Instrumentation and simulation of industrial steel wire rod cooling line

A coupled thermal and metallurgical mathematical model has been developed to simulate the Stelmor process for controlled cooling of steel wire rod. The model predicts the through section microstructure, which is subsequently used to estimate the mechanical properties, in terms of ferrite fraction, ferrite grain size, and interlamellar pearlite spacing. Plant trials were conducted to evaluate heat transfer coefficients for the water and forced air cooling stages of the process in terms of the process parameters. To enable the development of a control model, the effect of individual process parameters, including their extreme settings, on rod temperature distribution was studied. An inverse modelling approach has been used to optimise the value of the heat transfer coefficient. The model results were compared with plant trials for a range of rod diameters, rolling speeds, number of active water boxes, and the operation ratio of the Stelmor fans. This validation was performed for three carbon - manganese steel grades (0.07-0.67%C) with rod diameters of 5.5-14.0 mm. A good agreement between the predicted and measured thermal behaviour of the rod was achieved.