On the improvement of the Charpy impact response of high-Mn steel (HMS) alloys via Ti addition for comminution circuits

High-Mn Steel (HMS) alloys due to their high impact toughness see extensive use in the comminution circuits in the mineral processing and bulk material handling industries. Higher throughput, a common practice being observed in the mineral processing plants, has increased the typical in-service stress conditions. Thus, the motivation for the current work was the need to improve the impact toughness of the commonly used steels in this application. This current work focuses on the influence of Ti addition to HMS alloys, on the microstructural characteristics and the deformation behaviour of the alloys when subjected to Charpy impact testing. The addition of Ti to the alloy composition of the HMS alloys, resulted in the in-situ formation of Titanium Carbide (TiC) particles during solidification, which further facilitated the refinement of the austenitic grain size. It was observed that, the refinement of the austenitic grains coupled with the dispersion of the TiC particles in the microstructure, contributed to the enhancement in the impact toughness; however, they concurrently reduced the lateral distortion and limited the extent of plastic deformation during impact loading. A detailed investigation of the strengthening mechanisms contributing to the impact toughness of the 0wt.% Ti and 0.15wt.% Ti alloys revealed that apart from the dispersion strengthening, the presence of the TiC particles in the 0.15wt.% Ti composite material contributed to the strengthening through the mechanisms of Orowan strengthening, load transfer and particle-stimulated nucleation of twins. The combined contribution of these additional strengthening mechanisms in the 0.15wt.% Ti composite bolstered the material's impact properties.