Failure Analysis of the Sleeves and Bushings in Hot-dip Galvanizing

A serious problem was noticed in continuous hot-dip galvanizing,that is,the system was prone to move violently and the routine maintenance shutdowns were frequently required.Failure analysis of the sleeves and the bushings was done by using optical microscopy,SEM,X-ray diffraction analyzer.The failure reasons were discussed.The results indicated that the corrosion wear process of the sleeve included the corrosion of binding phase,surface fatigue wear,adhesive wear and abrasive wear,which made the sleeve dimensions decrease and the galvanizing system fail in the end.The failure modes of the bushing were the crack corrosion induced by molten zinc,adhesive wear and peeling-off of particles.