GALVANIZED STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME

• Main Authors: HOSHINO KATSUYA, NAGOSHI MASAYASU, HANADA KAZUTOSHI, TAIRA SHOICHIRO
• Format: Patent
• Language: English; Korean
• Published: 21.10.2016
• Subjects: 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; ELECTROFORMING; ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; METALLURGY; PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTIONOF COATINGS; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION

프레스 성형시의 슬라이딩 저항이 작고, 또한, 온도가 낮고, 라인 길이가 짧은 과혹한 알칼리 탈지 조건에 있어서도, 우수한 탈지성을 갖고, 형성한 산화물층의 용해를 억제하고, 또한, 세정 처리에 의한 얼룩의 발생을 억제 가능한 아연계 도금 강판의 제조 방법을 제공한다. 아연계 도금 강판에 황산 이온을 함유하는 산성 용액에 접촉시킨 후, 1∼60초간 유지하고, 그 후 물세정을 행하는 산화물층 형성 공정과, 상기 산화물층 형성 공정에서 형성된 산화물층의 표면을, 알칼리성 수용액에 접촉시킨 상태에서 0.5초 이상 유지하고, 그 후, 물세정, 건조를 행하는 중화 처리 공정을 구비하고, 상기 알칼리성 수용액은, P 이온을 0.01g/L 이상, 탄산 이온을 0.1g/L 이상 함유한다. Provided is a method for producing a galvanized steel sheet that exhibits a low sliding resistance during press forming, exhibits excellent degreasability even under stringent alkali degreasing conditions that involve a low temperature and a short line length, suppresses dissolution of the oxide layer formed, and is capable of suppressing occurrence of unevenness due to a washing treatment. The method includes an oxide layer forming step of bringing a galvanized steel sheet into contact with an acidic solution containing sulfate ions, then holding the galvanized steel sheet in contact for 1 to 60 seconds, and then washing the galvanized steel sheet with water; and a neutralization treatment step of holding a surface of an oxide layer, which has been formed in the oxide layer forming step, in contact with an alkaline aqueous solution for 0.5 seconds or longer, and then performing washing with water and drying. The alkaline aqueous solution contains P ions at a P concentration of 0.01 g/L or more and carbonate ions at a carbonate ion concentration of 0.1 g/L or more.