Surface engineering analysis of plasma-nitrided die steels

Abstract

In the current investigation, an effort was made to analyze the sliding wear and friction characteristics of the surface engineered hot forming tool steel. A surface treatment technique plasma nitriding was developed onto the surface of the hot forming tool steel namely AISI H13 with a view to reduce the friction coefficients and minimize wear. The treatment was done in various N2/H2 gas mixtures for the fixed time of 24 h and at a fixed temperature of 500 ℃. The phases formed on the plasma-nitrided surface have been identified by the X-ray diffraction technique. The surface morphology of nitrided specimens and the composition of the nitride particles have been analyzed using scanning electron microscopy/energy-dispersive spectroscopy techniques. Thereafter, the untreated and treated steel specimens were chosen to slide against high strength low alloy steel (actual workpiece material) at elevated temperatures. The tests were conducted on high-temperature tribometer under the constant load of 25 N at room temperature, 200 ℃, 400 ℃, and 600 ℃. The results have shown that the average friction coefficients and specific wear rate values decrease from room temperature to 400 ℃ and again increase at 600 ℃.