Krupp Stahl Aktiengesellschaft

Mannesmann Aktiengesellschaft

Jurgen Flugge

Wilhelm Heller

Michael Haentjes

Franz G Pempera

Gerhard Ratz

Reinhard Schweitzer

Lutz Weber

Horst Edel

Rainer Kilb

Andreas Jaenichen

A process and apparatus for the continuous treatment of annealed and non-annealed hot strip of stainless steel. First, the hot strip is stretched, bent and straightened to break a scale which has grown on the hot strip. Then, a electrolytic pickling is performed in an electrolyte with multiple alternating anodically-connected and cathodically-connected strip polarization. Directly following thereafter, pickling once again takes place in the electrolyte with multiple anodically-connected electrodes arranged directly behind one another and corresponding cathodic strip polarization, followed by anodic strip polarization produced by means of a cathodically-connected electrode. To further remove any scale remaining on the surface of the hot strip, the hot strip is subject to high-pressure fluid spraying or brush aggregates. Renewed electrolytic pickling in performed with at least one electrolyte with multiple exclusively cathodically-connected electrodes and anodic strip polarization. Finally, post-treatments are performed such as washing, brushing, post-washing and drying of the strip surface.

Process and apparatus for producing strip products from stainless steel

The present invention relates to a method for thermal treatment of pearlitic rail steel. For increasing strength and wear resistance steels with the claimed composition are produced with a fine lamellar pearlite structure by heat treatment. During the first cycle the rail head portion is heated in a sufficient depth of up to 50 mm by means of a burner or an inductive system to an austenitization temperature of about 950.degree. to 1050.degree. C. Thereafter the heated head portion is cooled by means of compressed air in such a way that in a first step by blowing a large amount of air the temperature of the rail head portion is cooled within 10 to 20 s to 650.degree. to 600.degree. C. before the area of the pearlitic transformation. In a second step with throttled blowing compared to the first step in the area of the pearlitic transformation the rail head portion is cooled within 2 to 4 minutes to about 400.degree. C. until finishing the pearlitic transformation. Then the rail head portion is again heated for 4 to 6 minutes to a temperature of about 600.degree. to 650.degree. C. and then rapidly cooled by means of water or other appropriate quenching media to a temperature of less than 100.degree. C.

Method for thermal treatment of pearlitic rail steels

The present invention relates to a process for reducing internal stresses of roller straightened rails. After the straightening operation the rail web portion is heated for a short time to temperatures ranging between 200.degree.-700.degree. C., preferably between 350.degree.-500.degree. C., and after reaching the desired temperatures the rail is cooled by air to room temperature. For the purpose of heating the rail is continuously conveyed in front of the heating apparatus. The inventive process permits to reduce internal stresses in the rail head and base portions to a value of less than 50 N/mm.sup.2 thus ensuring increased rupture strength of the rail.

Method for reducing internal stresses of roller straightened rails

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Duisburg, Germany

Jurgen Flugge