Effects of Oxidation-reduction Heating Conditions on Wetting Characteristics of Silicon Containing Steel with Molten Zinc

Abstract

Effects of Si content in steel and the condition of partially- or non-oxidizing treatment followed by reduction treatment on dynamic wetting characteristics of Si-containing steels immersed in a molten zinc bath were studied by means of a partially- or non-oxidizing furnace simulator and a measureing instrument of gas reduction type meniscograph.
1) Steels containing 0.83% Si exhibited a good wettability when they were oxidized partially at an air/fuel ratio of 1.05 or more, which formed an oxide film of visible thickness and then reduced for 30 to 40s at 700°C.
2) The zinc wettability of Si-containing steels well corresponded to the degree of formation of Fe containing oxygen, namely Fe(O) and also the degree of Si enrichment at the steel surface layer which was composed of (FeO)₂ SiO₂.
3) The surface topography of steels changed in accordance with the air/fuel ratio during the partially-oxidizing treatment, Si content in steels and reduction treatment conditions. The rougher and more porous the surface morphology, the greater the initial wetting rate of the steels.