The Effect of Oxidation Process After Nitrocarburization on Tribological Properties of AISI 4140 Steel

Kaplan, Yavuz; Yildirim, Abdulbaki; Aksöz, Sinan

doi:10.2339/politeknik.585031

Cited by 4 publications

(2 citation statements)

References 17 publications

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“…AISI 4140 çelikleri, karbon içeriği açısından sertleşmeye uygun ve işlemin sonunda belirli yükler altında yüksek tokluk ve aşınmaya karşı yüksek direnç özellikleri sergileyen yapısal alaşımlı çeliklerdir [13]. Otomotiv ve uçak yapımı, yivli şaft, aks mili ve kovanı, krank mili ve benzeri yüksek süneklik isteyen parçaların yanı sıra dişli çark içeren uygulamalarda da yaygın olarak kullanılmaktadır [1,[14][15][16]. Literatürde nitrokarbürleme işlemi kullanılarak AISI 4140 ıslah çeliklerinin diğer çelik türlerine göre, özellikle nitrasyon çeliklerine daha yakın mekanik özellikler kazanabildiği ifade edilmiştir [16][17][18][19][20]…”

Section: Malzeme Ve Metod (Materials Andunclassified

“…Otomotiv ve uçak yapımı, yivli şaft, aks mili ve kovanı, krank mili ve benzeri yüksek süneklik isteyen parçaların yanı sıra dişli çark içeren uygulamalarda da yaygın olarak kullanılmaktadır [1,[14][15][16]. Literatürde nitrokarbürleme işlemi kullanılarak AISI 4140 ıslah çeliklerinin diğer çelik türlerine göre, özellikle nitrasyon çeliklerine daha yakın mekanik özellikler kazanabildiği ifade edilmiştir [16][17][18][19][20]…”

Section: Malzeme Ve Metod (Materials Andunclassified

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Nitrokarbürleme ve Son Oksidasyon Proseslerinin AISI 4140 Çeliğinin Mikroyapı ve Yüzey Özellikleri Üzerine Etkisi

YİLMAZ¹,

PEHLİVANLI²,

ERKAN³

et al. 2023

Politeknik Dergisi

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AISI 4140 steel is in the class of medium carbon low-alloy steels and is widely used in industry due to its high hardenability and being a relatively economical steel. AISI 4140 steel is also among the steels that can be nitrided. With the nitriding process, thanks to the hard nitride layer obtained on the surface, not only a wear-resistant surface is provided, but also an increase in fatigue strength. In this study, the microstructural and surface properties of AISI 4140 steel, which has been treated with low pressure gas nitrocarburizing and post-oxidation process at different times, has been investigated. For this aim, AISI 4140 steel samples were austenitized at 850 °C for 60 min and quenched into oil at 60 °C. After quenching, the samples were tempered at 630 °C for 60 min. Gas nitrocarburizing process steps; pre-oxidation at 350 °C for 45 minutes, nitriding at 550 °C for 90 minutes and nitrocarburizing at 550 °C for 480 minutes were applied, and then the samples were subjected to post-oxidation using steam for 45 to 180 minutes. Microstructural characterization studies were performed by optical microscope, scanning electron microscope (SEM), energy-dispersive X-ray spectrum analysis (EDX), X-ray diffraction (XRD) analysis, microhardness and surface roughness measurements. The X-ray analysis results revealed that the surface layer of the samples consisting of iron-nitride phases of ɛ-Fe2-3N and ɣ’-Fe4N during nitrocarburizing and iron oxide (Fe3O4). It was determined that the iron oxide (Fe3O4) layer thickness increased with increased post-oxidation time. Among the AISI 4140 steel samples that nitrocarburized and post-oxidized, the best combination of hardness depth, surface hardness, and surface roughness was obtained after 150 minutes of post oxidation.

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Section: Malzeme Ve Metod (Materials Andunclassified

Nitrokarbürleme ve Son Oksidasyon Proseslerinin AISI 4140 Çeliğinin Mikroyapı ve Yüzey Özellikleri Üzerine Etkisi

YİLMAZ¹,

PEHLİVANLI²,

ERKAN³

et al. 2023

Politeknik Dergisi

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Effect of post-oxidation times in the nitrocarburizing process on the wear behavior of an AISI 4140 steel

Yilmaz,

Erkan,

Akar

et al. 2024

Materials Testing

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This study investigates the influence of post-oxidation duration on the wear performance and microstructural features of AISI 4140 steel subjected to nitrocarburizing followed by post-oxidation. For this aim, the quenched and tempered AISI 4140 samples were nitrocarburized (NC) and post-oxidized (PO) at various times (45–180 min) under low vacuum. Microstructural features were investigated using optical microscopy, scanning electron microscope (SEM), energy-dispersive X-ray spectrum analysis (EDS), X-ray diffraction (XRD) analysis, and microhardness test. Wear behavior was evaluated using a ball-on-disk tribometer. Experimental results showed that the structures consisting of nitride layer (ε-Fe2–3N) and γ′-Fe4N + iron oxide (Fe3O4) were obtained at the top surfaces of the samples. Increasing post-oxidation times resulted in a notable enhancement in the thickness of the Fe3O4 layer. The growing Fe3O4 layer has induced the closing of micro porosities for further post-oxidizing times, leading to decreased surface roughness of the samples. It was determined that the post-oxidation times have no significant effect on the hardness profiles of NC + PO samples. The highest (0.375) and lowest (0.276) mean coefficient of friction was obtained in the post-oxidation times of 150 and 180 min, respectively. The best wear rate was obtained in the post-oxidized sample for 150 min.

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Gaz Nitrasyon Yapılan 4140 Çeliğinin Minimum Kalıntı Gerilim ve Maksimum Aşınma Dayanımı İçin İşlem Parametrelerinin Optimizasyonu

TÜZÜNER¹,

METİN²,

Güler³

2022

Politeknik Dergisi

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Several surface treatments has been applied to the 4140 specimens which are exposed to frictional conditions like gears in order to increase the wear resistance and hardness. Nitration is a common method to improve the hardness of the surfaces. However, the parameters must be chosen wisely. The parameters of temperature, time, flow rate during nitration of SAE 4140 steels were optimized in this study. The ranges for the parameters are selected as 470⁰C -520⁰C -570⁰C, 7h -9h -12h and 6m 3 /h -7.5m 3 /h -9m 3 /h for temperature, time and flow rate respectively. Residual stress, hardness and wear resistance were measured for the specific experiments together with microscopic observations. The nitration process of the threaded part was completed using the optimized parameters. As a result of the study, it was observed that the maximum wear resistance and minimum residual stress values was obtained by the parameters of 470⁰C, 12h, 9m 3 /h.

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The Effect of Oxidation Process After Nitrocarburization on Tribological Properties of AISI 4140 Steel

Cited by 4 publications

References 17 publications

Nitrokarbürleme ve Son Oksidasyon Proseslerinin AISI 4140 Çeliğinin Mikroyapı ve Yüzey Özellikleri Üzerine Etkisi

Nitrokarbürleme ve Son Oksidasyon Proseslerinin AISI 4140 Çeliğinin Mikroyapı ve Yüzey Özellikleri Üzerine Etkisi

Effect of post-oxidation times in the nitrocarburizing process on the wear behavior of an AISI 4140 steel

Gaz Nitrasyon Yapılan 4140 Çeliğinin Minimum Kalıntı Gerilim ve Maksimum Aşınma Dayanımı İçin İşlem Parametrelerinin Optimizasyonu

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