Patent ID: 10738366

Abstract:
The present invention provides electric-resistance welded steel pipe optimal for applications such as production of shale gas which is comprised of steel having a chemical composition which contains, by mass %, respectively, C: 0.08 to 0.18%, Si: 0.01% to 0.50%, Mn: 1.30 to 2.1%, Al: 0.001 to 0.10%, Nb: 0.005 to 0.08%, and Ti: 0.005 to 0.03%, is limited to N 0.008% or less, P: 0.020% or less, and S: 0.010% or less, and has a balance of Fe and unavoidable impurities, wherein a structure at a center part of thickness is 40% to 70% by area of ferrite phase having a circle-equivalent diameter of 1.0 μm to 10.0 μm and a balance of a low temperature transformation phase comprising a bainite phase, and Ceq satisfies 0.32≤Ceq≤0.60.