Inverse analysis applied for determination of strain–stress curves for steel deformed in semi-solid state

Abstract

The integrated casting and rolling of plates in processes such as ISP or AST is the latest and very efficient method of hot strip production. The subject of the presented article is the modelling of steel behaviour at temperatures characteristic for the mentioned rolling technologies, which exceed the standard hot rolling temperature range. Numerical modelling can be very helpful in developing ‘know how’ theory for the mentioned processes. One of the most important relationships having a crucial influence on the metal flow path is the strain–stress curve. It is not easy to construct isothermal curves for a selected temperature range. The inverse method, which is usually applied for calculation of the real strain-stress relationship, needs a good mathematical model describing the plastic behaviour of the material. The model presented in the current article fills the gap in the modelling of plastic deformation of semi-solid materials. The methodology of constructing strain–stress curves is presented, as well. On the other hand, the mathematical modelling should be closely related to experiments. The only well-known method allowing laboratory tests in the discussed temperature range (over 1400°C) is the deformation of cylindrical samples using GLEEBLE thermo-mechanical simulator. However, experiments of steel deformation in semi-solid state by using this machine are very expensive. Therefore, application of a dedicated computer simulation system with an inverse method makes the tests possible in the first place and it also results in lowering testing costs.