Structure of Austenite of Carbon Steels in High Speed Hot Working Processes

Model for Predicting the Microstructural Evolution of Extralow Carbon Steels

“…The previous investigation revealed that carbon content of between 0.05 % and 0.8 % hardly affects the evolution of the austenite microstructure 8) and this study confirms that C content of less than 0.05 % has similarly negligible influence on the evolution of austenitic microstructure, which means that the model developed for low carbon steel can also be applied to extra-low carbon steels. The equations used in the model are given in Table 2.…”

“…The inclination of the Avrami plots is around 2, which coincides with that in the case of low carbon steels. 7,8) Figure 3 shows a comparison of the experimental results of the time for 50 % recrystallization with that calculated via the model developed for low carbon steels, with the deformation conditions given in the figure. In this case, only static recrystallization occurred.…”

Numerical Analysis for the Prediction of Microstructure after Hot Forming of Structural Metals

“…Senuma and Yada 7,8) extensively investigated the measurement of the microstructural evolution of C-Si-Mn steels during hot compression, and they found equations on the kinetics of, for example, work hardening, dynamic and static recoveries, dynamic and static recrystallization and grain growth as functions of process variables such as temperature, strain rate and strain. 8) They proposed an analytical model to predict the flow stress and microstructural evolution, taking dislocation density as a representative variable.…”

“…8) They proposed an analytical model to predict the flow stress and microstructural evolution, taking dislocation density as a representative variable. 9) They also 10) Finite element analysis of the metal forming process propagated in the 1980s after the pace-setting investigations on microstructural evolution in the hot forming of structural metals by Sellars et al, 4,6) Laasraoui and Jonas, 5) Senuma and Yada [7][8][9][10] and other researchers. As finite element analysis can reveal the transient changes in temperature and strain rate at each point of the structural metal during forming, we need a new approach to reflect this transient change in process variables in the evolution of microstructure.…”

Incremental Formulation for the Prediction of Microstructural Change in Multi-pass Hot Forming.

“…Activation energy is Q=266 (KJlmol). Senuma et al 4) observed that grain growth during post-dynamic re- Vol. 39 (1999) …”