Patent ID: 8562762

Claim:
High strength hot rolled steel product for line-pipes, comprising, by mass %, C: 0.01 to 0.1%, Si: 0.05 to 0.5%, Mn: 1 to 2%, P: ≦0.03%, S: ≦0.005%, O: ≦0.003%, Al: 0.005 to 0.05%, N: 0.0015 to 0.006%, Nb: 0.005 to 0.08%, and Ti: 0.005 to 0.02%, where N−14/48×Ti>0% and Nb−93/14×(N−14/48×Ti)>0.005%, and a balance of Fe and unavoidable impurities, wherein the steel product is in the form of a steel plate having a continuously cooled transformed structure microstructure and a thickness of 14 mm or more, a reflected X-ray intensity ratio, {211}/{111}, of the {211} plane and {111} plane parallel to the plate surface in the texture at the center of plate thickness of 1.1 or more, and an in-grain precipitate density of the precipitates of Nb and/or Ti carbonitrides of 10 17 to 10 18 /cm 3 .