Control of the growth of zinc-iron phases in the hot-dip galvanizing process
Control of the growth of zinc-iron phases in the hot-dip galvanizing process
复制标题
DOI：
10.1016/s0257-8972(99)00404-1
复制
发表时间：
1999-12-01
影响因子：
5.4
通讯作者：
Di Sarli, AR
中科院分区：
文献类型：
--
作者：
Culcasi, JD;Seré, PR;Di Sarli, AR
在热浸镀锌过程中，锌-铁相可能在钢基体/锌涂层界面处形成。这些相是硬的和脆的，并且使得材料不适合于成形过程。锌-铁相的生长可以通过向镀锌浴中添加0.18至0.30%的铝来控制，铝与铁反应以产生金属间化合物Fe 2Al 5的薄层。后者阻碍钢板和熔融锌之间的合金化，因此被称为抑制层，因为它抑制或延迟Fe-Zn相的形成。然而，该层是不稳定的，并且在较长的浸没时间下发现Fe-Zn相的局部生长（“爆发”）。这种“突出”现象取决于许多因素，如镀液和钢的化学成分，以及浸泡时间。这项工作的目的是研究浸泡时间和少量钛加入镀锌液对镀层特性的影响。因此，用具有不同化学组成的合金A和B对普通碳钢板进行镀锌。浸泡时间在1和120秒之间变化。通过扫描电子显微镜观察样品的横截面。分析表明，即使浸泡时间很短，用合金A镀锌的样品也会出现“突出”，而用合金B镀锌的样品即使浸泡时间较长也不会出现“突出”。还研究了Fe 2Al 5金属间化合物结构。观察到，对于相同的浸泡时间，用合金B镀锌的样品显示出比用合金A镀锌的样品更大的晶粒。然而，对于这两种合金，金属间化合物的发展是更长的浸泡时间。这些观察结果表明，少量的钛可以作为铁-铝反应的催化剂，允许更大的抑制层的发展和延迟Fe-Zn金属间化合物的生长。(C)1999年Elsevier Science S.A. All rights reserved.
Zinc-iron phases may develop at the steel substrate/zinc coating interface during the hot-dip galvanizing process. These phases are hard and brittle, and make the material unsuitable for the forming process. Growth of the zinc-iron phases could be controlled adding 0.18 to 0.30% of aluminium to the galvanizing bath, which reacts with iron to produce a thin layer of intermetallic Fe2Al5. The latter hinders alloying between the steel sheet and molten zinc, and is therefore referred to as the inhibition layer since it inhibits or retards the formation of Fe-Zn phases. Nevertheless, this layer is unstable and local growth of Fe-Zn phases ('out-burst') is found at longer immersion times. This 'out-burst' phenomenon depends on many factors, such as the chemical compositions of both the bath and the steel, and the immersion time.The aim of the work was to investigate the influence of both immersion time and a small addition of titanium to the galvanizing bath on coating characteristics. Thus, plain carbon steel sheets were galvanized with alloys A and B, which had different chemical compositions. The immersion time was varied between 1 and 120 s. Cross-sections of samples were observed by scanning electron microscopy. The analysis showed that, even for very short immersion times, samples galvanized with alloy A develop 'out-bursts' whereas those with alloy B do not, even for longer immersion times. The Fe2Al5 intermetallic structure was also investigated. It was observed that samples galvanized with alloy B showed, for the same immersion time, bigger grains than the ones galvanized with alloy A. However, for both alloys, the intermetallic development was greater for longer immersion time. Such observations suggest that a small amount of titanium could serve as a catalyst for the iron-aluminium reaction, allowing a greater development of the inhibition layer and delaying growth of the Fe-Zn intermetallic. (C) 1999 Elsevier Science S.A. All rights reserved.