Hollow stabilizer for electric-resistance welded steel pipe having excellent fatigue durability

摘要

PROBLEM TO BE SOLVED: To provide a resistance welded tube for hollow stabilizer, excellent in fatigue endurance and having high strength.;SOLUTION: This steel tube has a composition containing 0.03-0.10% C, 0.20-1.0% Si, 1.0-2.5% Mn, ≤0.03% P, ≤0.005% S, ≤150 ppm of N+O, 0.02-0.20% Ti, 0.02-0.10% Nb, 0.01-0.1% total Al, 0-0.0050% B, 0-0.0050% Ca, and 0-0.30% Cr and also has a mixed structure where fine ferrite of ≤107 μm ferrite grain size and pearlite are present as a mixture. Further, the hardness of a resistance welded zone including heat-affected zone is regulated to ≤400 HV, and hardness difference Δ HV between maximum hardness and minimum hardness is regulated to ≤50 HV. It is preferable to regulate the tensile residual stress of outside surface to ≤300 N/mm2 and also the surface roughness to ≤Ry 10 μm by maximum height.;COPYRIGHT: (C)2000,JPO