PRODUCTION METHOD FOR HIGH-STRENGTH HOT-DIP GALVANIZED STEEL SHEETS AND PRODUCTION METHOD FOR HIGH-STRENGTH ALLOYED HOT-DIP GALVANIZED STEEL SHEETS

• Main Authors: SUZUKI YOSHITSUGU, NAGATAKI YASUNOBU, MIYATA MAI
• Format: Patent
• Language: English; Korean
• Published: 20.04.2016
• Subjects: ALLOYS; APPARATUS THEREFOR; 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; ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; FERROUS OR NON-FERROUS ALLOYS; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; METALLURGY; PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROMOBJECTS; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TREATMENT OF ALLOYS OR NON-FERROUS METALS

Cr을 함유하는 강판에 대해, 강판 표면에 형성되는 산화물이 원인이 되는 문제를 억제하고 도금 밀착성, 표면 외관이 우수한 고강도 용융 아연도금 강판을 제조하기 위한 제조 방법, 및 고강도 합금화 용융 아연도금 강판을 제조하기 위해 제조 방법을 제공한다.　특정의 성분 조성 강판을, 특정의 H농도, 특정의 노점 분위기 중, 특정의 온도에서 특정의 시간 유지하는 제 1 가열 공정과, 제 1 가열 공정 후의 강판을, 냉각하는 냉각 공정과 냉각 공정 후의 강판을 특정의 조건에서, 전해 처리하는 전해 처리 공정과 전해 처리 공정 후의 강판을, 특정의 H농도, 특정의 노점 분위기 중, 특정의 온도로 특정의 시간 유지하는 제 2 가열 공정과 제 2 가열 공정 후의 강판에, 용융 아연도금 처리를 가하는 도금 처리 공정을 구비하는 방법으로 고강도 용융 아연도금 강판을 제조한다. Problems caused by oxides formed on a surface of a steel sheet containing Cr are solved. There is provided a method for producing a high-strength hot-dip galvanized steel sheet having good adhesion of the coating and a good surface appearance and a method for producing a high-strength galvannealed steel sheet. A high-strength hot-dip galvanized steel sheet is produced by a method that includes a first heating step of holding a steel sheet at a specific temperature for a specific time in an atmosphere having a specific H 2 concentration and a specific dew point, the steel sheet having a specific composition, a cooling step of cooling the steel sheet after the first heating step, an electrolytic treatment step of subjecting the steel sheet after the cooling step to electrolytic treatment under specific conditions, a second heating step of holding the steel sheet after the electrolytic treatment step at a specific temperature for a specific time in an atmosphere having a specific H 2 concentration and a specific dew point, and a coating treatment step of subjecting the steel sheet after the second heating step to hot-dip galvanizing treatment.