PRODUCTION OF GALVANNEALED STEEL SHEET

• Main Authors: NUMAKURA YUKIO, SUZUKI SHINICHI
• Format: Patent
• Language: English
• Published: 29.01.1992
• Subjects: CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; METALLURGY; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION

PURPOSE:To level the alloying velocities of various steel sheets dissimilar in alloying reaction velocity by previously applying Fe-C composite plating to the surface of a steel sheet, applying hot-dip galvanizing to the above, and then carrying out alloying treatment by heating. CONSTITUTION:A steel sheet is introduced into a bath in which, e.g., polyethylene glycol is added by 0.01-20g/l to an aqueous solution of ferrous sulfate and/or ferrous chloride, and electrolytic treatment of about 30-300A/dm current density and about 0.1-30sec time is performed by using the steel sheet as a cathode, by which polyethylene glycol, etc., as C material are formed into eutectoid in the Fe plating layer by about 0.01-1% expressed in terms of C. Subsequently, the steel sheet is subjected to temp. rise up to about 500-700 deg.C in a nonoxidizing furnace and held at about 500-800 deg.C in a reducing furnace, and then, an Fe-C composite plating layer of about 0.5-10g/m thickness is formed. By subjecting this plated steel sheet to hot-dip galvanizing and then to alloying treatment by heating, alloying treatment can be performed while practically obviating the necessity of modifying alloying treatment conditions (temp., time), depending on the type of steel.