Comparison of cavitation erosion and sliding wear resistance of welded CoCrWC and NiCrBSi hardfacings, AISI 316L stainless steel, and S235JR mild steel

The main objective of the study was to comparatively analyse the cavitation erosion resistance and dry sliding wear resistance of two hardfacing alloys: NiCrBSi (a self-fluxing alloy) and CoCrWC (Stellite 6), as well as two popular steels -S235JR mild steel (approx.0.17% C) and stainless steel (AISI 316L).CoCrWC was hardfaced using the TIG (tungsten inert gas) welding method and NiCrBSi using the oxy-flame powder welding method on a mild steel substrate.Cavitation studies were carried out according to ASTM G32 standard with a standoff of 0.5 mm.Sliding wear resistance tests were carried out using the ball-on-disc method (100Cr6 steel counterball).CoCrWC hardfacing shows the highest cavitation erosion and sliding wear resistance.Therefore, the maximum depth of erosion rate was the lowest for CoCrWC < NiCrBSi < AISI 316L < S235JR.Sliding wear resistance is shown in the following order, starting with the minimal material loss: CoCrWC > NiCrBSi > S235JR > AISI 316L.The lowest coefficient of friction (COF) was observed for S235JR (COF=0.467),while the other samples exhibited comparable COF values in the range 0.605-0.698.Microstructure and hardness ratio critically affect wear; accordingly, soft single-phase materials suffer high losses in sliding wear and cavitation erosion tests.Wear mechanisms were studied using SEM.Cavitation erosion resistance relies on the metallic matrix's capacity to absorb loads and resist fatigue.Erosion begins with deformation of the metallic phase at phase interfaces, leading to detachment of the weakened material.In hardfacings, carbides and borides are dislodged once they lose support, ultimately forming pits, craters, and cracks through fatigue-induced detachment.Sliding wear behaviour is dictated by microstructure.Hard particles embedded in a matrix minimise abrasive wear and reduce material loss.In contrast, soft, single-phase steels undergo abrasive wear debris accumulation, leading to adhesive wear, raising wear rates.AISI 316L suffers the highest wear -its oxidised debris spalls off -whereas S235JR benefits from a well-adhering tribofilm and lower material loss.CoCrWC and NiCrBSi coatings showed higher cavitation and sliding wear resistance than reference steels.