研究論文
Si, Mn, P添加高強度溶融亜鉛めっき鋼板の合金化特性および耐パウダリング性に及ぼす内部酸化の影響
2007 年 58 巻 3 号 p. 183
詳細
2007 年 58 巻 3 号 p. 183
During the heat treatment of 0.3mass%Si-1mass%Mn-0.07mass%P ultra low carbon hot-rolled steel, readily oxidizable elements such as Si, Mn and P were internally oxidized and a depletion layer of these elements was formed at the steel surface region. The amounts of Si and Mn selective surface oxidation of the cold-rolled steel were remarkably suppressed after recrystallization annealing.
By this heat treatment of the hot-rolled steel, the galvannealing rate of the galvanized steel was accelerated to a rate equivalent to that of mild steel. As a result, the galvannealing temperature of the galvannealed steel could be lowered and the anti-powdering properties of the galvannealed steel were remarkably improved.
The reasons for acceleration of the galvannealing behavior and the improvement of the anti-powdering properties, were considered as follows :
1) The amount of Si and Mn selective surface oxidation, which acted as a barrier for the Fe-Zn galvannealing reaction, was suppressed.
2) The amount of solute P, which delays the Fe-Zn galvannealing reaction, was reduced.
3) The reduction of galvannealing temperature brings about the suppression of the Γ and Γ1 phases formed at the higher temperature, those unfavorable for anti-powdering properties.
