Patent ID: 8815024
Filing Date: 2014-08-26
Classification: C21D,C22C,Y10T

Abstract:
1. A steel pipe formed from a plate of a steel base material, wherein the steel base material comprises, by mass %, C: 0.03 to 0.30%, Si: 0.01 to 0.8%, Mn: 0.3 to 2.5%, P: 0.03% or less, S: 0.01% or less, Al: 0.001 to 0.1%, N: 0.01% or less, and a balance of iron and unavoidable impurities, wherein the steel pipe is heated in the austenite-ferrite dual-phase temperature region and is then quenched, wherein the heating and the quenching are conducted after the plate of the steel base material is shaped into the steel pipe, and wherein the steel pipe has: