高温灼烧导致的锌铝镁镀层裂纹缺陷分析及其防护措施

Crack Defects Analysis and Countermeasures of Zn-Al-Mg Coated Steel Caused by HighTemperature Burning Treatment

采用扫描电镜(SEM)观察裂纹区域的微观形貌,并利用EDS能谱测试其表面元素信息,同时分析了裂纹产生的原因。测试了高温灼烧处理前后镀锌铝镁板的极化曲线,并且测试了其中性盐雾试验。结果表明,高温灼烧后,镀锌铝镁板自腐蚀电位负,自腐蚀电流大;中性盐雾试验中相同时间内,高温灼烧后的镀锌铝镁板出现红锈量大于高温灼烧前的情形,说明高温灼烧处理对镀锌铝镁板镀层存在一定的破坏作用,降低其耐蚀性。另外,探讨了裂纹缺陷的防护措施,指出采取包覆湿布的方式对镀锌铝镁板进行防护,可以有效解决裂纹缺陷问题。

In this article,the causes of dendritic cracks on the surface of Zn-Al-Mg coated steel caused by high temperature burning treatment and their influence on its corrosion resistance were analyzed.The protective measures against crack defects were discussed.Micromorphology of the crack area was observed by scanning electron microscopy(SEM)and its surface element information was tested by the EDS and the causes of cracks were analyzed.The polarization curves and neutral salt spray tests of the galvanized aluminum magnesium plate before and after high temperature burning treatment were tested.The results showed that the self-corrosion potential of Zn-Al-Mg coated steel after high temperature burning treatment was more negative than that of the coated steel before high temperature burning treatment,and the self-corrosion current was larger.In addition,the neutral salt spray test showed that the amount of red rust in the Zn-Al-Mg coated steel after high temperature burning treatment was greater than that of the coated steel before high temperature burning treatment at the same salt spray treatment time,showing that the high temperature burning treatment had destructive effects on the coating of Zn-Al-Mg coated steel,such as reduction of its corrosion resistance.It was also revealed that the galvanized aluminum-magnesium sheet could effectively solve the occurrence of crack defects by covering it with a damp cloth.