关键词: DP080GA钢, 漏镀缺陷, 锰选择性氧化, 置换反应

Abstract: Causes of surface bare defects of alloyed galvanized DP980GA strip were analyzed by means of macro and micro morphology observation and composition analysis. The results show that a large number of manganese oxide and iron oxide particles are found inside the plating pit, and a small amount of alumina and chromium oxide are also found, which is due to the enrichment and selective oxidation of manganese on the surface of the steel strip in the continuous annealing furnace, and the aluminothermic replacement reaction in the zinc pot is incomplete, thus reducing the wettability of the strip surface and causing the bare defects. It is suggested that through moderately reducing the dew point temperature of the heating section in the continuous annealing furnace to reduce the manganese oxide film formed by selective oxidation on the surface and its thickness, and moderately increasing the Al content in the zinc pot to promote the aluminothermic replacement reaction, the manganese oxide on the surface of the strip can be fully replaced by alumina and sunk into the zinc pot, thereby the wettability of the strip surface can be improved and the problem of surface bare defects can be solved.

Key words: DP080GA steel, bare defect, selective oxidation of manganese, substitution