METHOD OF COATING A FURNACE-HEATED,FERROUS METAL STRAND WITH A METALLIC COATING MEDIUM AND APPARATUS FOR CARRYING ON THE METHOD

摘要

After furnace heating, a continuous rolled ferrous metal product is hot dip metal coated by passing it through a protective hood, the outlet of which dips below the surface of the molten metal coating bath. A still atmos. of reducing gas is maintained within the hood at least near its outlet and reducing gas is introduced into the furnace outlet section in front of the hood, the rate of diffusion of the reducing gas from the furnace outlet section to the hood being limited to a rate no higher than that necessary to maintain a constant gas quantity and compsn. in the hood. The process is useful for hot dip coating ferrous metal strip, wire or rod with aluminium-zinc alloy and avoids the need for a hot reducing atmos., reduces the volume of reducing gas required, reduces the occurrence of defects such as coating-free pits and avoids the formation of zinc or other deposits in the hood.