Effect of Dynamic Recrystallization on Microstructural Evolution during Strip Rolling

Abstract

In the absence of static recrystallization, dynamic recrystallization is the principal softening mechanism operating during strip rolling. This process takes place when the interpass time is short, there is little strain-induced precipitation, and the presence of alloying elements in solution retards static recrystallization. It can lead to austenite grain sizes below 5 μm and ferrite grain sizes of about 3 μm when cooling is carried out at ~10°C/s. Increasing the roughing-to-finishing delay time or the delay time between successive passes leads to an increase in the density of Nb(CN) precipitates, which in turn promotes the formation of pancaked austenite. When the latter structure is cooled, ~7 μm ferrite grain sizes are produced, which are coarser than the ferrite structures obtained from dynamically recrystallized austenite rolled over the same temperature range. © 1990, The Iron and Steel Institute of Japan. All rights reserved.