Seamless tube, especially airbag inflation unit housing, is produced from billet of low carbon steel of specified composition by piercing, cold drawing, annealing and cold drawing with small wall thickness reduction

摘要

Seamless tube production, by subjecting a billet of low carbon steel of specified composition to hot piercing, cold drawing, annealing and cold drawing with relatively small wall thickness reduction, is new. A seamless tube is produced from a cylindrical billet of low carbon steel, having the composition (by wt.) 0.07-0.15% C, 1-2% Mn, less than 0.02% P, less than 0.015% S, 0.5-2.10% Cr, 0.2-1.0% Ni, 0.2-0.7% Mo, less than 0.65% Cu, less than 0.25% residual elements and balance Fe, by (a) forming a cylindrical tube by piercing the billet at 1000-1300 deg C; (b) reducing the tube wall thickness by cold drawing; (c) annealing; and (d) cold drawing to achieve less than 26% wall thickness reduction. Preferred features: The produced tube is cut to length and welded to an end cap and an end wall made of the above low carbon steel.