The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 22, 1978
Filed:
May. 06, 1976
Hans Paulitsch, Salzgitter-Lebenstedt, DE;
Alfred Babilon, Salzgitter-Lebenstedt, DE;
Gerhard Kiefer, Salzgitter-Lebenstedt, DE;
Kurt Koerfer, Salzgitter-Lebenstedt, DE;
Constantin Vlad, Wolfenbuttel, DE;
Ullrich Koch, Salzgitter-Lebenstedt, DE;
Stahlwerke Peine-Salzgitter A.G., Peine, Hann., DE;
Abstract
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.