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High-temperature tribological studies of plasma-nitrided tool steels

ABSTRACT During hot forging/forming operations, the die surface and near surface region is subjected to severe wear. The failure of dies originates from the surface region. In this research work, plasma nitriding was done on two hot forming tool steels namely AISI H11 and AISI H13. The aim is to develop a hard and wear resistance surface required for hot forming operations. The mechanical and microstructural properties of the developed nitrided layer were critically examined. Thereafter the tribological characteristics of the untreated and plasma-nitrided specimens were studied on high-temperature pin-on-disc tribometer under the constant load of 25 N, sliding speed 0.5 m s−1, sliding distance of 1500 m at different temperatures ranging from room temperature to 600°C. The results showed that the main wear mechanisms is predominantly adhesive at room temperatures and 200°C and a combination of adhesive and abrasive at elevated temperatures (400°C and 600°C).