An extensive amount of literature exists concerning the thermal modell
ing of flat rolled steel sheet for both the hot and cold processes. Th
is reflects the importance attached to being able to predict the tempe
rature profile down the mill from the furnace or continuous easter to
final coiling. From a metallurgical point of view, the whole process i
s thermally activated, requiring control within definite temperature b
ands and cooling rates in order to hit target properties. Of equal imp
ortance is roll thermal camber growth, which requires on line predicti
on and dynamic control to achieve strip shape and profile within toler
ance. These aspects are still actively researched, but what have recei
ved considerably less attention are the physics of the small scale hea
t transfer mechanisms and the links with traction in the roll gap. A c
onsideration is important since both thermal contact and friction are
bounding conditions to the process and together determine the strip fl
ow behaviour as it passes through the roll gap; the manner in which th
e strip material is worked directly determines product quality. These
issues are complicated by the presence of scale and entrapped fluid. F
or exam pie, the conductivity for the scale is considerably lower than
for the base material and scale breakup, because of surface expansion
, adds a random input to the conditions. Researchers have found from l
ow speed laboratory trials that the heat transfer coefficient can rapi
dly change along the arc of contact. It is sensitive to pressure, lubr
ication conditions, temperature, and process parameters such as strip
velocity and percentage reduction. For the present discussions, curren
t research on these focused aspects are reviewed, Finite element model
ling is also described which has been used to examine the roll gap con
ditions allowing for temperature dependent plasticity and material pro
perties, frictional heating, and volumetric fluxes arising from plasti
c work. This approach has offered a window on the process that is prac
tically extremely difficult to examine, particularly for present indus
trial production rates which are continuing to increase. The small sca
le numerical analysis of the surface interactions has allowed further
insight into the contact mechanisms of the process. (C) 1996 The Insti
tute of Materials.