Objective. Accelerated cooling with defined water cooling rates as part of
the thermomechanical rolling process has become an important process step i
n recent years for producing low-alloy high-strength steels with enhanced w
eldability for linepipe, offshore, shipbuilding and structural steelwork ap
plications. Described are the effect of on the use of the property potentia
l offered by steel as a material as well as the broader process-and test-re
lated possibilities resulting from upgrading or combining with measuring an
d control systems.
Summary. A high-pressure section has been integrated in the 1988-installed
Mulpic accelerated-cooling line at the plate mill of AG der Dillinger Hiitt
enwerke, providing the capability to achieve plate cooling rates after roll
ing that are comparable to these of a conventional quenching installation.
Accelerated cooling processes such as direct quenching or quenching and sel
f tempering consequently become possible for plate thicknesses greater than
12 mm. It is shown that such high-pressure cooling can be used to develop
further materials and extend the thickness range for thickwalled constructi
ons or linepipes. As a supporting measure in the water supply system upgrad
ing at the cooling line, the ratings of the roller table motors in this are
a were increased, thereby allowing plates up to 5 t weight per meter to be
moved or positioned in the cooling unit with centimetre accuracy. A new pla
te position control system makes it possible to control and document the op
erations for up to positioning 8 plates in the area of the finishing stand,
cooling line, hot leveller and cooling bed. A precise combination of tempe
rature measuring systems with the plate positioning control equipment has a
lso led to the development of the ATP process, for production-shop trials,
with which can be used for cost-efficient material development.