High strength steel pipe for an air bag and a process for its manufacture

A process of manufacturing a high strength steel pipe for an air bag having excellent bursting resistance, characterized by producing a pipe from a steel material having a composition, in mass %, of:

• C:
• 0.05-0.20%, Si:
• 0.1-1.0%, Mn:
• 0.20-2.0%, P:
• at most 0.025%, S:
• at most 0.010%, Cr:
• 0.05-1.0%, Al:
• at most 0.10%,
• at least one of Mo:
• at most 0.50%, Ni:
• at most 1.5%, and B:
• at most 0.005%,
• and a remainder of Fe and impurities,
• then subjecting the steel pipe to cold working to obtain predetermined dimensions, then heating it to a temperature of at least the Ac1 transformation temperature followed by quenching, and then performing tempering at a temperature no higher than the Ac1 transformation temperature.

A process of manufacturing a high strength steel pipe for an air bag having excellent bursting resistance, characterized by producing a pipe from a steel material having a composition, in mass %, of:

• C:
• 0.05-0.20%, Si:
• 0.1-1.0%, Mn:
• 0.20-2.0%, P:
• at most 0.025%, S:
• at most 0.010%, Cr:
• 0.05-1.0%, Al:
• at most 0.10%,
• at least one of Mo:
• at most 0.50%, Ni:
• at most 1.5%, and B:
• at most 0.005%,
• at least one of Cu:
• at most 0.5%, Ti:
• at most 0.1%, and Nb:
• at most 0.1%,
• and a remainder of Fe and impurities,
• then subjecting the steel pipe to cold working to obtain predetermined dimensions, then heating it to a temperature of at least the Ac1 transformation temperature followed by quenching, and then performing tempering at a temperature no higher than the Ac transformation temperature.