热基镀锌产品表面质量优化研究

发布时间：2018-03-16 17:42

本文选题：热基镀锌　切入点：锌层　出处：《华北理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文采用OM、SEM、EDS等检测分析手段,研究了唐钢热基热镀锌产品形成凹坑、黑斑、脱锌、钝化等缺陷的原因,提出了解决这些缺陷的措施,通过优化热基镀锌生产线的生产工艺,获得了涂镀性能良好的热基热镀锌产品,满足了高端用户的要求。得出的主要结论如下:凹坑缺陷形状极为规则,不具有周期性并且间歇性出现在镀层表面上,而且形状也极为相似,主要是由于机械划伤或是枝晶结晶速度以及形成的时间不同造成的。黑斑的直径大约400μm,缺陷处的枝晶组织有被摩擦或压扁的痕迹,缺陷部分比正常部分凸起高,使其压下量大于周围位置,从而产生了黑斑缺陷。亮斑的高度与周围稍有差别,比周围稍高,但与试样镀层的黑斑缺陷相比,又低于形成黑斑缺陷的凸起高度,形成亮斑的原因可能是锌液中形成的某种铝或锌的氧化物。优化了连续热镀锌生产工艺,包括降低带钢入锌锅温度,适当降低并控制锌液温度稳定性,降低锌液中Fe含量,增加带钢镀后冷却速率等。优化后的锌层中合金层明显减薄,锌层与基体结合处C、O含量明显减少,Al抑制层愈靠近锌层,限制了Fe向锌层扩散,显著提高了锌层的粘附性,显著降低了各类缺陷的产生。通过研究改良森吉米尔法炉内氛围及还原氧化的影响,优化了带钢温度梯度以及NOF炉内空气过剩系数等相关联参数,并充分利用通入高氢给炉内的方法,成功解决了氧化还原和锌层粘附性差的难题。
[Abstract]:In this paper, the causes of the defects such as pits, black spots, dezincification and passivation in hot base galvanizing products of Tangshan Iron and Steel Co., Ltd are studied by means of OMZEMs and EDS. The measures to solve these defects are put forward, and the production process of hot base galvanizing production line is optimized. The hot base hot-dip galvanizing product with good coating performance is obtained, which meets the requirements of high-end users. The main conclusions are as follows: the shape of pit defects is very regular, does not have periodicity and appears intermittently on the surface of the coating. And the shape is very similar, mainly due to mechanical scratches or different rates of dendritic crystallization and the time of formation. The diameter of black spots is about 400 渭 m, and the dendritic structure at the defects shows signs of being rubbed or flattened. The defect part is higher than the normal part, so that the reduction is larger than the surrounding position, which results in the black spot defect. The height of the bright spot is slightly different from the surrounding, slightly higher than the surrounding, but compared with the black spot defect of the sample coating, The cause of the bright spot may be some kind of aluminum or zinc oxide formed in the zinc solution. The continuous hot dip galvanizing process has been optimized, including lowering the temperature of the strip steel into the zinc pot, Decreasing and controlling the temperature stability of zinc solution, decreasing Fe content in zinc solution, increasing cooling rate of strip after plating, etc. The alloy layer in the optimized zinc layer is obviously thinned, and the content of Con O in the zinc layer at the interface between zinc layer and substrate is obviously reduced, and the inhibition layer of Al is closer to the zinc layer. The diffusion of Fe to zinc layer was limited, the adhesion of zinc layer was improved significantly, and the production of various defects was significantly reduced. The effect of modified Zenjimir process on the atmosphere and reduction and oxidation of zinc layer was studied. The temperature gradient of strip steel and the air excess coefficient in NOF furnace were optimized and the problems of redox and poor adhesion of zinc layer were solved by fully utilizing the method of high hydrogen feed furnace.
【学位授予单位】：华北理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG174.4

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