| 摘要 |
The present invention provides the following: a thick steel plate in which in the tip shape of the long brittle fracture stopping area, in relation to a region having from 1/4 to 1/10 of the sheet thickness from the surface of the steel plate, a region comprising 20% of the sheet thickness of the central region of the sheet thickness forms a recess at least as long as the thickness of the plate in relation to the direction in which the long brittle fracture propagates, and the X-ray intensity ratio of the (211) plane or the (100) plane of the rolled surface region of at least 20% of the sheet thickness region in the central region of the sheet thickness is 1.5 or greater and the X-ray intensity ratio of the region having 1/4 to 1/10 of the sheet thickness or of the (110) plane of the rolled surface having 3/4 to 9/10 of the sheet thickness is 1.3 or higher; a steel plate manufacturing method wherein steel of specific constituent elements, after being heated to 900 to 1350°C, is rolled at a surface temperature of 850 to 1000 °C and a cumulative reduction ratio of 10% or greater, and then, when the steel plate surface temperature is 550 to 800 °C after completion of rolling at a specific surface temperature and internal temperature at a one pass rolling reduction of 7% or greater and a cumulative reduction ratio of 50% or greater, is hot rolled; and a method for evaluating long brittle fracture propagation stopping performance and an evaluation apparatus for the same. |
