Numerical Analysis of Welding Phenomena in High-Frequency Electric Resistance Welding

Abstract

High-frequency electric resistance welded pipes are used for high-grade line pipes. To address the significant need for weld seam reliability, it is important to clarify the associated welding phenomena. In this study, a numerical analysis model is developed to clarify the behaviours of the molten steel and oxide in HFW pipes. The temperature distribution of the HFW is calculated using electromagnetic and heat conductive finite element analysis methods. The molten metal and oxide flows are analysed by modelling heat conductive and plastic flows. The movement behaviour of the oxides in the molten steel is successfully analysed with this technique. The material properties as a function of the temperature of the steel pipe are calculated using general-purpose simulation software. With pressurisation by the welding rolls, the molten steel moves to the upper part, and the oxide, which exists in the internal parts, rapidly decreases such that almost all of the oxide transitions to the excess metal part. The internal oxide content rate after pressurisation at 0.08 m/s is less than 0.01. To decrease the oxide content, the pressurisation rate must increase such that the molten steel and an oxide pressurised at high temperatures transition to the excess metal part.