Dynamic Transformation During the Torsion Simulation of Plate and Strip Rolling
Torsion simulations of plate and strip rolling were carried out on a plain C–Mn and an X70 Nb steel over the temperature range 900–1000 °C. Pass strains of 0.4 were applied at a strain rate of 1 s−1. Interpass times of 0.5, 1, 1.5, 3, 10, and 20 s were employed to determine the mean flow stresses (MFSs) applicable to plate and strip rolling. By means of double differentiation, critical strains of 0.05 and 0.12 were established for the initiation of dynamic transformation and dynamic recrystallization, respectively. It is shown that the dynamic transformation of austenite to ferrite takes place above the Ae3 temperature, resulting in significantly lower than expected MFS values. The nucleation and growth of ferrite reduces the rolling load and modifies the microstructure. Shorter interpass times produce larger decreases in MFS than longer ones because they do not permit as much retransformation to austenite as takes place during longer interpass intervals.
KeywordsStrip mill simulation Plate mill simulation Dynamic transformation
The authors acknowledge with gratitude funding received from the McGill Engineering Doctoral Award (MEDA) program, the Brazilian National Council for Scientific and Technological Development (CNPq), and the Natural Sciences and Engineering Research Council of Canada.
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