Stahlwerke Peine-salzgitter Ag

Constantin M Vlad

Hans Paulitsch

Gerhard Kiefer

Alfred Babilon

Kurt Koerfer

Ullrich Koch

Klaus Freier

Klaus Hulka

An improved method for the manufacture of hot strips or heavy plates from a denitrated steel composed of 0.04 to 0.16% carbon, 1.25 to 1.90% manganese, 0.2 to 0.55% silicon, 0.004 to 0.020% phosphorus, 0.002 to 0.015% sulfur, 0.02 to 0.08% aluminum, 0.02 to 0.08% niobium, the remainder iron and possibly contaminants, including the steps of having the hot strips or plates leaving the last finishing stand of rolls at a temperature of 750.degree. C. to 820.degree. C., cooling the hot strips or plates to an intermediates temperature of 450.degree. C. to 500.degree. C. at a cooling rate of 2.degree. to 10.degree. C./s and then slowly cooling the hot strips or plates in air to room temperature in a coil or in a pile.

Hot strips or heavy plates from a denitrated steel and method for their

A cooling arrangement, especially but not exclusively suited for cooling rolled stock such as wires and bars, has two end members provided with axially aligned passages through which a workpiece can travel. The end members are connected by an annularly arranged series of bars between which spaces are left free so that cooling fluid admitted into contact with the workpiece can rapidly flow off again. The space surrounded by the bars converges in the direction of travel of the workpiece. Upstream of one end member is provided a fluid admitting element formed with a workpiece guide passage which is divergent-convergent as considered in the travel direction of the workpiece. A fluid inlet arrangement has an inner wall bounding the passage and provided with circumferentially spaced slot-shaped openings which communicate with the divergent part and extend toward the convergent part, and an outer wall surrounding the inner wall and bounding with the same an annular fluid chamber from which the slot-shaped openings receive fluid.

Cooling arrangement

A steel wire after coming from the mill is brought to a temperature between 850.degree. and 910.degree. C. This is followed by multi-stage water-cooling of the wire in such a manner that the surface of the wire is cooled to below the martensite start temperature while austenite is retained in the core of the wire. The heat retained in the core of the wire serves to partially temper the martensite formed at the surface of the wire. The wire is coiled while the temperature remains substantially constant so that the retained austenite in the core of the wire undergoes an isothermal transformation to fine pearlite. The heat of transformation serves to complete tempering of the martensite. After coiling, the wire is air-cooled to room temperature. The final wire exhibits a structure consisting of an outer layer of tempered martensite and a core of fine pearlite. This structure imparts excellent cold-working characteristics to the wire.

Method of making a steel wire adapted for cold drawing

A steel wire is rolled while in the austenitic range. Thereafter, the wire is cooled to a temperature between 850.degree. and 910.degree. C. This is followed by multi-stage water-cooling of the wire in such a manner that the surface of the wire is cooled to below the martensite start temperature while austenite is retained in the core of the wire. The latter cooling step brings the temperature of the surface of the wire to below the martensite start temperature in approximately 0.2 seconds. The heat retained in the core of the wire serves to partially temper the martensite formed at the surface of the wire. The wire is then coiled while the temperature remains substantially constant so that the retained austenite in the core of the wire undergoes an isothermal transformation to fine pearlite. The heat of transformation serves to complete tempering of the martensite. After coiling, the wire is air-cooled to room temperature and exhibits a structure consisting of an outer layer of fully tempered martensite and a core of fine pearlite. This structure imparts excellent cold-working characteristics to the wire since both the tempered martensite and the fine pearlite may be readily cold-drawn and, in addition, the tempered martensite at the surface of the wire possesses great strength which enables the stresses generated during cold-working to be transmitted along the wire. The reduction of area of the wire during cold-working may amount to 85 percent and more.

Steel wire

Alloy steel sheeting for electrical purposes such as the cores of transformers, is made with isotropic magnetic properties by a method in which steel containing, by weight, up to 0.1% carbon, from 0.15 to 0.35% manganese, from 0.3 to 2.4% aluminium up to 0.25% copper, up to 0.5% sulphur, up to 0.2% phosphorus, up to 2.0% silicon and the balance iron except for impurities is hot rolled at a temperature of from 820.degree. to 1080.degree.C to cause at least 5% of it to have a crystal orientation {100} &lt;hkl&gt;. After this the sheet is cold-rolled with a reduction in cross-section of from 50% to 85% and then it is recrystallization-annealed at a temperature of from 820.degree. to 1200.degree.C. Preferably the cold-rolling is carried out in two stages and the sheet is annealed for from 10 to 30 minutes at a temperature of from 550.degree. to 950.degree.C between the two stages.

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Nordassel, Germany

Constantin M Vlad