Numerical analysis on the medium-frequency induction heat treatment of welded pipe

The medium-frequency heat treatment of the high-frequency induction welded pipe was simulated using the finite element method. Results show that an hourglass-shaped temperature field is formed over the weld seam across the wall thickness. The influences of the current frequency, the current density and the distance between the coil and weld seam on the heating efficiency and the temperature difference across the thickness of weld seam are analyzed. The comparative metallographic experiments are conducted to verify the temperature field. The experimental results show that the medium-frequency heat-treatment process parameters have significant effect on the metallographic structure and mechanical properties. By a careful selection of the heat-treatment parameters it is possible to obtain a temperature field that would optimize the welding quality and the energy consumption. A theoretical method is proposed for the quantitative analysis of medium-frequency induction heat-treatment production.