Method of manufacturing the excellent extra-thick martensitic stainless steel plate on the inner quality characteristics

摘要

PROBLEM TO BE SOLVED: To provide a production method of an extra thickness martensitic stainless thick steel plate excellent in an inner quality characteristic; and an extra thickness austenitic stainless thick steel plate excellent in the inner quality characteristic.SOLUTION: A production method of an extra thickness martensitic stainless steel palate of at least 80 mm thickness includes the following processes. 1: A process in which a slab by continuous casting is heated at 1010°C-1150°C, both ends of a crosswise direction of the slab is performed by forging draft from the crosswise direction, a slab width is shortened by at least 300 mm, and these both ends are thickened. 2: A process in which forging is performed to draft in a slab thickness direction by a draft ratio exceeding 10% at a temperature of at least Atransformation point (830°C). 3: A process in which the slab is heated at a range of 1090°C-1150°C, and rolling is performed by a working condition in which the total draft ratio in which a forging draft ratio and a rolling draft ratio in the 2 are summed is at least 20% and less than 60%. The extra thickness martensitic stainless steel plate is that a number of a porosity of a 0.1 mm&phgr;-1.0 mm&phgr; radius in a slab rolling vertical direction full width, and a board thickness of 1/2 thickness ±10 mm position is at most 10/100 mm.