基板表面锈蚀对合金化热镀锌镀层的影响

Influence of substrate surface rust on hot-dip galvannealed coating

利用表面轻微锈蚀的Nb Ti-IF钢基板,在IWATANI热镀锌模拟器上进行了合金化热镀锌模拟,研究了基板表面锈蚀经还原退火后的表面状态,以及对最终合金化热镀锌镀层的影响。研究发现,在N2+5%H2的气氛中退火后,锈蚀被还原成有孔隙的细晶粒还原铁,在合金化过程中这些位置锌铁扩散快,形成的镀层比周围正常位置略厚、表面较平,最终在合金化镀层表面表现为白色斑迹。

Nb Ti-IF steel with slight surface rust was used in hot-dip galvannealing experiments which were carried out in IWATANI hot dip process simulator（ DHPS）. The influence of substrate surface rust on annealed sheet and galvannealed coating were studied. The rust on the substrate turned into fine and porous reduced iron after being continuous annealed in the atmosphere of N2＋ 5% H2.Due to the faster diffusion rate between the liquid zinc and iron at the rust areas during the galvannealing process,a thicker and flatter coating was formed,causing a white streaky mark defect.