08钢板制成的方管在电镀锌后,库存半个月左右发现其表面出现大量白斑,白斑数量随时间延长而增多.利用光学显微镜、扫描电子显微镜、能谱分析仪等分析手段对该白斑进行了理化分析,结果表明该方管由于镀锌前酸洗过度,钢板表面产生严重晶间腐蚀和晶粒脱落,导致镀锌过程中锌层愈合不良,锌层不连续.腐蚀产物主要为ZnO,呈白色绒毛状结晶物聚集在表面微孔区域.

White spots were discovered on square tube made of 08 steel plate after zinc-plated and then stored for about half a month.The number of white spots increased with time.Analysis methods such as OM,SEM and EDS were used to analyze the white spots.The results showed that the process of acid pickling was too heavy,so the surface of the steel plate ethibited serious intergranular corrosion and grains were peeled off.The poor uniformity of zinc-plating could not prevent corrosion completely,with the time increasing the chloride remained at joint gaps of grains could attack the zinc-plating too.