Influence of Joining Conditions on Residual Oxide in Joining with Induction Heating

Abstract

In No. 3 hot strip mill at JFE Steel East Japan Works (Chiba), mild steels are produced by the endless rolling process, in which rough rolled bars are joined and rolled continuously in the finishing mill. However, this process is not applied to high tensile strength steels because the alloy elements contained in those steels, such as silicon and manganese, form an oxide layer at the joining interface, disrupting the joining process. In laboratory joining tests, heating the joining surface until it melted resulted in discharge of the oxide layer from the interface, and steels that form oxide with a low melting temperature were successfully joined. A FEM flow analysis revealed that the viscosity of the oxide is the most important parameter for discharge. The low melting temperature of the oxide leads to low viscosity, resulting in the discharge of the oxide layer.