Wear and Friction Behavior of Plasma Nitrided Hot Forming Tool Steels
In this work hot forming tool steels namely AISI H11 and AISI H13 were plasma nitrided at 450°C substrate temperature for 24 hours. The cross-sectional microstructures of the plasma nitrided specimens were examined by optical microscopy (OM). A diffusion layer without the white layer was formed on the material by controlling the nitriding parameters. Microhardness measurements were performed on the surface and through the diffusion layer for each nitrided material. The as-nitrided specimens were characterized by X-ray diffraction (XRD) analysis and Scanning Electron Microscopy (SEM). Further wear and friction properties of the untreated and the plasma nitrided specimens were studied on Pin-on-Disc tribometer at room temperatures under dry sliding conditions. Total wear volume and the friction coefficients were evaluated. The worn specimens were critically examined with an aim to propose mechanisms behind wear behavior of the coatings. The results showed the increased wear resistance by plasma nitrided tool steels.