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 ℃.

High-Temperature Wear and Frictional Performance of Plasma-Nitrided AISI H13 Die Steel

“…The hardness values approximately doubled in comparison to the heattreated die steel. The microhardness value increased due to the formation of nitrides of chromium and iron, as published in the author's previous works with different wear loads [18,19]. Visuttipitukul et al [21], Pellizzari et al [23], and Birol [24] mentioned that the supersaturation of the BCC matrix with nitrogen resulted in precipitation in the diffusion zone, which hardened the surface.…”

“…This process is environment-friendly, and minimum distortion of the components is ensured as the process is carried out at lower workpiece temperatures. Plasma nitriding imparts wear resistance to stainless steels and hot/cold-worked steels [14][15][16][17][18][19]. AISI H13 hot-forming tool steels are well-known candidates for fabricating dies in the hot-press-forming/forging industry.…”

The influence of plasma nitriding hardness treatment on the dynamic compressive behavior of the Hardox 400 at a wide temperature range

“…Based on the aforementioned studies and on other recent works on surface properties improvement by plasma nitriding, 14–19 and to the author’s best knowledge, no attention is paid to the effect of the thermal processes generated from the nitriding hardening on the overall mechanical behavior of Hardox steels, in particular the material flow stress and ductility. According to the manufacturer 20 and the research made by Multani et al, 21 Konat et al, 22 and Gallina et al, 23 thermal processes, as nitriding, generate an adverse structural changes in Hardox 400 steel which could affect the core material properties and reduce strength and hardness.…”