Electric resistance welded steel pipe, method for producing the same, line pipe, and building structure

An electric resistance welded steel pipe comprising a base metal zone and an electric resistance welded zone, the base metal zone comprising:

• a chemical composition containing, by mass,
• C:
• 0.040% or more and 0.50% or less,
• Si:
• 0.02% or more and 2.0% or less,
• Mn:
• 0.40% or more and 3.0% or less,
• P:
• 0.10% or less,
• S:
• 0.050% or less,
• Al:
• 0.005% or more and 0.10% or less, and
• N:
• 0.010% or less, with the balance being Fe and incidental impurities;
• and
• a steel microstructure having:
• by volume, ferrite:
• more than 30%, and bainite:
• 10% or more, a total volume fraction of the ferrite and the bainite being 70% or more and 95% or less, with the balance being one or two or more phases selected from pearlite, martensite, and austenite;
• and
• when regions surrounded by boundaries between adjacent crystals having a misorientation of 15° or more are defined as crystal grains, an average size of the crystal grains is less than 7.0 μm, and a volume fraction of crystal grains having a size of 40.0 μm or more is 30% or less;
• wherein a compressive residual stress generated in inner and outer surfaces of the electric resistance welded steel pipe in an axial direction of the electric resistance welded steel pipe is 250 MPa or less.