Uniform Surface Temperature Cooling of Wire Rod Using Aqueous Surfactant Solutions

ABSTRACT

This paper presents use of aqueous solutions of nonionic surfactant for cooling of 5.5 mm diameter low carbon steel wire rod. The surfactant in its pure form was injected in water stream upstream to the water box nozzles and was not recirculated. Variations in the wire rod surface temperatures at the laying head with time and water switching on and off conditions for experimental water flow and aqueous surfactant solution flows with surfactant concentrations ranging from low to high were recorded. It was observed that wire rod surface temperature fluctuations were reduced - smoothened out significantly with low surfactant concentration and were eliminated at high surfactant concentration. Because of its better wetting and spreading characteristics, surfactant reduces contact angle such that water spreads better on the hot steel surface. This leads to improved uniformity in steel surface temperature during cooling by water. The temperature fluctuations are correlated directly with surface finish of wire rod such that smoothest surface corresponds to the elimination of temperature fluctuations. In addition, there is no significant change in the properties of wire rod with % elongation change observed as maximum, which is 8.2% higher for wire rod surface compared to the wire rod cooled by water. Finally, SEM photographs of microstructures show variations, which primarily depict suppression of nucleation in the grain matrix with aqueous surfactant solution cooling the wire rod surface.

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