High Temperature Mechanical Properties of the As-cast Low Carbon Steels and Their Prediction

Steel undergoes multiple phase transformations during casting and various forces of technological origin affect a slab in the casting machine. As a consequence of these infl uences, various types of defects arise during the casting process [1 5]. The slab surface quality is a crucial factor for quality of the end products, especially of the fl at ones. Plasticity of the steel is a further, very important parameter infl uencing the slab surface quality. A high plasticity enables relaxation of various stresses and therefore causes minimum changes in the surface relief, without formation of crack like defects. Temperature course of plasticity evaluated by the reduction of area values in the temperature range from about 900 °C up to the maximum solidus temperatures is for some of the investigated steels schematically depicted in Figure 1. The plasticity decrease regions under the tx as well as above the th temperatures are critical for formation of defects, Figure 1. High temperature properties of as-cast material, as reduction of area and strength, were tested in a temperature interval from 850 °C up to the melting temperature on measuring equipment provided with high frequency heating. The software for prediction of the high temperature plasticity development based on physical metallurgical and regression analyses was elaborated for the cast state of low carbon steels. The program was verifi ed by using experimentally estimated values.