Influences of liners and magnetic flux concentrator on induced Joule heat in hot extruded billet

In the production of pipes by hot extrusion method,billets should be heated to a certain temperature before hot extrusion by induction heating.The segmented liners in the induction furnace can possibly affect the circumferential Joule heat generation,thus leading to an uneven temperature field.The commonly used magnetic flux concentrators (MFC) can increase the temperature on both ends of the billet.In this paper,the possible effect of liners and the factors affecting the utilization of the MFC,including the permeability,dimension and position,are all numerically studied and determined.