CONTINUOUS HEAT TREATMENT INSTALLATION FOR COLD-ROLLED STEEL STRIP FOR WORKING AND HIGH TENSILE COLD-ROLLED STEEL STRIP

摘要

PURPOSE:To make production of not only a cold-rolled steel strip for working but also a high tensile cold rolled steel strip possible by using plural vertical type cooling tanks by immersion in hot water for a primary cooling zone after a soaking zone, and providing control devices for immersion length, control devices for bath temp. and hot water injecting devices respectively in the front and rear stage tanks. CONSTITUTION:A cooler of a primary cooling zone of a titled installation consisting of respective zones for heating, soaking, primary cooling, overaging, secondary cooling and post treatments consists of hot water immersion tanks 21, 21a which are connected to each other. Both tanks are provided with turning devices 22, 22a for the steel strip. The tank 21a is provided with underwater injecting headers 23 on the descending pass. The water baths W, W' in the tanks 21, 21a are maintained approximately at around boiling point and 70 deg.C respectively by control devices for bath temp. Both tanks permit the adjustment of immersion length by vertical movements of the devices 22, 22a or the levels L, L' of the baths. In the stage of producing a cold rolled steel strip for working, the tank 21a is emptied and the steel strip is subjected to cooling of the controlled end point only in the static boiling bath W of the tank 21. In the stage of producing a high tensile cold rolled steel strip, the strip is cooled in the static boiling bath W of the tank 21; thereafter, the cooling in the rear stage is accomplished by cooling by immersion in hot water with the bath W' wherein the headers 23 of the tank 21a are operated.