Thermo-mechanical properties of ultra high strength steel 22SiMn2TiB at elevated temperature

The flow behavior and the thermo-mechanical properties of 22SiMn2TiB at elevated temperature were investigated isothermally by the uniaxial tensile test. The steel exhibited a high hot ductility with the value of the percentage reduction of area higher than 80% at the selected temperatures. The hot ductility showed significant dependency on the deformation temperature and appreciable dependency on the austenitization temperature. The stress level decreased with the increasing deformation temperature and the decreasing strain rate. It was found that the ausformed martensite was strengthened by the deformation of austenite at the temperature above 850 °C, while the diffusion transformation was promoted at the temperature below 800 °C. The flow stress could be satisfactorily illustrated by the Zener–Hollomon parameter in an exponent-type equation. Based on the Z-parameter, the Hollomon equation was revised to describe the stress–strain correlation. The predicted results were well consistent with the experimental results.

Research highlights
► The hot ductility exhibited significant dependency on deformation temperatures.
► Ti(C, N) precipitates played an important role in the hot ductility of the steel.
► Diffusion transformation deteriorated the hot ductility at lower temperatures.
► The constitutive equation could give an accurate estimate for the flow behavior.