| 摘要 |
PROBLEM TO BE SOLVED: To provide a material with superior workability suitable for steel tubes used in air bag applications which require high strength and toughness as well as superior workability and weldability, and the production method of the same. SOLUTION: This highly tough steel tube for use in air bag applications contains in terms of mass percent, 0.05-0.20% C, 0.50% or less Si, 0.50-2.00% Mn, 0.020% or less P, 0.020% or less S, 0.10% or less sol. Al, 0.10%-0.50% Mo, 0.10-1.00% Cr, 0.10-0.50% Cu and 0.005-0.050% Ti, and may contain, in addition, one or more of 0.10-0.50% Ni and 0.010-0.050% Nb when needed, with its austenitic grain size after quenching and tempering processes being 11.0 or more.
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