钴对含硅钢镀锌层的组织和生长动力学的影响

利用扫描电镜及波谱,研究锌浴中的钴对Q235和Q345钢热浸镀锌层组织及其生长动力学的影响.结果表明:锌浴中含0.075%(质量分数)钴时,能完全抑制Q235镀层组织发生硅反应性;而对于Q345,则需要在锌浴中加入0.3%钴才能部分抑制硅反应性;在锌浴中加入少量的钴后,镀层组织中疏松ζ层转变成与液相直接接触的富钴ζ相和由消耗δ相生成的致密ζ相;致密的ζ相层阻止液相和δ相的直接接触;富钴ζ相可容纳大约0.25% Si,避免在固-液界面产生硅的富集,液相通道消失,从而抑制含硅钢热浸镀锌过程中硅反应性的产生.

Effect of Co on microstructures and growth kinetics of galvanizing coating on Si-containing steel

The effect of Co in Zn bath on the microstructures and growth kinetics of hot-dip galvanized coating on Q235 and Q345 steels were investigated by scanning electron microscopy and wave dispersive spectroscopy (SEM-WDS). The results show that adding 0.075% (mass fraction) Co into the Zn bath can completely inhibit the silicon reactivity in the galvanized coating on the Q235 steel. But for the Q345 steel, to inhibit the silicon reactivity, 0.3% Co should be added into the Zn bath. The loose ζ layer is transformed into the Co-rich ζ layer contacted directly with the liquid phase and the compact ζ layer formed by consuming δ phase after adding a small amount of Co into the Zn bath. The compact ζ layer can prevent the direct contact between the liquid phase and the δ phase. The solubility of Si in the Co-rich ζ phase, which is about 0.25%, can avoid the enrichment of silicon at the boundary between the coating and the liquid, and the liquid channel vanishes. This restrains the silicon reactivity during the hot-dip galvanizing of the Si-containing steel.