By analysing the factors that affect oxygen consumption during the basic oxygen furnace steelmaking process, a multiple linear regression model for predicting the oxygen blowing quantity was obtained on the basis of actual production data. Additionally, an oxygen balance model for prediction of the oxygen blowing quantity was established on the basis of oxygen balance. These two models were amalgamated to establish an integrated model for prediction of the oxygen blowing quantity. The average relative error of the integrated model is ,1%, and the hit rate of the integrated model is 97?14% when the relative errors of the model are within 5%.Relative to the multiple linear regression and the oxygen balance models, the integrated model may provide a more accurate prediction of the oxygen blowing quantity, and thus represents a good reference point for actual production.

A software to simulate the solidification, heat transfer and water flowrate distribution in slab continuous casting was developed by establishing a mathematical model for the heat transfer and solidification in medium thickness slab casting. This model was validated by pin shooting and surface temperature measurement experiments. A reasonable target surface control temperature was found by testing the high temperature mechanical properties of Nb bearing ship plate steel,and then the water flowrate of each loop of the secondary cooling zone was determined by the software. The influence of uneven secondary cooling in the slab width direction on the quality of the slab was also investigated, which provided data for the optimisation of the secondary cooling of the slab caster. On the basis of the above research, an optimisation scheme for a secondary cooling system was proposed. Experimental results showed that the quality of the slab was significantly improved after optimisation. The centreline macrosegregation was reduced, and the ratio of equiaxed grains was increased by 3?18%. In addition, the transverse cracking of the slab was almost eliminated.

The liquidus temperature of steel is greatly affected by its chemical composition; therefore, the value of the liquidus temperature can vary among different types of steel. In this study, on the basis of the concept of differentiation, the Fe-i binary phase diagram is analyzed using Photoshop image processing software. The effects of eleven common alloying elements (C, Si, Mn, P, S, Ca, Ni, Cu, Cr, Nb, and Mo, whose content is between 0%～4%) on the melting point of pure iron are analyzed. This analysis proves the following assumption to be incorrect: the relationship between the change in liquidus temperature and the content of element i is a linear relationship; this assumption is the basis of traditional liquidus calculation models. A new model for calculating the liquidus temperature of steel is established in this study. As compared to data from other literature, the model proposed in this paper has good generality and the calculation error of the liquidus temperature of steel is between ?3 and 4 °C, which is acceptable. A statistical analysis of the experimental data for different steel grades (obtained from Laiwu Special Steel) using the developed model showed that 87.2% of the absolute deviation values of the temperature are within 4°C. This result shows the model to be both reasonable and credible.