Some notes on the results shown in the movies, which are predicted by using "Microstructure Simulator" developed by Converteam:

Top figure:
Temperature distribution through strip thickness and variation along the rolling line predicted from crop shear to FM exit pyrometer in a 6-stand hot strip finishing mill.

Before finishing rolling, a large temperature gradient exists between strip surface and centre. During hot rolling in the roll bite the surface temperature suffers a big drop due to roll contact chilling, while the central temperature increases considerably because of plastic deformation heat generation. A big surface temperature drop is also predicted when large interstand sprays are applied (see the results predicted for HSLA steel). With rolling progress in the finishing mill, the strip becomes thinner and thinner, and the temperature gradient between strip surface and centre becomes smaller and smaller.

Bottom figure:
Austenite grain size change predicted at different positions of strip thickness during hot strip finishing rolling of plain C-Mn steel and HSLA steels. The start grain size is assumed as 100 µm.

These grain size changes are the results of dynamic recrystallisation in the roll bite, and metadynamic recrystallisation, static recrystallisation and grain growth at the interstand time. Compared with plain C-Mn steel, a finer grain size is predicted at FM exit for HSLA steel, mainly due to the additions of microalloying elements (e.g. Nb, V, Ti) which retard the recrystallisation at the interstand time.

Results for C-Mn Steel
Results for HSLA Steel