热浸镀工艺对低碳钢铝锌硅镀层表面形貌及组织的影响

Influence of hot dipping on surface morphology and microstructure of Al-Zn-Si coating on low carbon steel

利用CAG-III热浸镀锌模拟试验机对低碳钢DX51D基板进行一组不同浸镀温度及时间下的热浸镀铝锌硅试验。通过显微镜、扫描电镜及能谱仪等对试样表面形貌及组织进行分析。结果表明：该Al-Zn-Si镀层表面形貌为典型六边形树枝状,枝干为富Al的固溶体相,填充于枝间的为富Zn固溶体相,Si元素则弥散分布在整个镀层表面上。浸镀温度为580℃、浸镀时间为10 s时,镀层表面质量最佳,镀层截面厚度较为均匀,为50μm左右。Al-Zn-Si镀层外层为Al-Zn合金凝固形成的结晶层,其中连续灰色相为富铝相,富铝相中分散分布的白色块状相为富锌相,内层为由Al、Zn、Fe、Si元素组成的四元合金相。

A hot dipping Al-Zn-Si test of a low carbon steel DX51 D with different dipping temperatures and time was carried out by CAG-III hot dip galvanizing simulation machine. The surface morphology and microstructure of the coating were investigated by using of metallurgical,scanning electron microscope（ SEM） and energy spectrum analysis（ EDS）. The results show that the surface morphology of the coating is typical hexagon dendrite,which consists of Al-rich dendrite phase and inter-dendrite eutectic Zn-rich phase,and Si element disperses on the surface. When dipped at 580 ℃ for 10 s,the surface quality of the coating is the best,and the coating section thickness is more uniform,being about 50 μm. The outside layer of the coating is a solidified Al-Zn alloy layer composed of a continuous grey Al-rich phase with a dispersive Zn-rich phase,while the inner layer is composed of a Al-Zn-Fe-Si quaternary alloy phase.