Electric resistance-welded steel tube for hollow stabilizer, hollow stabilizer, and manufacturing methods of same

An electric resistance-welded steel tube for a hollow stabilizer comprising:

• a base material portion;
• and
• a weld portion,
• wherein the base material portion contains, as chemical components, by mass %,
• C:
• 0.30% to 0.38%,
• Si:
• 0.15% to 0.30%,
• Mn:
• 1.20% to 1.50%,
• Al:
• 0.020% to 0.060%,
• Ti:
• 0.020% to 0.050%,
• B:
• 0.0010% to 0.0050%,
• Cr:
• 0.10% to 0.25%,
• Mo:
• 0% to 0.20%,
• Ca:
• 0.0005% to 0.0050%,
• Cu:
• 0% to 0.25%,
• Ni:
• 0% to 0.25%,
• V:
• 0% to 0.05%,
• N:
• 0.0060% or less,
• P:
• 0.020% or less,
• S:
• 0.0100% or less, and
• O:
• 0.0050% or less,
• a remainder includes Fe and impurities,
• a wall thickness of the base material portion is 2.0 to 6.0 mm, and an outer diameter of the electric resistance-welded steel tube is 10 to 40 mm,
• in a C direction cross section of the electric resistance-welded steel tube,
• a recessed bead cut is present in a region including the weld portion on an inner surface side of the electric resistance-welded steel tube,
• when an imaginary line is drawn from one opening edge to the other opening edge of the bead cut in a shortest distance, a maximum depth from the imaginary line to a bottom of the bead cut is 300 μm or less,
• a maximum inclusion diameter that is included in the base material portion is 300 μm or less,
• in the base material portion of the electric resistance-welded steel tube, a surface roughness of the inner surface side is 300 μm or less in terms of a maximum profile valley depth Rv, and
• maximum hardness of the electric resistance-welded steel tube including the weld portion is 300 Hv or less.