Torsion tests allow studying the rheological properties of materials over a wide range of strain and strain rate values as well as temperature. A key moment in construction of hardening curves is the interpretation of experimental data, which are usually the torque - angle of twist curves. However, there are a number of independent methods to obtain interpretation of experimental data. In addition, there is no single approach to determining the degree of equivalent strain in torsion test. The aim of this paper is to review existing hardening curves definition methods in torsion test and to examine them with the use of finite element modelling.