Impact of Copper, Tin and Titanium Addition on Bending-Induced Damage of Intermetallic Phases in Hot Dip Galvanizing

Abstract

Hot dip galvanizing is among the cheapest methods for protecting ferrous alloys against corrosion. The success is due to both the low cost of the process and the high degree of protection in many corrosive environments, where the coatings serve as sacrificial protection. The purpose of this analysis is to study the mechanical characteristics of steel plates, that have been hot dip coated with five different zinc alloy molten bath for different time periods. The mechanical tests performed is a non-standardized four-point bending test considering three distinct bending angles. Results are examined in terms of both mechanical behaviour and coating phase damage. The development of intermetallic phases and their damage are both influenced by the chemical compositions of the zinc bath, demonstrating that fractures arise mostly at the substrate-coating interface. All the coatings showed the arising of micro-cracks except for the Aluminium, which demonstrated its ductility. In addition, Zn-Ti coatings showed the arising of a new compact phase rich in iron, characterized by a great hardness. More research is needed to explore the aluminium impact on the zinc bath, the lack of tiny fractures in the phase, and the lesser thickness compared to the other coatings tested.