of SA508‐ІV steel. The predicted and experimental values show a good consistency. Based on the conventional dynamic recrystallization kinetics model, the volume fraction of the dynamic recrystallization is also estimated, and the results show that the maximum fraction is close to 100% under the higher temperature and lower strain rate. Furthermore, the microstructural evolutions at different deformation conditions are also analyzed, and the DRX grain size has an exponential increase with increasing deformation temperature and decreasing strain rate.