Electric Resistance Welded Steel Pipe

摘要

An electric resistance welded steel pipe excellent in terms of fatigue strength. The steel pipe including a chemical composition containing, by mass %, C: 0.35% or more and 0.55% or less, Si: 0.01% or more and 1.0% or less, Mn: 1.0% or more and 3.0% or less, P: 0.02% or less, S: 0.01% or less, Al: 0.005% or less, N: 0.0050% or less, Cr: 0.1% or more and 0.5% or less, and the balance being Fe and inevitable impurities and a metallic microstructure including pearlite, ferrite, and bainite, in which the area ratio of the pearlite is 85% or more, the total of the area ratios (including 0) of the ferrite and the bainite is 15% or less, and in which a prior austenite grain size is 25 μm or more.

主权项

1. An electric resistance welded steel pipe, the steel pipe having a metallic microstructure including pearlite, ferrite, and bainite, and a chemical composition comprising:
C: 0.35% or more and 0.55% or less, by mass %; Si: 0.01% or more and 1.0% or less, by mass %; Mn: 1.0% or more and 3.0% or less, by mass %; P: 0.02% or less, S: 0.01% or less, by mass %; Al: 0.005% or less, by mass %; N: 0.0050% or less, by mass %; Cr: 0.1% or more and 0.5% or less, by mass %; and Fe and unavoidable impurities as a balance, wherein an area ratio of the pearlite is in the range of 85% or more, the total of area ratios (including 0) of the ferrite and the bainite is in the range of 15% or less, and a prior austenite grain size is in the range of 25 μm or more.