The Algoma Steel Corporation, Limited

Canadian Patents & Development Ltd.

Mcgill University

Ipsco Inc.

John J Jonas

Stephen Yue

Patrick J Hunt

George E Ruddle

Cheng-Kuei Jen

Jean F Bussiere

Philippe H Lequeu

Brigitte Bacroix

Irina D Makarow

Francisco Boratto

Abbas Najah-Zadeh

Lakshman N Pussegoda

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, are made of an alloy comprising, by weight, about 0.10% to 0.18% carbon, about 1.0% 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. Strains are applied to the shell in a stretch reducing mill below the T.sub.nr of the steel and above the A.sub.r3 to provoke dynamic recrystallization. The nitrogen and vanadium are preferably introduced to the steel during alloying in the form of a VN alloying agent. The vanadium, titanium and nitrogen are predominantly present as vanadium nitride and titanium nitride. The steel may also comprise 0.03% to 0.05% aluminum by weight.

Steel tube alloy

The strength of interstitial free steels is increased by up to 100% and the ductile to brittle transition temperature is decreased by up to 100.degree. C. by warm finish rolling in the single phase ferrite region below A.sub.rl to effect ferrite dynamic recrystallization of the steel microstructure to a ferrite structure of grain size having a grain size of up to 5 .mu.m, and especially an ultra fine grain size of 1 to 2 .mu.m; the method may be employed in various hot working methods including strip and rod mills, planetary hot rolling and extrusion.

Interstitial free steels and method thereof

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.

Seamless steel tube manufacture

A series of thermomechanical workings such as temperature-controlled torsional strains are applied to a specimen of steel at strain and temperature levels and interpass times selected to simulate rolling mill conditions. The measured stress values are compared with the temperatures of the steel during the working periods during which the respective values were obtained. Thermomechanical working schedules are repeated at selected varying starting and terminating temperatures thereby to obtain a series of possible rolling schedules. These simulations are selected so that a varying number of reduction passes in the sequence occur at steel temperatures below temperature A.sub.r3. The value of a selected parameter of the worked steel, e.g. yield strength, is measured at ambient temperature. From the rolling mill analogue of possible rolling schedule simulations, an optimized rolling schedule is selected which will predictably impart to the steel a value of the selected parameter falling within a predetermined range. Linear regression analysis is applied to empirically obtained rolling mill data to derive one or more linear relationships between a selected property (e.g. yield strength) of the steel and rolling mill parameters thereby to permit selection of an optimum rolling schedule suitable to obtain a preselected value of the selected property of the steel.

Steel rolling using optimized rolling schedule

A method of, and apparatus for, evaluating forming capabilities of metal plate by means of ultrasonic waves where the rolling direction and the density of the plate are known. The method comprises the steps of launching acoustic waves into the plate and detecting acoustic waves propagating in the plate to establish acoustic velocities in the plate along at least two different directions. Then the value of a certain plastic strain characteristic, like the average plastic strain ratio R or the planar strain ratio .DELTA.R, is determined from a previously established empirical relationship between the velocities and the value of the plastic strain ratio R(.alpha.).

Method of, and an apparatus for, evaluating forming capabilities of

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Westmount, Canada

John J Jonas