Improvement on pitting wear resistance of gears by controlled forging and plasma nitriding

• DOI: 10.1016/j.jmrt.2022.04.122
• Publication Date: 2022-05-02T15:57:26Z
• Authors: Rafael Luciano Da...; Valcir Marques de...; Leonardo Fonseca ...; Carlos Henrique d...; Julio Cesar Klein...; Carla Adriana The...; Alexandre da Silv...
• Keywords: Forged gears; Mining engineering. Metallurgy; TN1-997; Pulsed plasma nitriding; 02 engineering and technology; Fracture toughness; Compound layer; Pitting wear resistance; 0210 nano-technology; Bainitic steel

In the present investigation, use of a bainitic steel for forged gears applications and suitability different plasma nitriding treatments is discussed. The were forged, machined, ground, polished, nitrided at 500 °C with three sets N2–H2 gas mixtures, containing 5, 24, 76 vol.% N2, to develop case approximately 300 μm depth. Gears characterized before after concerning phase composition, microstructure, microhardness, fracture toughness, residual stresses states. Pitting wear tests performed on standard Forschungsstelle für Zahnräder und Getriebebau (FZG) test rig. 24 N2 formed biphasic compound layer ε-Fe2-3(C)N γ′-Fe4N. As volume fraction nitrogen in mixture was decreased, detected content γ′-Fe4N increased, but monophasic only reached 5 N2. rich composition increased surface hardness decreased toughness layer, as they have more ε-Fe2-3(C)N. diffusion zone surfaces showed compressive stresses. best performance obtained due better combination between hardness, stresses, thickness. ten times improvement over non-nitrided gears, while an point seven five four times.