Yoichi Tobiyama1, Masahiko Tada1, Sakae Fujita1, Shigenari Hayashi2 and Masao Takeyama2
1Steel Research Laboratory, JFE Steel Corporation, Fukuyama 721-8501
The effect of oxidation accelerated by ammonium sulfate prior to annealing on galvannealing time of Si-bearing galvanized steel has been investigated to develop a new process for manufacturing Si-bearing galvannealed steel.
Oxidation accelerated by ammonium sulfate prior to annealing was effective to shorten the galvannealing time of the steel. The steel treated with ammonium sulfate showed the same galvannealing time as mild steel under the conventional oxidation condition.
This is probably due to not only the suppression of the formation of external oxides, which suppressed the Fe/Zn reaction during galvannealing but also the penetration of zinc into the grain boundaries and the reduced iron layer/the steel interface during galvanizing.
silicon, manganese, steel, oxidation, galvanizing, galvannealing, iron oxide, ammonium sulfate, surface segregation, external oxide
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