Wetting Characteristics of Low Carbon Rimmed Steel with Molten Zinc

Abstract

A low carbon rimmed steel heated for a short time in an H₂-N₂ gas was dipped into a molten zinc. The effects of the steel sheet factors, reduction heating conditions and the reducing gas conditions on the wetting characteristics were studied by use of a measuring instrument of gas reduction type meniscograph. A study was also made on the relation between the wettability of steel and the structure of the surface layer of it which was changed depending on these conditions.
The main results obtained are as follows:
1) If the surface layer is made hard by plastic deformation, an increased rate of wetting is caused.
2) The rougher the surface, the higher the equilibrium extent of the wetting force. The surface roughness being the same, the wetting force is lowered when the dew point of the atmospheric gas is raised.
3) The wetting rate sharply increases with the steel temperature just before dipping if it lies between 400°C and 640°C.
4) If the dew point of the gas is increased to the temperature higher than -30°C, the wettability, especially the wetting rate of the steel is deteriorated, which might be caused by Fe-oxide film formation.