Ipsco Enterprises, Inc.

Other

Jonathan Dorricott

William R Frank

Laurie E Collins

Robert J Boecker

Joseph D Russo

Brian H Wales

Michael Ambrose Cooke

Dengqi Bai

James Asante

A process for enhancing precipitation strengthening in steel and for making a high-strength micro-alloy steel, and a steel made from the process. The process includes the step of deforming the steel containing a suitable precipitate strengthening substance, at a temperature at which the microstructure of the steel is essentially stable and at which those precipitation strengthening particles that form are of a desirable particle size for precipitation strengthening. Deforming the steel introduces dislocations in the crystal structure of the steel, which increases the kinetics of precipitation by increasing the number of precipitation nucleation sites and accelerating the rate of diffusion of the precipitate material. The steel may be deformed by bending or rolling the steel. Preferably the process also includes the step of cooling the steel at a rapid rate so as to minimize the formation of precipitate particles of a larger-than-desired size.

High-strength micro-alloy steel

Process for making high strength micro-alloy steel

Surface defects in rolled steel are remedied by quenching a surface layer of the steel product downstream of the caster and upstream of the reheat furnace by transversely differentiated quenching to match the transverse temperature profile of the steel product. The flow rate of the quench spray is differentially adjustable across the width and optionally the length of the steel product. An array of spray nozzles controlled in transversely or longitudinally arranged groups provides the quench spray.

Differential quench method and apparatus

An apparatus for providing a magnetic field in a casting mold to slow and redirect in a controllable fashion the flow of liquid steel exiting from a submerged entry nozzle into the casting mold uses selectable removable ferromagnetic and non-magnetic laminar elements stackable on the ends of core fingers in the vicinity of the poles of an electromagnetic yoke positioned adjacent the mold face. By selecting the type and location of the stackable elements on the ends of the fingers, one can modify the properties of the magnetic field permeating the interior of the mold. Optionally, independent field coils may be provided for energizing selected portions of the magnetic field core structure to provide further magnetic field control without having to remove and replace laminar elements.

Controllable variable magnetic field apparatus for flow control of molten steel in a casting mold

Surface defects in rolled steel are remedied by quenching a surface layer of the strand immediately downstream of the caster by transversely differential quenching to match the transverse temperature profile of the strand. The flow rate of the quench spray is differentially adjustable across the width and optionally the length of the strand. An array of spray nozzles controlled by groups provides the quench spray.

The in-line combination of a reversing rolling mill (Steckel mill) and its coiler furnaces with accelerated controlled cooling apparatus immediately downstream thereof and associated method permits steel to be sequentially reversingly rolled to achieve an overall reduction of at least about 3:1, imparted by a first reduction while the steel is kept at a temperature above the T,by the coiler furnaces so as to preserve an optimum opportunity for controlled recrystallization of the steel after each rolling pass, and a second reduction while the temperature of the steel drops from about the T,to about the Ar,. The second reduction is preferably of the order of 2:1 as a result of which the steel reaches a final plate thickness. The steel product then passes through the accelerated controlled cooling apparatus, preferably applying laminar flow cooling at least to the upper surface of the steel passing therethrough so as to reduce the temperature of the steel from about the Ar,to a temperature at least about 250&deg; C. to about 300&deg; C. or more below the Ar,at a cooling rate of at about 12&deg; C. to about 20&deg; C. and preferably about 15&deg; C. per second, thereby to achieve a preferred fine-grained predominantly bainite structure affording enhanced strength and toughness in the final steel product.

Steckel mill/on-line controlled cooling combination

A steel rolling mill including a Steckel mill is provided with an in-line upstream quench station located downstream of the caster and upstream of the reheat furnace, a shear located downstream of the Steckel mill, and a temperature reduction station downstream of the shear. The upstream quench station has spray nozzles that quench a surface layer of the steel to transform same from an austentitic to a non-austentitic microstructure. The shear provides a precise transverse vertical face on the leading end of the steel. The temperature reduction station applies cooling fluid to the rolled steel so as to obtain a preferred microstructure that may be either bainite or martensite. If bainite, the temperature reduction station includes laminar-flow cooling apparatus; if martensite, the station also includes an initial rapid quench, in which latter case the station is followed by a tempering furnace.

Method of producing martensite-or bainite-rich steel using steckel mill and controlled cooling

An apparatus for providing a magnetic field in a casting mold to slow and redirect in a controllable fashion the flow of liquid steel exiting a submerged entry nozzle in the casting mold using removable laminar elements arrangeable in a horizontal series of vertical stacked arrays in association with corresponding side-by-side laminar constituents of the magnetic field core, or independent field coils for energizing each laminar portion of the magnetic field core, or both. The removable elements are preferably stackable rectangular parallelepiped plates together forming selectably a portion or all of the poles of the core as they extend into proximity with the transverse mold sides at selected locations.

Controllable variable magnetic field apparatus for flow control of

An optimizing method for improving the efficiency of production is provided for a steel rolling mill using a Steckel mill to roll steel slab to end-product thickness, and associated downstream equipment of limited capacity to generate strip and/or plate end-product. The optimizing method allows for continuous processing of steel slab of a mass within the capacity limits of the Steckel mill and equipment upstream of the Steckel mill, but in excess of the capacity of the associated downstream equipment, by first rolling the slab in the Steckel mill to intermediate coilable thickness, and then severing the intermediate steel product to produce two derivative segments, one of a target mass within the limit of capacity of the coiler furnaces and downstream equipment, and another, typically smaller, residual segment. The residual segment is disposed of, optionally first milled to end-product thickness in the Steckel mill, and transferred to conventional downstream equipment. In the meantime, the target segment is held within a coiler furnace. The target segment is subsequently milled and finished to end-product thickness. The method improves the efficiency of production in a steel rolling mill.

Plant capacity of optimizing method for use with Steckel mill

The in-line combination of a reversing rolling mill (Steckel mill) and its coiler furnaces with accelerated controlled cooling apparatus immediately downstream thereof and associated method permits steel to be sequentially reversingly rolled to achieve an overall reduction of at least about 3:1, imparted by a first reduction while the steel is kept at a temperature above the T.sub.nr by the coiler furnaces so as to preserve an optimum opportunity for controlled recrystallization of the steel after each rolling pass, and a second reduction while the temperature of the steel drops from about the T.sub.nr to about the Ar.sub.3. The second reduction is preferably of the order of 2:1 as a result of which the steel reaches a final plate thickness. The steel product then passes through the accelerated controlled cooling apparatus, preferably applying laminar flow cooling at least to the upper surface of the steel passing therethrough so as to reduce the temperature of the steel from about the Ar.sub.3 to a temperature at least about 250 C. to about 300 C. or more below the Ar.sub.3 at a cooling rate of at about 12 C. to about 20 C. and preferably about 15 C. per second, thereby to achieve a preferred fine-grained predominantly bainite structure affording enhanced strength and toughness in the final steel product.

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Aurora, IL, United States of America

Jonathan Dorricott