冷却工艺对镀铝锌钢板锌花尺寸与组构的影响

为提升厚规格镀铝锌板的表面质量、控制锌花尺寸、增强镀层观赏性,使用热浸镀模拟机组在厚规格钢板基体上制备了不同镀后冷却工艺的铝锌镀层(55.0Al-43.4Zn-1.6Si),使用扫描电子显微镜(SEM)及能谱仪(EDS)观察了镀层表面和截面的微观形貌及元素分布,探讨了镀后冷却工艺对铝锌镀层锌花尺寸、表面及截面形貌与结构的影响。结果表明:对于厚规格镀铝锌钢板,在600-380℃温度区间增大镀后冷却速率可降低锌花尺寸、增加枝晶取向的多样性,从而增强锌花立体感;同时可细化镀层组织、减小镀层表面二次枝晶间距,并降低金属间化合物层厚度。冷却过程中,600-520℃温度区间是镀层组织形核长大的关键阶段,因此在该温度段增大冷却速率可较为显著地减小锌花尺寸、细化镀层组织、提升镀层观赏性。

Effects of Cooling Process on Spangle Size and Microstructure of Al-Zn Alloy Coated Steel

Several Al-Zn alloy coating layers with different cooling processes were prepared on thick steel sheet substrates by hot-dip simulation unit. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) were used to investigate the microstructure and element distribution of coating layers. Results showed that increasing the cooling rate at 600-380℃ could reduce the spangle size and enhance the sense of volume by increasing the orientation of dendrites. Moreover, increasing the cooling rate could decrease the secondary dendrite arm spacing by refining the microstructure and reduce the thickness of intermetallic compound layer. During the cooling procedure, 600-520℃ was an important temperature interval for nucleation and growth. Therefore, enhance the cooling rate in 600-520℃ interval could prominently reduce spangle size, refine microstructure and improve the ornamental value.