GALVANNEALED HEAT-TREATED STEEL MATERIAL AND PROCESS FOR PRODUCING THE SAME

• Main Authors: ISHII KAZUYA, SHIMADA NAOAKI, KOJIMA NOBUSATO, TOMIZAWA ATSUSHI, NAKAMURA TOYOMITSU, TOKI TAMOTSU, IMAI KAZUHITO
• Format: Patent
• Language: English; Korean
• Published: 24.07.2012
• 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

A heat treated galvannealed steel material having excellent post-painting corrosion resistance and a high strength which is suitable for use as an automotive part and a method for its manufacture are provided. A galvannealed steel material having a galvannealed coating on at least one side thereof is heat treated by heating at least a portion thereof to a temperature range in which hardening is possible. The coating remaining on the surface of at least a part of the portion which underwent heat treatment has a coating weight of at least 20 g/m 2 and at most 80 g/m 2 per side and an Fe content of at least 15% and at most 35%, an · phase is present in the coating, and the centerline average roughness Ra of the surface of the coating is at most 1.5 µm.