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

Abstract

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.

Numerical Simulation of Wire Rod Cooling in Eutectoid Steel under Forced-Convection

“…The composition was determined by optical emission spectrometry with SPECTROMAX LMM14 (Spectro, Kleve, Germany). The wire rod section was machined to obtain cylindrical specimens of 0.01 and 0.015 m in diameter, typical diameters for high-carbon steel wire rod produced in industrial scale [1], with a length of 0.040 and 0.060 m, respectively, to maintain the length/diameter ratio equal to four and ensure the heat transfer in the radial direction [19]. The specimens were instrumented with a 1/16" type K thermocouple, placed on the surface of the specimen to measure thermal history with a TempScan/1100 data logger and an acquisition rate of 10 data per second.…”

“…Fully pearlitic high carbon steels are employed in applications that demand high tensile strength and ductility such as tire reinforcements, saw cables, prestressed concrete, and piano wires [1,2]. These mechanical properties are closely related to the interlamellar spacing between the ferrite and cementite which compose the pearlite; as this parameter decreases, the plastic limit and the maximum yield stress increase [3][4][5][6].…”

Effect of Air Temperature on the Thermal Behavior and Mechanical Properties of Wire Rod Steel during Stelmor Cooling

“…Thirdly, the heat of the wire ring was dissipated into the ambient via radiation. Although geometric factors including the ring pitch, the ring shape, and the distance from the ring to surrounding mechanical components affect the radiation, 43) the radiative heat transfer coefficient is generally calculated as follows: where ε s is the total emissivity including the shape factor,…”

DETERMINATION OF THE VALUES OF MICROSTRUCTURAL AND MECHANICAL PARAMETERS OF A PEARLITIC 0.7%C-0.60/0.70%Mn STEEL WIRE ROD ENABLING TO ACHIEVE HIGH ABILITY TO DRAWING WITH THE USE OF LARGE CROSS SECTION REDUCTION

“…When determining the cooling parameters for wire rods, the effect of recalescence, i.e. heat generated during strongly exothermic pearlitic transformation, should be taken into account, which should be additionally removed in the process of wire rod cooling [14].…”