| 摘要 |
Provided is a high-strength welded steel pipe for an airbag inflator, the pipe having high toughness and workability. A base material part in the present invention has: a composition including, in mass%, 0.02-0.08% C, 0.001-1.0% Si, 0.1-2.0% Mn, no more than 0.1% P, 0.01-0.1% Al, no more than 0.01% N, 0.01-0.20% Ti, and 0.01-0.50% V, the remainder comprising Fe and unavoidable impurities; and a structure in which a ferrite phase having an average particle diameter of 10 µm or less constitutes an area ratio of 90% or greater, and carbides based on Ti and V having an average particle diameter of 10 nm or less are dispersed in the ferrite phase. The base material part is high-strength, having a tensile strength TS of 780 MPa or greater, the strength-elongation balance TS × E1 thereof is 15,000 MPa% or greater, the difference ∆HV of the hardness of the base material part and the hardness of a weld part in terms of Vickers hardness is 60 points or less, and the softening width Ws in the circumferential direction of a softened part in which the difference in Vickers hardness with respect to the base material part is 30 points or greater is no more than 0.05 mm. |
