Metal treatment – Process of modifying or maintaining internal physical... – Heating or cooling of solid metal
Patent
1991-07-28
1993-02-16
Yee, Deborah
Metal treatment
Process of modifying or maintaining internal physical...
Heating or cooling of solid metal
148654, C21D 810
Patent
active
051867699
ABSTRACT:
A method for producing seamless steel tubes suitable for use as grades of casing and line pipe having yield strengths in excess of 70,000 psi, without being heat treated. Such steels are made of an alloy comprising, by weight, about 0.10% to 0.18% carbon, about 0.10% to 2.0% manganese, about 0.10% to 0.16% vanadium, about 0.008% to 0.012% titanium and about 150 parts per million to 220 parts per million nitrogen, the balance comprising iron and incidental impurities. The subject method comprises the steps of alloying a steel of the aforesaid chemical composition, forming the steel into a billet of steel, reheating the billet in a reheating furnace, passing the billet through a piercing mill to form a steel shell, elongating the steel shell within a mandrel mill, and reducing the diameter of the elongated shell in a stretch reducing mill. Strains are applied to the shell in the stretch reducing mill below the T.sub.nr of the steel and above the A.sub.r3 to provoke dynamic recrystallization. The subject method may also include the steps of cooling the steel shell after it exits the mandrel mill to a temperature below its A.sub.r1 temperature, prior to reheating, and/or accelerated cooling (optional, special cooling may not be necessary for thinner walls) after exiting the stretch reducing mill at a rate between 3.degree. C. to 5.degree. C. per second. The nitrogen and vanadium are preferably introduced to the steel during alloying in the form of a VN alloying agent.
REFERENCES:
"Microalloyed Steel in Seamless Tube Production In Hungary" J. Buczko, May 1988.
"Recrystallization Controlled Rolling of Seamless Tubing", Barbosa et al., 1986.
"Comparison of Dynamic Recrystallization and Conventional Controlled Rolling Schedules by Laboratory Simulation", Pussegoda et al. Mar., 1991, The Iron and Steel Institute of Japan, vol. 31, No. 3, pp. 278-288.
"The Production of Fine Grained Polygonal Ferrite Structures In Seamless Tubing Using Recrystallization Controlled Rolling", Yue et al., AIME Iron and Steel Society Conference, Oct., 1986.
"Laboratory Simulation of Seamless Tube Piercing and Rolling Using Dynamic Recrystallization Schedules", Pussegoda et al. Metallurgical Transactions A., Jan., 1990, vol. 21 App 153-164.
"Pilot Scale Development of Ti-V-N Microalloy Steels For Seamless Tubular Products" Ruddle et al. 1990 Mechanical Working and Steel Processing Proceedings, pp. 375-390.
Hunt Patrick J.
Jonas John J.
Pussegoda Lakshman N.
Ruddle George E.
Yue Stephen
Barrigar Robert H.
The Algoma Steel Corporation Limited
Yee Deborah
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