Significant acceleration of nitriding kinetics in pure iron by pressurized gas treatment

Wang, Bo; Fu, Weijie; Dong, Fengguang; Jin, Guofeng; Feng, Weiwei; Wang, Zhenhua; Sun, Shuhui

doi:10.1016/j.matdes.2015.07.013

Cited by 21 publications

(13 citation statements)

References 25 publications

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“…However, for structures with complicated shapes, such as crankshafts, standard fatigue testing is time consuming and expensive. In addition, other factors such as the manufacturing process [ 10 – 12 ], control strategy [ 13 – 15 ], surface strengthening [ 16 – 17 ] will also create substantial impacts on the fatigue strength of a part, which will result in some errors during the fatigue strength prediction.…”

Section: Introductionmentioning

confidence: 99%

A new stress field intensity model and its application in component high cycle fatigue research

Sun

2020

PLoS ONE

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Fatigue limit load is one of the most important and concerned factors in designing and manufacturing critical mechanical parts such as the crankshafts. Usually, this governing parameter is obtained by experiment, which is expensive, time-consuming and only feasible in analyzing the case of simple structure. Still, there's a big obstacle to clear to get the fatigue limit load of a sophisticated structure effectively and efficiently. This paper applied the stress field intensity theory to make quick component fatigue limit load predictions. First, the field diameter of a given crankshaft was determined based on its limit stress state and a stress distribution fitting approach. Then, this parameter was used to predict the high-cycle bending fatigue limit load of a new crankshaft composed of the same material. Finally, a corresponding experimental verification was conducted to evaluate the accuracy of the predictions. The results indicated that the original stress field intensity model may not be suitable due to the errors in the predictions, which can be attributed to the structural features. The new model proposed in this paper can provide higher accuracy in quick fatigue load prediction, making it superior to the traditional model in engineering application.

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Section: Introductionmentioning

confidence: 99%

A new stress field intensity model and its application in component high cycle fatigue research

Sun

2020

PLoS ONE

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“…Keeping other nitriding conditions the same, the higher the pressure, the thicker the case-depth of nitrided layers. For a sample nitrided by PGN under 6 atm, the efficiency is nearly 10 times higher than that for conventional nitriding under atmospheric pressure [22,23,24].…”

Section: Introductionmentioning

confidence: 99%

“…The compound layer is beneficial for resistance against wear and corrosion. The diffusion zone can increase the fatigue resistance of gears; wear resistance can also be enhanced if the alloying element nitrides are precipitated in the diffusion zone [23,24]. Up to now, many studies have reported on the gas nitriding process.…”

Section: Introductionmentioning

confidence: 99%

Gradient Microstructure in a Gear Steel Produced by Pressurized Gas Nitriding

Yang

Zhang

et al. 2019

Materials

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A tempered martensitic gear steel (18CrNiMo7-6) sample was nitrided on two sides using a 5 atm pressurized gas at 530 °C for five hours. The nitrided sample was characterized by means of microhardness, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. A microhardness gradient was identified over a distance of 1000 µm with hardness values from 900 HV0.1 at the surface to 300 HV0.1 in the center matrix. The gradient microstructure was mainly divided into three zones: (i) a nitride compound layer at the top surface (~20 µm thick), (ii) a diffusion zone with containing precipitates (~350 µm thick), and (iii) the center matrix of the tempered martensite. Compared with carburized sample, the harder surface of the nitrided one ensures a better performance of the present pressured gas nitrided gears.

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“…Gas nitriding (GN) is a thermochemical surface treatment, which has been widely used for components made of steel, to improve the surface hardness, corrosion and wear resistance [2][3][4]. In recent years, GN has become one of the most widely used surface engineering techniques, owing to its simple operation and excellent applicability to a wide range of steel grades, as well as due to the small dimensional changes of nitrided workpieces [2].…”

Section: Introductionmentioning

confidence: 99%

Effect of Double Stage Nitriding on 34CrAlNi7-10 Nitriding Steel

et al. 2017

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In this study, effect of double stage gas nitriding of 34CrAlNi7-10 steel was analyzed. Nitriding processes were carried out in two stages. in the first stage, samples were nitridied at 500• C for 10 h and then in second stage nitriding process was continued at 530 and 550• C for 20 h. During both stages, the nitrogen activity on surface was controlled by the nitriding potential, which is a thermodynamical control parameter for controlled gas nitriding process. The nitriding potential was kept constant, at value of 10, during the first stage and was varied in the range of 3.2-0.2, for both nitriding temperatures, in the second stage. The presence of nitrides, formed on the surface of test materials was determined by XRD analysis technique. The morphology of nitrided layer was studied by optical microscopy. The microhardness of the surfaces of nitrided samples in HV1 was between 955 and 1029. The measurements have shown that the thickness of the compound layer (white layer) has varied between 6.85-23.90 µm and that the growth of the white layer and microhardness gradient were strongly affected by the nitriding potential and the temperature. Diffusion depths as Nht(HV) for Vickers Hardness were determined and compared.

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Significant acceleration of nitriding kinetics in pure iron by pressurized gas treatment

Cited by 21 publications

References 25 publications

A new stress field intensity model and its application in component high cycle fatigue research

A new stress field intensity model and its application in component high cycle fatigue research

Gradient Microstructure in a Gear Steel Produced by Pressurized Gas Nitriding

Effect of Double Stage Nitriding on 34CrAlNi7-10 Nitriding Steel

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