MANUFACTURE OF THICK STEEL PLATE SMALL IN DIFFERENCE OF MECHANICAL CHARACTERISTICS IN THE DIRECTION OF PLATE THICKNESS

摘要

PURPOSE:To reduce the difference in the mechanical characteristics of a thick steel plate in the direction of its plate thickness, at the time of manufacturing a thick carbon steel plate by hot rolling and subsequent accelerated cooling, by specifying its temp. conditions. CONSTITUTION:At the time of manufacturing a thick steel plate by subjecting the slag of a carbon steel or a low alloy steel, an accelerated cooling stage in which the surface temp. after the completion of the accelerated cooling is regulated to =400 deg.C and a recuperating stage in which the range of the recuperating temp. on the surface is regulated to 500 to 650 deg.C are repeatedly executed for = two times. In this way, a thick steel plate small in the difference of mechanical characteristics in the direction of its plate thickness can be manufactured, by which high strength and high toughness as well as smallness in the difference of mechanical characteristics in the direction of the plate thickness required for a thick steel plate of =40mum used for pressure vessels for medium- high temp. use, ocean structures or the like can be satisfied.