Research and Control Strategy of Pitting Defect in Hot Base Galvanizing
In view of the"pitting"defect on the surface of hot-base zinc-free galvanized sheet,the morphology of the defects was studied by SEM and LSCM,and the effects of induction heating atmosphere on the defects were studied.The results show the"pitting"defect on galvanized surface of hot substrate is caused by the interaction of pit in substrate and pinhole defect in coating,which results in the non-uniform flow of zinc solution after the steel plate is discharged from the zinc pot.The main reason of pinhole defect is the abnormal dew point value of atmosphere in induction heating furnace.By controlling the drying degree of the surface of steel strip before entering the heating furnace,the dew point value in the furnace is stabilized below-35 ℃."Pockmarks"defects have been significantly improved.
hot base galvanized sheepitting defectatmosphere in the furnacedew point value
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