Salt Bath Nitrocarburizing Research Articles

Sliding wear behavior of nitrocarburized bearing steel

Four-ball tribological apparatus was employed to investigate the sliding wear behavior of bearing steel 52100 treated by salt bath nitrocarburizing and complex nitrocarburizing processes. The microstructures, phase identification, surface hardness and hardness profiles of specimens were analyzed by optical microscopy, X-ray diffraction and microhardness testing. The experimental results show that higher sub-surface hardness and hardness profiles were obtained by nitrocarburizing and complex nitrocarburizing, although their surface hardness was lower than that of commercial balls. It was also demonstrated that the ε-phase formed on the specimen surfaces had a significant effect on reducing friction coefficient but this treatment lowered the wear resistance. Complex nitrocarburizing increased the wear resistance. Both Nitrocarburizing and complex nitrocarburizing could upgrade the load-bearing capacity of treated specimens.

Microstructure and tribological behaviour of nitrocarburizing-quenching duplex treated steel

This paper explores salt bath nitrocarburizing and nitrocarburizing-quenching duplex treatment technologies. For comparison, a quenching-tempering treatment was also conducted. By means of metallographic examination, microhardness tests and X-ray diffraction analysis, the microstructures, phase structures, surface hardnesses and hardness profiles of 1045 steel treated by several techniques were investigated. The ball-on-block and ring-on-block apparatuses were employed to investigate the friction coefficient and wear-resistance respectively. The surface roughness was also measured by a profilometer. The experimental results indicate that a higher sub-surface hardness and a superior hardness profile are obtained by nitrocarburizing-quenching duplex process. This in turn improves the wear-resistance and fatigue strength, although the surface hardness is somewhat lower compared with that obtained by nitrocarburizing. It also demonstrates that the ε-phase formed on the steel surface has significant effects on reducing friction and improving wear-resistance. X-ray diffraction analysis shows that the phases at the nitrocarburized specimen surface are mainly ε-compound [Fe 3(N,C)] and small amounts of Fe 4N(γ′) and Fe 2–3(N,C). While the phases at the nitrocarburized-quenched specimen surface are very different from those at the nitrocarburized specimen. In this case, the ε-compound has decomposed almost completely and the nitrogen and carbon diffuse to the γ-Fe at the temperature of quenching to form the supersaturated solid solution which will become martensite containing nitrogen and carbon along with retained austenite after subsequent water cooling.

Present State of Salt Bath Nitrocarburizing for Treating Automotive Components

Present State of Salt Bath Nitrocarburizing for Treating Automotive Components

Model Description of Iron-Carbonitride Compound-Layer Formation during Gaseous and Salt-Bath Nitrocarburizing

Model Description of Iron-Carbonitride Compound-Layer Formation during Gaseous and Salt-Bath Nitrocarburizing

Influence of salt-bath nitrocarburizing on fatigue life: Eckert, A., Dengel, D. and Kunst, H. Hart. -Tech. Mitt.44, (5), 296–302, Sept.–Oct. 1989 (in German)

Influence of salt-bath nitrocarburizing on fatigue life: Eckert, A., Dengel, D. and Kunst, H. Hart. -Tech. Mitt.44, (5), 296–302, Sept.–Oct. 1989 (in German)

On the extension of the optical-mechanical analogy

The use of surface treatments is essential to increase the in-service lifetime of hot forging dies due to their improvement in terms of wear and fatigue resistances. Two thermochemical surface treatments (salt-bath nitrocarburizing and nitriding followed by post-oxidation) applied to a H13 steel have been studied in this paper. The effect of a deep cryogenic treatment on wear resistance has also been assessed.It was shown that the two applied surface treatments markedly improved the wear resistance of the steel as a result of surface hardening and the compressive residual stress field thus induced, along with the formation of surface layers of nitrides and oxides with excellent tribological features. These surface treatments also led to good performance when tested at high temperature simulated working conditions: no relevant stress relaxation and softening until 500 °C, but gradual stress relaxation and partial softening after prolonged exposure at 600 °C was observed. Furthermore, the application of a deep cryogenic treatment showed a significant reduction in the wear rate compared to that of conventional quenched and tempered H13 steel.

Plane problem on oscillation of a body under two surface-separating liquids

The use of surface treatments is essential to increase the in-service lifetime of hot forging dies due to their improvement in terms of wear and fatigue resistances. Two thermochemical surface treatments (salt-bath nitrocarburizing and nitriding followed by post-oxidation) applied to a H13 steel have been studied in this paper. The effect of a deep cryogenic treatment on wear resistance has also been assessed.It was shown that the two applied surface treatments markedly improved the wear resistance of the steel as a result of surface hardening and the compressive residual stress field thus induced, along with the formation of surface layers of nitrides and oxides with excellent tribological features. These surface treatments also led to good performance when tested at high temperature simulated working conditions: no relevant stress relaxation and softening until 500 °C, but gradual stress relaxation and partial softening after prolonged exposure at 600 °C was observed. Furthermore, the application of a deep cryogenic treatment showed a significant reduction in the wear rate compared to that of conventional quenched and tempered H13 steel.