LOW CARBON ALLOY STEEL TUBE HAVING ULTRA HIGH STRENGTH AND EXCELLENT TOUGHNESS AT LOW TEMPERATURE AND METHOD OF MANUFACTURING THE SAME

A low carbon alloy steel tube and a method of manufacturing the same, especially for a stored gas inflator pressure vessel, in which the steel tube consists essentially of, by weight: about 0.06% to about 0.18% carbon, about 0.3% to about 1.5% manganese, about 0.05% to about 0.5% silicon, up to about 0.015% sulfur, up to about 0.025% phosphorous, and at least one of the following elements: up to about 0.30% vanadium, upto t about 0.10% aluminum, up to about 0.06% niobium, up to about 1% chromium, up to about 0.70 % nickel, up to about 0.70% molybdenum, up to about 0.35% copper, up to about 0.15% residual elements, and the balance iron and incidental impurities. After a high heating rate of about 100° C. per second; rapidly and fully quenching the steel tubing in a water-based quenching solution at a cooling rate of about 100° C. per second. The steel has a tensile strength of at least about 145 ksi and as high as 220 ksi and exhibits ductile behavior at temperatures as low as -100° C.