| 摘要 |
<p>A seamless steel tube for airbag accumulators which can be produced by normalizing heat treatment alone without quenching and tempering and has a tensile strength of 850MPa or above and burst resistance at-20°C. The seamless steel tube has a steel composition which contains by mass C: 0.08 to 0.20%, Si: 0.1 to 1.0%, Mn: 0.6 to 2.0%, P: 0.025% or below, S: 0.010% or below, Cr: 0.05 to 1.0%, Mo: 0.05 to 1.0%, Al: 0.002 to 0.10%, at least one member selected from among Ca: 0.0003 to 0.01%, Mg: 0.0003 to 0.01% and REM (rare earth elements): 0.0003 to 0.01%, and at least one member selected form between Ti: 0.002 to 0.1% and Nb: 0.002 to 0.1% and has a Ceq value of 0.45 to 0.63 as defined by the formula (1) and a mixed metal structure of ferrite and bainite: Ceq = C + Si/24 + Mn/6 + (Cr+Mo)/5 + (Ni+Cu)/15... (1) wherein each symbol of element represents the content of the element in % by mass.</p> |
