New plate property combinations as an outcome of the accelerated cooling process

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.