METHOD OF ANNEALING STAINLESS STEELS AND REMOVING SCALE FROM THEIR SURFACES

• Main Authors: KIM YEONG-U, ZAREMSKI DONALD R, HERTZLER CAROL S
• Format: Patent
• Language: English
• Published: 31.08.2000
• Edition: 7
• Subjects: APPARATUS THEREFOR; CHEMICAL SURFACE TREATMENT; CHEMISTRY; CLEANING OR DEGREASING OF METALLIC MATERIAL BY CHEMICALMETHODS OTHER THAN ELECTROLYSIS; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROMOBJECTS

A method for processing stainless steel strip or sheet provides for cleaning the surface of the stainless steel with a solution selected from the group consisting of water and alkaline-based and acid-based compounds to reduce oxide scale formation and to provide more uniform oxide scale during subsequent annealing by transverse-flux induction heating up to an annealing temperature of about 2300 degrees Fahrenheit and then electrolytically descaling by immersing in an aqueous solution electrolyte of one neutral salt, preferably, sodium sulfate maintained at a temperature in excess of 150 degrees Fahrenheit and with the use of low current density of 0.1 to 1.0 amperes per square inch to descale the steel substantially entirely, and thereafter applying a water rinse combined with wet wiping to the electrolytically-descaled stainless steel.