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

摘要

PURPOSE:To make the production of not only a cold-rolled steel srip for working but also a high tensile cold-rolled steel strip possible by forming a cooling tank by immsersion in hot water as a primary cooling zone after a soaking zone into vertical type, and providing injecting devices under hot water, and control devices for immersion length of the steel strip and bath temp. CONSTITUTION:A cooler of a primary cooling zone of titled installation consisting of respective zones of heating, soaking, primary cooling, overaging, secondary cooling and post-treatment consists of one immersion tank 21 for hot water. The tank 21 is provided with a device 22 for turning the steel strip and under water injection headers 23. Water baths W, W' controlled at around b.p. and 70 deg.C with a control device for bath temp. are contained therein. In the stage of producing a cold rolled strip for working, the bath W is used and the immersion length of the strip S is controlled by moving the level L of the bath upward or downward or moving the device 22 upward or downward, whereby the end point temp. of cooling is controlled. The strip is cooled with the static boiling bath without operating the headers 23. In the case of producing a high tensile cold rolled strip, the bath W' is used, and the headers 23 are operated so that the strip is cooled immediately down to temp. lower than the Ms point by hot water jet cooling.