초록 ▼

An apparatus (10) includes a low-carbon steel tube (24). The low-carbon steel tube (24) yields plastically more than about 5% before fracturing at temperatures down to about −40° C. when stress is applied to the low-carbon steel tube sufficient to cause the low carbon steel tube to so yi

An apparatus (10) includes a low-carbon steel tube (24). The low-carbon steel tube (24) yields plastically more than about 5% before fracturing at temperatures down to about −40° C. when stress is applied to the low-carbon steel tube sufficient to cause the low carbon steel tube to so yield.

대표청구항 ▼

Having described the invention, the following is claimed: 1. An apparatus comprising a cold drawn induction-heated low-carbon steel tube, wherein the low-carbon steel tube is cold-drawn prior to induction heating, said low-carbon steel tube yielding plastically more than about 5% before fracturing

Having described the invention, the following is claimed: 1. An apparatus comprising a cold drawn induction-heated low-carbon steel tube, wherein the low-carbon steel tube is cold-drawn prior to induction heating, said low-carbon steel tube yielding plastically more than about 5% before fracturing at temperatures down to about −100° C. when stress sufficient to cause said low carbon steel tube to so yield is applied to said low-carbon steel tube, said low-carbon steel tube being formed from a low-carbon steel that consists essentially of, by weight, about 0.07% to about 0.12% carbon, about 0.70% to about 1.60% manganese, up to about 0.020% phosphorous, up to about 0.015% sulfur, about 0.06% to about 0.35% silicon, about 0.25% to about 1.20% chromium, up to about 0.65% nickel, about 0.20% to about 0.70% molybdenum, up to about 0.35% copper, about 0.02% to about 0.06% aluminum, up to about 0.05% vanadium, up to about 0.25% residual elements, and the balance iron. 2. The apparatus of claim 1, wherein said low-carbon steel tube has a tensile strength of at least about 130,000 psi, a yield strength of at least about 104,000 psi, and an elongation at break of at least about 14%. 3. The apparatus of claim 1, wherein the low-carbon steel tube is seamless. 4. A method comprising the steps of: casting a billet of low-carbon steel, said billet of low-carbon steel having a first diameter and consists essentially of, by weight, about 0.07% to about 0.12% carbon, about 0.70% to about 1.60% manganese, up to about 0.020% phosphorous, up to about 0.015% sulfur, about 0.06% to about 0.35% silicon, about 0.25% to about 1.20% chromium, up to about 0.65% nickel, about 0.20% to about 0.70% molybdenum, up to about 0.35% copper, about 0.02% to about 0.06% aluminum, up to about 0.05% vanadium, up to about 0.25% residual elements, and the balance iron; reducing the diameter of said billet of low-carbon steel by hot-rolling said billet, forming a tube having an annular wall by piercing said billet; reducing the thickness of said annular wall to a first thickness by cold drawing said tube, induction heating said tube after said cold drawing to form a low-carbon steel tube that yields plastically more than about 5% before fracturing at temperatures down to about −100° C. when stress sufficient to cause said low carbon steel tube to so yield is applied to said low-carbon steel tube. 5. The method of claim 4, wherein the step of induction heating consists of induction heating said tube to a temperature of about 900° C. 6. The method of claim 4, wherein the low-carbon steel tube has a tensile strength of at least about 130,000 psi, a yield strength of at least about 104,000 psi, and an elongation at break of at least about 14%.