Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403


공학

한국표면공학회지 (48권1호 27-32)

Behavior of the Surface Precipitation of Manganese Oxides during Hot-dip Galvanizing

용융아연 도금욕에서 망간 산화물의 표면석출 거동

이호종;김명수;
Lee, Ho Jong;Kim, Myung Soo;

순천대학교 신소재공학과;포항제철 기술연구원;
Department of Advanced Materials Engineering, Sunchon National University;POSCO Technical Research Laboratories;

DOI : 10.5695/JKISE.2015.48.1.027

Abstract

Advanced high strength steels undergo recrystallization annealing in reducing gas atmosphere before galvanizing to improve mechanical properties. The selective oxidations of elements such as Mn, Si, Cr and Al during annealing decrease wettability of liquid zinc, resulting in bare spots and other defects. In this work, Fe-3wt%Mn steel sheet was annealed at $780^{circ}C$ for 1200 sec. in 5% $H_2-N_2$ atmosphere and then dipped into zinc bath held at $460^{circ}C$, which contained 0.2wt% dissolved Al. MnO crystallines in the average size of 200 nm were formed on the surface after annealing. It is estimated that MnO has been detached into bath with the formation and growth of inhibition layer with longer immersion time during galvanizing. No evidence of aluminothermic reduction of MnO has been found in this study.

Keywords

Annealing;Manganese oxide;Galvanizing;