不同入锅温度和气氛下高Al-Mg含量的锌基镀层汽车用钢镀层形貌对比

Morphology of High Al-Mg-Zn Coated Auto Steel Hot Dipped by Different Diving Temperature and Atmosphere

摘要: 采用含有较高Al-Mg含量的锌液(7.2%Al~1.6%Mg-Zn)，改变钢板入锅温度、露点和H₂含量，研究该3种热镀工艺参数对汽车用深冲钢镀层质量和形貌的影响。结果表明，试验钢冷轧薄板在高Al含量的镀液中具有良好的浸润性，厚度均在10~20 µm左右。镀层由三种不同形貌组织的组成：亮白色Zn颗粒、粗大富Al相、细小密布富Mg相。随着热镀工艺的钢板，镀层形貌有明显的差异：入锅温度为460、475、490˚C时，镀层形貌变化不大；露点从−50增加到30˚C，粗大富Al相大大减少，亮白色Zn颗粒更为细小；H₂含量从5增加到15%时，粗大的富Al相破碎，贯穿整个视场的枝晶状组织消失。

Abstract: The effect of three hot dipping parameters on coating quality and morphology of deep drawing auto steel by high Al-Mg content zinc pot was studied, including diving temperature, dew point and H₂ content. The results display that, the cold rolled thin sheet has a good wettability in the high Al-Mg content zinc pot, with average coating thickness from 10 to 20 µm. The coating morphology consists of three phases: bright Zn particle, coarse Al rich phase and fine Mg rich phase. The coating morphology changes a lot with different dipping parameters: as diving temperatures increase from 460˚C to 490˚C, the morphology has little difference with each other; as dew points increase from −50˚C to 30˚C, the amount of coarse Al rich phase decreases significantly, and Zn particles became finer; as H₂ content increases from 5% to 15%, the coarse Al phase is broken and the dendrite structure disappear.