The technological instructions of most converter steel casting shops of modern metallurgical enterprises contain instructions for cutting slabs into to length using a fixed length increase factor that is directly dependent on shrinkage. This does not take into account the chemical composition of steel and the temperature of cutting slabs into exact lengths. At the same time, experience shows that for steels of different grades there is a discrepancy between the planned and actual values of the slab length. This problem required the creation of a mathematical model that makes it possible to determine the values of the linear shrinkage of the slab from cutting to complete cooling. On the basis of this model, a method for calculating the coefficient of increase in the measured length (cutting coefficient) of a slab during cooling from a cutting temperature to 30°C was developed. With the help of the proposed technique, the reduction in the length of slabs of grades 09G2S, 08PS, 22GU was studied. The paper also shows that the dependence of the cutting coefficient on the carbon concentration and temperature before cutting is linear. It was found that the effect of carbon concentration on shrinkage is significantly manifested only at high cutting temperatures (1000-1100°C). On the basis of the dependence obtained, a technical solution is proposed for automating the workplace of the operator of a gas cutting machine (CCT) of the shop for casting converter steel of a modern metallurgical enterprise.
Keywords: shrinkage, slab, mathematical model, cutting coefficient, cutting, thermophysical properties