The production method of a steel plate of high strength welded structure for a

摘要

The production method of a steel plate of high strength for welded structure. The present invention relates to a method for efficient production of a steel sheet for a welded structure which is excellent in the toughness of the base metal and HAZ using actively you for the control of the microstructure.The heating is conducted by the predetermined conditions using a plate with a composition in which the content of C, the content of Mn, the content of Ti and the content of N satisfy predetermined conditions, the rolling mill roughing is conducted in which the rolling temperature, reduction of Lam. Inaction, and the time of interpasse each pass of rolling satisfy predetermined conditions.And the accelerated cooling is conducted below in which the average rate of cooling in the direction of the thickness is 5 198 C / s or more.It is preferable that the rolling finishing mill is conducted after the roughing and before the accelerated cooling, in which the temperature of rolling of each pass of rolling mill, the rolling reduction in each pass of rolling, and the cumulative reduction of lamination satisfaction Zem predetermined conditions. The heat treatment can be conducted after the accelerated cooling.The cooling water can be conducted after the rolling mill roughing, before the beginning of the rolling finishing, or between each pass of rolling mill in the rolling mill roughing mill and the finishing.