Patent attributes
An airbag inflator bottle member comprising a tubular body having a reduced-diameter portion at an end portion for fitting an initiator or the like thereto in which the reduced-diameter portion has a good low temperature toughness comparable to that of the portion which is not reduced in diameter is manufactured by the following method. A steel tube having a composition comprising C: 0.05-0.20%, Si: 0.1-1.0%, Mn: 0.10-2.0%, Cr: 0.05-2.0%, sol. Al: at most 0.10%, Ca: 0.0003-0.01%, optionally one or more elements selected from Cu: at most 1.0%, Ni: at most 1.5%, Mo: at most 1.0%, V: at most 0.2%, Nb: at most 0.1%, and Ti: at most 0.1%, and a remainder of Fe and impurities in which P: at most 0.025% and S: at most 0.010% is subjected to cold working, then it is cut to a predetermined length, and the cut steel tube is subjected to reducing in at least one end portion thereof and then to quenching and tempering.
