Patent ID: 8641836
Filing Date: 2014-02-04
Classification: C21D,C22C

Abstract:
1. Steel plate for line pipe having a steel composition containing, by mass %, C: 0.07 to 0.15%, Si: 0.05 to 0.60%, Mn: 0.80 to 1.80%, P: 0.020% or less, S: 0.010% or less, Nb: 0.01 to 0.08%, and Al: 0.003 to 0.08%, having a balance of iron and unavoidable impurities, and having a value of Ceq shown by the following formula <1> of 0.48 or less, comprised of a mixed structure of ferrite and pearlite or ferrite and pearlite partially containing bainite in which a ferrite percentage is 60 to 95%, having a yield strength of 450 MPa or more and a total elongation of 20% or more, and having an amount of hydrogen contained in the steel of 0.1 ppm or less: