Farklı Martenzit Hacim Oranlarında Kırılma Tokluğu Değerlerinin İncelenmesi

Bu çalışmada AISI 4140 ve AISI 4340 çeliklerde martenzit hacim oranlarının sertlik ve kırılma tokluğu üzerindeki etkisi incelenmiştir. Çeliklerin ara kritik sıcaklık aralıkları belirlenerek üçer farklı sıcaklıkta su verme işlemi, ardından görüntü işleme yöntemi ile içyapı görüntüleri üzerinde her koşul için martenzit hacim oranı belirlenmiştir. Ara kritik sıcaklığın artmasıyla martenzit hacim oranları artış göstermiştir. Numunelere sertlik ve kırılma tokluğu testleri uygulanmış, martenzit miktarının artmasıyla numunelerin sertlikleri artarken kırılma tokluğunun azaldığı belirlenmiştir. AISI 4340’ın, AISI 4140’a göre daha yüksek sertlik değerlerine sahip olmasına rağmen daha düşük kırılma tokluk değerlerine sahip olduğu görülmüştür.

Anahtar Kelimeler:

AISI 4140, AISI 4340, martenzit hacim oranı, mekanik özellikler

Investigation on Fracture Toughness Values for Various Martensite Volume Fractions

In this study the effect of martensite volume fraction on hardness and fracture toughness properties of AISI 4140 and AISI 4340 steels were investigated. After determining of intercritical boundary temperatures for steels, the water quenching processes were performed at three intercritical annealing temperatures. The martensite volume fractions were determined from microstructure images for each condition by using image processing method. The martensite volume fraction increased with increasing intercritical temperature. The hardness and fracture toughness tests were conducted on the specimens. Increasing of martensite content increased the hardness values whereas decreased the fracture toughness values. Although AISI 4340 had higher hardness than AISI 4140, it had lower fracture toughness properties.

Keywords:

AISI 4140, AISI 4340, martensite volume fraction, mechanical properties,

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[1] Zare A. and Ekrami A., “Influence of martensite volume fraction on impact properties of triple phase (TP) steels”, Journal of Materials Engineering and Performance, 22(3), 823–829, (2013).
[2] Saeidi N. and Ekrami A., “Impact properties of tempered bainite-ferrite dual phase steels”, Mater. Sci. Eng. A, 527(21-22), 5575–5581, (2010).
[3] Saeidi N. and Ekrami A., “Comparison of mechanical properties of martensite/ferrite and bainite/ferrite dual phase 4340 steels”, Materials Science and Engineering A, 523(1-2), 125-129, (2009).
[4] Dalalli Isfahani A., Shafye A. and Sharifi H., “Impact and tensile properties of ferrite–martensite dual-phase steels”, Fatigue & Fracture of Engineering Materials & Structures, 38(2), 141-147, (2009).
[5] Güral A. and Tekeli S., “Microstructural characterization of intercritically annealed low alloy PM steels”, Materials and Design, 28(4), 1224-1230, (2007).
[6] Zare A. and Ekrami A., “Influence of martensite volume fraction on tensile properties of triple phase ferrite–bainite–martensite steels”, Materials Science and Engineering A, 530(1), 440-445, (2011).
[7] Fereiduni E. and Banadkouki G., “Improvement of mechanical properties in a dual-phase ferrite–martensite AISI4140 steel under tough-strong ferrite formation”. Materials and Design, 56(1), 232-240, (2014).
[8] Topçu O. and Übeyli M., “On the microstructural and mechanical characterizations of a low carbon and micro-alloyed steel”, Materials and Design, 30(8), 3274-3278, (2009).
[9] Asadi M., De Cooman B.C. and Palkowski H., “Influence of martensite volume fraction and cooling rate on the properties of thermomechanically processed dual phase steel”, Materials Science and Engineering A, 538(1), 42–52, (2012).
[10] Kumar A., Singh S. and Ray K., “Influence of bainite/martensite-content on the tensile properties of low carbon dual-phase steels”, Materials Science and Engineering A, 474(1-2), 270–282, (2008).
[11] ASTM E399-17, “Standard Test Method for Linear-Elastic Plane-Strain Fracture Toughness KIc of Metallic Materials”, ASTM International, (2017).
[12] Krauss G., “Steels: Processing, Structure and Performance”, ASM, Ohio, USA, (2006).
[13] ASTM E18-18a, “Standard Test Methods for Rockwell Hardness of Metallic Materials”, ASTM International, (2018).
[14] Ikpeseni, S., Onyekpe, B. and Ovri, H., “Influence of ıntercritical annealing temperature on mechanical properties and microstructure of 0.23%C low alloy steel”, Nigerian Journal of Technology (NIJOTECH), 34(3), 499-505, (2015).
[15] Karimi M., Kheirandish S. and Gomes U., “Study on work hardening behaviour of ferritic-bainitic dual phase steels”, 22th CBECiMat-Congresso Brasileiro de Engenharia e Ciência dos Materiais, Natal, RN, Brasil, 6226-6235, (2016).
[16] El-Bitar T., Gamil M., Mousa I. and Helmy F., “Development of carbon-Low alloy steel grades for low temperature applications”, Materials Science and Engineering A, 528(18), 6039-6044, (2011).
[17] Shibuya M., Toda Y., Sawada K., Kushima H. and Kimura K., “Effect of nickel and cobalt addition on the precipitation-strength of 15Cr ferritic steels”. Materials Science and Engineering A, 528(16-17), 5387-5393, (2011).
[18] Funni S., Koul M. and Moran A., “Evaluation of properties and microstructure as a function of tempering time at intercritical temperatures in HY-80 steel castings”. Engineering Failure Analysis, 14(5), 753-764, (2007).
[19] Zamani M., Mirzadeh H. and Ghasemi H. M., “Mechanical properties and fracture behavior of intercritically annealed AISI 4130 chromoly steel”, Materials Research Express, 5(6), 066548, (2018).
[20] Singh V.P., Gaikwad A., Khan M.Z.R. and Tiwari K., “Development of dual phase steel and determination of It's mechanical properties and comparison with low carbon steel”, International Journal of Mechanical Engineering and Technology (IJMET), 5(7), 151-159, (2014).
[21] Movaheda P., Kolahgara S., Marashia S.P.H., Pouranvarib M. and Parvina N., “The effect of intercritical heat treatment temperature on the tensile properties and work hardening behavior of ferrite–martensite dual phase steel sheets”, Materials Science and Engineering: A, 518(1–2), 1-6, (2009).
[22] Prabhu S.M., Kini U.A., Sharma S.S. and Gurumurthy B.M., “Heat treatment and mechanical characterization of dual phase (ferrite-martensite) medium carbon low alloy steels”, International Journal for Technological Research In Engineering, 3(8), 1776-1779, (2016).
[23] Sun C., Liu S., Misrac R., Li Q. and Li D., “Influence of intercritical tempering temperature on impact toughness of a quenched and tempered medium-Mn steel: Intercritical tempering versus traditional tempering”. Materials Science & Engineering A, 711(1), 484-491, (2018).
[24] Manoj M.K., Pancholi V. and Nath S.K., “Mechanical properties and fracture behavior of medium carbon dual phase steels”, International Journal of Research in Advent Technology, 2(4), 2443-249, (2014).