Assessment of technological plasticity of high-Mn steels in SICO test

The tests were carried out on two newly developed high-manganese steel grades (27Mn-4Si-2Al-Nb and 24Mn-3Si-1.5Al-Nb-Ti). The developed chemical composition of the tested steels ensured obtaining an austenitic matrix. In order to determine the technological plasticity of the tested steels, the SICO (Strain Induced Crack Opening) test was carried out using samples with a diameter of 6 mm and a length of 76 mm. The tests were performed on a Gleeble 3800 thermomechanical simulator. The samples were deformed in the temperature range from 1180 ℃ to 1240 ℃ in steps of 20 ℃, at a strain rate of 0.1 s⁻¹, 1 s⁻¹ and 10 s⁻¹. Based on the tests performed, the values ​​of critical circumferential strains (for the applied deformation parameters) were determined, i.e. the smallest circumferential strains that cause the sample to crack. The SICO tests performed showed that with the increase of temperature and strain rate, the determined values ​​of circumferential strain increase, with higher values ​​for steel 24Mn-3Si-1.5Al-Nb-Ti. Samples made of steel 27Mn-4Si-2Al-Nb deformed at 1240℃ were completely destroyed, regardless of the applied strain rate.