Abrasive impact wear and surface fatigue wear behaviour of Fe–Cr–C PTA overlays

The conventional Fe–Cr–C overlay is studied due to the lack of information regarding the response of this material system to impact wear conditions. Previously the same material system has been successfully used in erosion wear conditions. The high stress abrasive impact wear resistance and low and high surface fatigue wear behaviour of a Fe–Cr–C overlay (FeCrC—matrix) produced by plasma transferred arc welding (PTA) were studied. The overlays with varied PTA hardfacing process cooling parameters were tested. The cooling parameters were as follows: (1) active cooling—application of gas cooling of substrate during the welding process; (2) passive cooling—application of copper plate under substrate with constant temperature of 20 °C and (3) standard—cooling in the air. Different cooling time leads to differences in microstructure and formation of residual stresses (surface cracks, etc.). The abrasive impact testing reveals the difference in the overlays response to the cyclic stressing at high impact energy. The surface fatigue wear (SFW) testing is accompanied by the abrasive impact wear (AIW) testing. The SFW incorporates cyclic loading of the overlays surface with spherical indenter with radius of 10 mm at high loads, while in AIW testing the specimens are bombarded almost in normal direction with granite gravel particles (diameter of <6 mm) with the energy in the range of 0.14–0.52 J. The study proposes the relation between high energy impact/abrasive wear behaviour and the surface fatigue wear behaviour of Fe–Cr–C hardfacings produced under varying cooling conditions.