Conseil national de recherches du Canada. Automobile et les transports de surface
flow composition and temperature; galvanizing operations; numerical modeling; validation
Worldwide demand for galvanized steel products continues to grow for the assembly of automobile structures that are lighter and more resistant to impact, as well as for applications in the construction and domestic appliance industries. The technical challenges faced by these producers are the ability to coat a variety of low cost, high strength steels in developing a product with minimal surface defects, and reduced consumption of zinc and energy. The performance of the coating process depends on a thorough understanding of the reactions at the steel surface, the bath chemistry, the temperature variation in the bath, and the fluid dynamics of the coating operation. Operational parameters such as line speed, bath configuration, and immersed hardware all contribute to the variability of the process. Numerical simulations of this process have determined the spatial distribution of temperature and composition of the critical constituents in the zinc bath in transient turbulent flow conditions. This simulation is able to identify the rate of formation and the location of the intermetallic dross particles (dross) within the bath. The generation of dross at the surface of the bath is also simulated experimentally using a mixing system with variable agitation and with air or nitrogen gas streams. Industrial tests carried out to continuously monitor the variation of the temperature and the Al and Fe composition are able to confirm the variations determined by the numerical simulations, validating the use of numerical simulation as an important means of analyzing a complex metallurgical process.