Low carbon alloy steel tube having ultra high strength and excellent toughness at low temperature and method of manufacturing the same

Abstract

A low carbon alloy steel tube and a method of manufacturing the same, in which the steel tube consists essentially of, by weight: about 0.06% to about 0.18% carbon; about 0.5% to about 1.5% manganese; about 0.1% to about 0.5% silicon; up to about 0.015% sulfur; up to about 0.025% phosphorous; up to about 0.50% nickel; about 0.1% to about 1.0% chromium; about 0.1% to about 1.0% molybdenum; about 0.01% to about 0.10% vanadium; about 0.01% to about 0.10% titanium; about 0.05% to about 0.35% copper; about 0.010% to about 0.050% aluminum; up to about 0.05% niobium; up to about 0.15% residual elements; and the balance iron and incidental impurities. The steel has a tensile strength of at least about 145 ksi and exhibits ductile behavior at temperatures as low as −60° C.

Description

BACKGROUND OF THE INVENTION The present invention relates to a low carbon alloy steel tube having ultra high strength and excellent toughness at low temperature and also to a method of manufacturing such a steel tube. The steel tube is particularly suitable for making components for containers for automotive restraint systems, an example of which is an automotive airbag inflator. Airbag inflators for vehicle occupant restraint systems are required to meet strict structural and functional standards. Therefore, strict procedures and tolerances are imposed on the manufacturing process. While field experience indicates that the industry has been successful in meeting past structural and functional standards, improved and / or new properties are necessary to satisfy the evolving requirements, while at the same time a continuous reduction in the manufacturing costs is also important. Airbags or supplemental restraint systems are an important safety feature in many of today's vehicles. In...

AI Technical Summary

Benefits of technology

The present invention relates to a low carbon alloy steel tube suitable for cold forming having ultra high strength (UTS 145 ksi minimum), and, consequently, a very high burst pressure. Moreover, the steel has excellent toughness at low temper

Problems solved by technology

In the past, air bag systems were of the type employing explosive chemicals, but they are expensive, and due to environmental and recycling problems, in recent years, a new type of inflator has been developed using an accumulator made of a steel tube filled with argon gas or the like, and this type is increasingly being used.

These welds are highly critical and as such require considerable labor, and in certain insta