Kenji Araki

Production and quality of hot-rolled steel sheets with excellent formability

Production de toles presentant une resistance a la traction de 300 MPa par degazage RH de lacier lors de son elaboration, et un laminage controle. Ce nouvel acier a de tres basses teneurs en C, Mn et N, ameliorant la ductilite

Development of Water Quenching Technique for Cold Rolled Steel Strip

Synopsis: The cause of deterioration in strip shape in the course of water quenching has been made clear, and the water quenching technique for steel strip has been developed. The deterioration of strip shape results from the uneven disappearing (particularly from the edge of strip) of vapour film on strip surface. In order to improve the shape, it is necessary to quench the strip under such a condition that vapour film is not formed. This condition can be realized by spraying water to the strip uniformly with the impinging pressure of over 15 cm aq. until the strip is cooled below the transition temperature from film boiling to nucleate boiling. This condition of jet stream of water can be industrialized by means of an appropriate arrangement of slit nozzles and the suitable control of water pressure in headers. The most important point in the nozzle arrangement is to make the intervals between nozzles less than those between nozzle plates and strip. The shape of quenched sheet can be improved to the same level as that of shipped cold rolled sheet through the appropriate control of quenching conditions.