Sibel TÜZÜNER, Ali Baran METİN, Ebru SARALOĞLU GÜLER, Tuğçe ŞAHİN

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

Dişliler gibi sürtünme koşullarına maruz kalan 4140 çeliği numunesinin aşınma direncini ve sertliğini arttırmak için çeşitli yüzey işlemleri uygulanmıştır. Nitrasyon, yüzeylerin sertliğini iyileştirmek için yaygın bir yöntemdir. Ancak, parametreler dikkatli bir şekilde seçilmelidir. Bu çalışmada SAE 4140 çeliklerinin nitrasyonu sırasında sıcaklık, zaman, debi parametreleri optimize edilmiştir. Parametre aralıkları sıcaklık, zaman ve debi için sırasıyla 470⁰C - 520⁰C - 570⁰C, 7sa – 9sa – 12sa and 6m3/sa - 7.5m3/sa - 9m3/sa olarak seçilmiştir. Mikroskobik gözlemlerle birlikte spesifik deneyler için kalıntı gerilim, sertlik ve aşınma direnci ölçülmüştür. Optimize edilmiş parametreler kullanılarak dişli parçanın nitrasyon işlemi tamamlanmıştır.Çalışma sonucunda maksimum aşınma direnci ve minimum kalıntı gerilim değerlerinin 470⁰C, 12sa, 9m3/sa parametreleri ile elde edildiği gözlemlenmiştir.

Anahtar Kelimeler:

Gaz Nitrasyon, SAE 4140 çeliği, aşınma dayanımı, kalıntı gerilim, mikrosertlik

Optimization of Processing Parameters for Minimum Residual Stress and Maximum Wear Resistance During Gas Nitration of 4140 Steel

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 6m3/h - 7.5m3/h - 9m3/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, 9m3/h.

Keywords:

Gas Nitration, SAE 4140 steel, wear resistance, residual stress, microhardness,

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[1] Kaplan Y., Yildirim A., Aksoz S., “The Effect of Oxidation Process After Nitrocarburization on Tribological Properties of AISI 4140 Steel”, Journal of Polytechnic, 23(4): 1357-1362, (2020)
[2] Polat S., Atapek S.H., Topac H., “Microstructural Characterization on AISI 4140 and DIN 1.2344 Steels Surface Hardened by Gas Nitration”, 6th International Advanced Technologies Symposium (IATS’11), Elazig Turkey, 498-502, (2011).
[3] Mcquaid H.W., Ketcham W.J., “Practical Nitriding and Ferritic Nitrocarburizing”, Source Book on Nitriding, ASM International, Ohio USA, (2003).
[4] ASM International Handbook Committee, “Gas Nitriding of Steels”, Metals Handbook, ASM International, Vol.4 Heat Treating, 880-882, (1999).
[5] Rakhit A.K., “Nitriding Gears”, Heat Treatment of Gears, ASM International, USA, (2000).
[6] BS EN 10085, “Nitriding Steel Technical Delivery Conditions”, (2001).
[7] Peng D. Q., Kim T. H., Chung J. H., Park J. K., “Development of nitride-layer of AISI 304 austenitic stainless steel during high-temperature ammonia gas-nitriding”, Applied Surface Science, 256: 7522- 7529, (2010)
[8] Hernandez, M. H. S. M., Staia, M. H. & Puchi-Cabrera, E. S., “Evaluation of microstructure and mechanical properties of nitrided steels”, Surface and Coating Technologies, 202, 1935-1943, (2008)
[9] Yaman O., “Assesment of the Nitriding Process Parameters to Improve the Wear Resistance of Selected Steels”, M.Sc., Bogazici University Mechanical Engineering, (2009).
[10] Sree, K. R., Reddy, G. K., Aishwarya, K., Devi, E. N., & Subbiah, R., “New Insights of Wear Behavior Analysis on Low Temperature Treated AISI 253MA Stainless Steel Material by Gas Nitriding Process”, E3S Web of Conferences ICMED (Vol. 184, p. 01003), (2020).
[11] Pinar M.A., Firat K., “Optimization of Surface Roughness Performance in the Turning of AISI 4140 Steel with Multi Directional Cutting Tool”, Journal of Polytechnic, 19(4): 491-498, (2016)
[12] Wang S., Wang Y., Liu C., & Mazumder J., “In-Situ Monitoring on Micro-Hardness of Laser Molten Zone on AISI4140 Steel by Spectral Analysis”, Scientific Reports, 10(1): 1-12, (2020)
[13] SAE J 1268, “Standard Alloy H Steels”, (2010).
[14] Porter D.A., Easterling K.E., “Phase Transformations in Metals and Alloys 4th Edition”, CRC Press, USA, (2021).
[15] Korkmaz. K, “Effects of The White Layer Formed by Gas Nitriding on The Wear Behavior of Nitriding Steel”, M.Sc., Gebze Technical University Department of Materials Science and Engineering, (2020).
[16] Holm, T., Sproge, L., “Nitriding and Nitrocarburizing”, Furnace Atmospheres 3, AGA, SWE, (1996).
[17] Topcu S., “Determination of Wear Behavior of Plasma Nitrided Steels Under Different Conditions”, M.Sc., Uludag University Institute of Science Department of Mechanical Engineering, (2010).
[18] Gecu R., “Investigation of Residual Stress and Hardness Changes in Gas Nitrided 31CrMoV9 Steel by Indentation Method”, M.Sc., Istanbul Technical University Metallurgical and Materials Engineering Department Materials Engineering Program, (2014).
[19] Subasi M., Karatas C., “Investigation of the Effect of Different Hardnesses Obtained in AISI 4140 Steel on Residual Stress”, Journal of Polytechnic, 14(4): 289-295, (2011)
[20] Asan N.O., “Improving the Surface Properties with Nitrogen Diffusion to the Steel Surface”, M.Sc., Yıldız Technical University Metallurgical and Materials Engineering, (2004).