A METHOD FOR MANUFACTURING HOT ROLLED STEEL SHEET FOR LINEPIPE HAVING LOW YIELD RATIO AND EXCELLENT YIELD STRENGTH ANISOTROPIC PROPERTIES

摘要

Mainly used for construction, offshore structures and line pipes, there is provided a method for producing a hot rolled steel sheet having an anisotropy of resistance yield ratio and excellent yield strength.;The hot rolled steel sheet is in weight%, C: 0.03 to 0.09%, Si: 0.01 to 0.5%, Mn: 1.2 to 2.0%, P: 0.01% or less, S: 0.001% or less, Ti: 0.01 to 0.1%, N: Less than 0.01%, Nb: 0.04 to 0.07%, Ni: 0.1 to 0.5%, Mo: 0.1 to 0.5%, steel slab composed of the remaining Fe and other unavoidable impurities is reheated at a temperature of 1100 to 1150 ° C. for 150 to 200 minutes Then, hot-rolled at a finish rolling temperature of 720 ~ 820 ℃, and then cooled by water and wound at a temperature of 500 ~ 600 ℃.;According to the present invention, it is possible to provide a hot rolled steel sheet having a tensile strength of 7200 MPa or more, a resistance yield ratio and excellent yield strength anisotropy.;Line pipe, hot rolled steel, yield strength anisotropy, resistive ratio, ferrite