An Approach to Heat Transfer Analysis of Wire Loops Over the Stelmor Conveyor to Predict the Microstructural and Mechanical Attributes of Steel Rods

To understand and predict the microstructure evolution in various grades of steel, a heat transfer coupled with phase transformation model has been formulated with an enhanced stelmor cooling module. This module is capable of handling both blower assisted high cooling and retarded cooling using hoods. The stelmor module incorporates the change in ring spacing of the wire loops on the stelmor due to a change in mill speed and conveyor speed of the wire rod mill. A geometrical approach to convective and radiative losses taking into account the void fraction and shape factor of wire loop is reported. This makes the model robust by strengthening the heat transfer formulation. This paper deals with the correlation of wire rod mill process parameters on the cooling curve of wire rods. The cooling of wire rods is dependent on the stelmor operating parameters. Commercial high carbon grades require high capacity blowers for efficient cooling to refine the pearlite microstructure and impart greater strength. Welding grade wire rods (low carbon grades) on the other hand require retarded cooling to increase the ferrite grain size and decrease the ultimate tensile strength.