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Efficient production of increasingly popular high strength steel grades necessitates not just the ability to achieve a required coiling temperature, but to closely control the cooling path. The runout table plays an important role in producing steel strip which consistently meets precisely specified mechanical properties. Close inspection of the present control system used on British Steel Strip Products' Port Talbot Work's hot strip mill runout table showed that the main source of error within the system was inaccuracy in the temperature predictions used by the control system. These predictions were used as the basis for the feedfoward control system. Trials were carried out to assess the viability of using artificial neural network models instead of the present conventional mathematical model in order to increase the accuracy of temperature predictions. A methodology was developed so that data taken from the runout table could be used to build artificial neural networks capable of modelling the cooling that took place. The method used to select the training data was seen to be very important in obtaining an accurate model. Using this artificial neural network approach it was possible to develop models that were capable of predicting temperatures for groups of coils of similar grade material. The accuracy of these predictions were in general similar to the predictions provided by the present on-line model, and for one group of carbon manganese grades, they were significantly better. Finally, the overall conclusion from this work is that this approach in modelling the runout table cooling is a viable alternative in providing an on-line model, and details are given of the further work needed in order to fully optimise the benefits and reduce the risks associated with altering the present control system.

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This study examines four aspects of the use of ultrasonics in steel strip pickling: the cavitation process, the kinetics of scale removal, the relative significance of variables in ultrasonic pickling and the application of ultrasound in a pilot-scale operation. To ensure optimum location of transducers in relation to their cavitational effects, studies were carried out in water tanks using two techniques to map cavitational activity: resistance thermometry and quantified mechanical damage to coupons of lead or aluminium. Both techniques gave similar results. Thermometric mapping had the advantage of speed but the use of a panel of lead coupons provided more tangible evidence of the mechanical influence of ultrasound in water. A cylindrical bar transducer was the most effective of those tested and could readily be adapted for use in wide strip pickling. The kinetics of pickling were analysed using a Johnson-Mehl type equation. Time exponents 'n' were in the range 2.03 - 2.56 with activation energies in the range 42.18 - 50.54 kJ/mol. The process both in normal and ultrasonic pickling was envisaged to occur by progressive undercutting and fracture of the scale. The application of ultrasonics reduced completion times considerably. To explore the individual and linked influences of variables on the pickling process, and the effect of applying ultrasonics, a statistical factorial analysis was carried out. Acid temperature was found to be the most important single variable while the most significant interaction was that between acid temperature and acid concentration. An equation has been derived reflecting the influence of all the pickling variables and their interactions. Finally, to assess better the applicability of ultrasonics to full-scale commercial operations, tests were carried out on a large pilot plant funded as part of a European Coal and Steel Community project between British Steel plc and Hoogovens Staal. The results of the smaller tests were confirmed and, furthermore, the influence of ultrasound on inhibitor efficiency was found to be insignificant.

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No description available.

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Of the many recent developments in steelmaking technology, one of the most notable has been the introduction of 'ladle' or 'secondary steelmaking' processes. The present study has therefore sought to assess and to quantify these developments, especially in relation to production and consumption patterns for special steels in the Western World. Estimates have been made of the future levels of demand for special steels in relation to predictions of total crude steel production. Consideration has then been given to the formulation of quantitative projections of the process routes likely to be adopted for special steel production. Finally, using the derived projections for special steel demand and for the changes in process share expected, an assessment has been made of the future requirements for alloying elements and for refractory use in the steel industry with emphasis on special steel production.

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