Surface Hardening of Steel by Nitriding Method

Takase, Takao

doi:10.2355/tetsutohagane1955.66.9_1423

Cited by 15 publications

(6 citation statements)

References 3 publications

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“…It decreases friction loss. Most reports have focused on the hardness pro le of the diffusion layer to improve bending fatigue strength in low alloy steels [1][2][3][4][5] . However, the compound layer also affects the fatigue strength.…”

Section: Introductionmentioning

confidence: 99%

Effect of Compound Layer Thickness Composed of γ'-Fe<sub>4</sub>N on Rotated-Bending Fatigue Strength in Gas-Nitrided JIS-SCM435 Steel

Hiraoka

Ishida

2017

Mater. Trans.

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The rotating bending fatigue strength of gas nitrided JIS-SCM435 steel was evaluated to nd the thickness that gives the highest bending fatigue strength. Four specimens were used that had different compound layer thicknesses composed of γ (-Fe 4 N) phase: 0, 2, 10, and 20 μm. The composition of γ phase was more than 70% of the volume of the compound layer in the specimens. The increment of the fatigue strength at 10 5 -10 7 cycles was remarkably high when the compound layer thickness was from 0 to 10 μm and gradually increased from 10 to 20 μm. The increment of the fatigue strength was caused by the increment of the γ phase thickness and the compressive residual stress depth as the compound layer thickness increased. The gradually increasing fatigue strength of more than 10 μm thickness was responsible for the porous layer thickness increasing and the compressive residual stress reducing on the surface as the compound layer thickness increased. These ndings show that the fatigue strength of gas-nitrided JIS-SCM435 steel composed of γ phase depends on not only the compound layer thickness but also the porous layer thickness and the compressive residual stress of the compound layer.

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Section: Introductionmentioning

confidence: 99%

Effect of Compound Layer Thickness Composed of γ'-Fe<sub>4</sub>N on Rotated-Bending Fatigue Strength in Gas-Nitrided JIS-SCM435 Steel

Hiraoka

Ishida

2017

Mater. Trans.

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“…It is generally known that the absolute value of fatigue strength is related to diffusion layer of nitrided irons and steels [15,16]. According to the hardness results, it can be seen that the diffusion layers of γ' phase and transformed γ' phase nitrides are almost the same, and only that of ε and γ' phase nitride was relatively thick.…”

Section: Fatigue Test Resultsmentioning

confidence: 93%

“…Recently, many studied have been conducted to improve the fatigue strength of irons and steels by gas nitriding [11][12][13][14]. However, most of these studies have documented that thick diffusion layers have a significant effect on increased fatigue strength [15,16]. On the other hand, some studies report that iron nitride formed on the surface rather than diffusion layer affects the fatigue strength [17,18].…”

Section: Introductionmentioning

confidence: 99%

The Effect of the Transformation of ε-Fe2-3N into γ′-Fe4N Phase on the Fatigue Strength of Gas-Nitrided Pure Iron

Kim

Yoon

Kim

et al. 2020

Metals

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The effect of the iron nitride phases, ε-Fe2-3N and γ′-Fe4N, on the fatigue strength was investigated. Pure iron was used to observe only the effect of nitride, excluding the effects of factors, such as residual stress, depending on the alloy composition and microstructural change according to working on the fatigue strength. In this work, ε and γ′ phases were respectively grown at a time on the surface of the pure iron specimens using the appropriate nitriding potential KN, the mixture rates of ammonia and hydrogen gases, at same temperature of 570 °C according to the Fe-N Lehrer diagram. Another γ′ phase was prepared by first growing the ε phase and then transformed from ε phase into γ′ phase by changing the KN at the same temperature of 570 °C in the 2-stage gas nitriding. The fatigue strengths of the iron nitride consisted of ε and γ′ phases, γ′ phase, and γ′ phase grown by the 2-stage gas nitriding were evaluated, respectively. As a result, first, it can be seen that the diffusion layer of ε phase was deeper than γ′ phase, but fatigue strength was lower. On the other hand, fatigue strength of both the γ′ phases are higher than that of the ε, and the fatigue strength of γ′ phase nitride grown by 2-stage gas nitriding was almost similar to that of γ′ phase nitride grown at a time, i.e., fatigue strength was not significantly related to diffusion depth and depended on nitride phases in this study. Secondly, we cannot clearly conclude that there was the difference in fatigue strength according to the thickness of nitride layer consisted of γ′ phase. However, it is clear that when ε phase was transformed to γ′ phase, fatigue strength had the same level as γ′ phase formed at one time.

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“…One of the methods is gas nitriding with ammonia. However, this method requires to heat up materials over 50 hours and produces fragile compound layer on the surface [1]. Another method is ion nitriding, which is carried out in a nitrogen-hydrogen gas mixture at several Torr pressure.…”

Section: Introductionmentioning

confidence: 99%

Generation of Spiral Shape Nitrogen Recombining Plasma for Atomic Nitrogen Source

Asaoka

Ohno

Hayashi

et al. 2019

Plasma and Fusion Research

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We propose a new method using a spiral shape nitrogen plasma with a long magnetic connection length to produce high density nitrogen (N) atoms for nitriding application. A high density N molecular ion plasma was generated by DC discharge and is transported along a long spiral magnetic field line. As a result, the electron temperature drops along the magnetic field to be low enough to produce dissociate recombining plasma, where dissociative recombination would occur to generate N atoms. 2D Langmuir probe measurement showed that the electron temperature and density decreased along the magnetic field. Optical emission spectroscopy showed the ratio of the atomic N and N molecular emission intensities increased with a discharge power. The ground state N atom density was estimated by analyzing the atomic line intensity.

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Surface Hardening of Steel by Nitriding Method

Cited by 15 publications

References 3 publications

Effect of Compound Layer Thickness Composed of γ'-Fe<sub>4</sub>N on Rotated-Bending Fatigue Strength in Gas-Nitrided JIS-SCM435 Steel

Effect of Compound Layer Thickness Composed of γ'-Fe<sub>4</sub>N on Rotated-Bending Fatigue Strength in Gas-Nitrided JIS-SCM435 Steel

The Effect of the Transformation of ε-Fe2-3N into γ′-Fe4N Phase on the Fatigue Strength of Gas-Nitrided Pure Iron

Generation of Spiral Shape Nitrogen Recombining Plasma for Atomic Nitrogen Source

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