Galvannealed steel sheet and method for manufacturing the same

• Main Authors: TAIRA, SHOICHIRO, INAGAKI, JUNICHI, INAGAKI, TOMOKO, SUGIMOTO, YOSHIHARU, IMOKAWA, TORU
• Format: Patent
• Language: English
• Published: 11.09.2005
• Edition: 7
• 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

The present invention relates to a galvannealed steel sheet having an oxide layer of 10 nm or more thickness on the convex surface of coating flattened by temper rolling. The use of the galvannealed steel sheet causes little powdering and lowers the sliding resistance at press forming. Especially, it is more preferable when the areal ratio of the convex surface of coating flattened by temper rolling is 20-80%, that the coating consists of a single phase of delta1, or that the delta1 contains a zeta phase.