| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a steel sheet or a steel slab for a high strength sour resistant line pipe, for which a concentration mapping analysis in a region including the center segregation part is carried out for center segregation of continuously cast slab and a thick steel sheet, and a correlation between the center segregation and the risk rate of crack of the steel sheet is obtained. <P>SOLUTION: The steel sheet or the steel slab for the high strength sour resistant line pipe is characterized in that the steel slab contains 0.03-0.07% C, 0.01-0.5% Si, 0.8-1.5% Mn, ≤0.07% Al, ≤0.010% P, ≤0.001% S and Ti, Nb, Ca, N, O and further, one or more kinds selected from among Cu, Ni, Cr, Mo, V; and three or less pieces of Mn-concentrated spots approximate to an elliptical shape are present in a measurement region of ±5 mm in the thickness direction per 100 mm length in the width direction of the steel sheet with the center part (t/2 part: t is the thickness of the steel sheet) of the cross section of the steel sheet vertical to the casting direction as a center, and the length of a major axis of the Mn concentrated spot exceeds >1.5 mm, and the Mn concentration is ≥1.6%. <P>COPYRIGHT: (C)2013,JPO&INPIT |
