冷轧镀锌退火炉内气氛研究

Research on the Atmosphere in the Annealing Furnace for Cold Rolled Galvanizing

连续热镀锌生产线的退火炉炉内气氛是由氮气和氢气组成的还原性保护气体组成,在镀锌线生产中起着保护带钢,防止带钢氧化,并还原带钢表面氧化物,增加镀锌浸润性的作用。炉内气氛的优劣是决定锌层粘附性的重要因素。重点介绍炉内各气氛成分的占比与检测,氮气含量、氢气含量、氧气含量、露点在加热炉内对带钢的作用以及对带钢质量的影响,合理的气氛占比达到对带钢的保护和还原杂质的平衡;分析炉内气氛变差的原因,结合生产实践介绍了退火炉气密性的检查、处理方法以及预防措施;根据加热炉各工艺段工艺要求不同采取不同的气氛配比,尤其是露点的控制,加热段的露点能从一定程度上反映保护气体的还原能力,而炉箅子段露点的控制的作用主要是抑制锌灰的产生,锌灰附着在带钢表面会形成锌斑、亮点等质量缺陷,严重影响带钢表面质量,降低板材质量等级。高端的汽车外板对于表面质量要求非常严苛,所以优良的炉内气氛是生产高端汽车板材重要保障。

The atmosphere inside the annealing furnace of a continuous hot continuous galvanizing line is composed of a reducing protective gas composed of nitrogen and hydrogen.It plays a role in protecting the strip steel,preventing oxidation,and reducing the surface oxide of the strip steel to increase the wettability of the galvanizing process.The quality of the atmosphere inside the furnace is an important factor determining the adhesion of the zinc layer.This article focuses on the proportion and detection of various atmosphere components in the furnace,as well as the effects of nitrogen content,hydrogen content,oxygen content,and dew point on the strip steel in the heating furnace and their impact on the quality of the strip steel.A reasonable atmosphere proportion can achieve a balance between protecting the strip steel and reducing impurities;Analyze the reasons for the deterioration of the atmosphere inside the furnace,and introduce the inspection,treatment methods,and preventive measures for the airtightness of the annealing furnace based on production practice;According to the different process requirements of each process section of the heating furnace,different atmosphere ratios are adopted,especially the control of dew point.The dew point of the heating section can reflect the reducing ability of the protective gas to a certain extent,while the control of dew point in the grate section mainly suppresses the production of zinc ash.Zinc ash adhering to the surface of the strip steel will form quality defects such as zinc spots and bright spots,seriously affecting the surface quality of the strip steel and reducing the quality level of the plate.High end car exterior panels have very strict requirements for surface quality,so a good furnace atmosphere is an important guarantee for producing high-end car panels.