Thermal-FSI based analysis of annealing process for a steel wire in a tube furnace

Tube furnaces are widely used in annealing to enhance the crystalline structures of metals under high temperature. This process mainly depends on high temperature as well as on heating and cooling rates at a specific time interval. Therefore, determining the temperature distribution inside a tube furnace is important to improve the heat treatment process. A 2D study was conducted to numerically investigate heat transfer in a tube furnace model; different gases with varying wire and gas velocities were used to estimate the temperature distribution in the furnace and wire. Higher wire velocity reduced the heat treatment process by decreasing the soaking zone length. The counter-flow arrangement of the sample wire and gas resulted in increased length of the cooling zone. The laminar flow in the tube furnace produced larger temperature gradients in radial directions. The tube furnace that used hydrogen gas as working fluid remarkably increased the heating and soaking zone lengths compared with the tube furnace that used nitrogen. The heat treatment process also depended on gas flow rates, and the increase in gas velocity led to an increase in heat transfer because of increased convection. The gas flow rate also affected the structural properties of the steel wire because of higher fluid pressure on the wire. One-way and two-way coupling methods were compared using temperature distributions in the tube furnace. Results showed that a numerical study of the annealing process is necessary before a practical application of industrial heat treatment processes can be conducted. (C) 2015 Elsevier Ltd. All rights reserved.