Farklı ısıl işlemlerin takım çeliklerinin yorulma mukavemeti üzerine etkileri

İstenilen kullanım amacına bağlı olarak çeliklerin mekanik özelliklerini iyileştirmek için çeşitli ısıl işlemler uygulanmaktadır. Bu çalışmada, bir GS 550 banyosunda H13 sıcak iş takım çeliğinin ısıl işlemle yorulma dayanımının değişimi araştırılmıştır. Birinci ön ısıtma, ikinci ön ısıtma, sertleştirme ve ikinci sertleştirme olmak üzere dört farklı ısıl işlem uygulanarak incelenmiştir. Her numune grubu, ısıl işlemden sonra oda sıcaklığında döner eğmeli yorulma testine tabi tutulmuştur. Isıl işlem görmemiş numunelerin yorulma dayanımı 470 MPa olarak belirlenmiştir. İkinci sertleştirme yapılmış temperlenmemiş numunelerin (1. Grup) yorulma mukavemeti 610 MPa'ya yükselmiştir. Sertleştirmeden sonra ikinci bir ısıl işlem olarak 550ºC'de iki saat tavlanan numunelerin (2. Grup) yorulma dayanımı 630 MPa olarak ölçülmüştür. 550ºC'de iki saat ve 610ºC'de iki saat tavlama olan üçüncü ısıl işlemin uygulanmasıyla numunelerin (3. Grup) yorulma dayanımı 720 MPa olarak bulunmuştur. Dördüncü ısıl işleme tabi tutulmuş ve sertleştirmeyi takiben 550ºC'de iki saat ve ardından 635ºC'de iki saat temperlenmiş numunelerin (4. Grup) yorulma mukavemeti 710 MPa olarak belirlenmiştir. Uygulanan tüm ısıl işlemlerin H13 sıcak iş takım çeliğinin yorulma mukavemetini olumlu etkilediği gözlemlenmiştir. Tüm ısıl işlemler artan yorulma mukavemeti ile sonuçlanırken, en yüksek yorulma mukavemeti, ilk ön ısıtma ve su verme işleminden sonra çift tavlama ısıl işlemi (550 °C ve 610 °C iki saat) ile elde edilmiştir.

Anahtar Kelimeler:

H13 sıcak iş takım çeliği, Isıl işlem, Yorulma

The effects of different heat treatments on the fatigue strength of tool steels

Various heat treatments are applied to improve the mechanical properties of steels depending on the intended use. In this study, the variation of fatigue strength of H13 hot work tool steel with heat treatment in a GS 550 bath was investigated. It was investigated by applying four different heat treatments as first preheating, second preheating, hardening and second hardening. Each batch of samples was subjected to rotating bending fatigue test at room temperature after heat treatment. The fatigue strength of the untreated samples was determined as 470 MPa. The fatigue strength of the second hardened untempered samples (Group 1) increased to 610 MPa. The fatigue strength of the samples (Group 2), which were annealed for two hours at 550ºC as a second heat treatment after hardening, was measured as 630 MPa. The fatigue strength of the samples (Group 3) was found to be 720 MPa by applying the third heat treatment, which was annealing at 550ºC for two hours and at 610ºC for two hours. The fatigue strength of the samples (Group 4), which were subjected to the fourth heat treatment and tempered for two hours at 550ºC and then at 635ºC for two hours after hardening, was determined as 710 MPa. It has been observed that all applied heat treatments positively affect the fatigue strength of H13 hot work tool steel. While all heat treatments resulted in increased fatigue strength, the highest fatigue strength was obtained with double annealing heat treatment (550 °C and 610 °C two hours) after initial preheating and quenching.

Keywords:

H13 hot-work tool steel, Heat treatment, Fatigue,

PDF

___

Akata E., Altinbalik T., & Can Y. (2004). Three point application in single tooth bending fatigue test for evaluation of gear blank manufacturing method. International Journal of Fatigue, 26, 785–789. https://doi.org/10.1016/j.ijfatigue.2003.11.003
Bannantine J. A., Comer J. J., & Handrock J. L. (1990). Fundamentals of Metal Fatigue Analysis (1st Ed.) , Prentice Hall, New Jersey, USA.
Barraua O., Bohera C., Grasb R., & Rezai-Aria F. (2003). Analysis of the friction and wear behavior of hot work tool steel for forging. Wear, 255, 1444–1454. https://doi.org/10.1016/S0043-1648(03)00280-1
Çöl M., & Koç F. G. (2015). Effect of homogenization heat treatment on toughness and wear resistance of plastic mold steel. Materials Testing, 57, 11-12, 942–946. https://doi.org/10.3139/120.110807
Fares M. L., Moussa A., Khelfaoui Y., & Khettache A. (2012). An investigation into the effects of conventional heat treatments on mechanical characteristics of new hot working tool steel. IOP Conference Series Materials Science and Engineering, 28, 012 – 042. https://doi.org/10.1088/1757-899X/28/1/012042
Guanghua Y., Xinmin H., Yanqing W., & Xingguo Q. (2010). Effects of heat treatment on mechanical properties of H13 steel. Metal Science and Heat Treatment, 52, 7–8, 393 – 395. https://doi.org/10.1007/s11041-010-9288-4
İynen O., Ekşi A. K., Özdemir M., & Akyıldız H. K. (2021). Experimental and numerical investigation of cutting forces during turning of cylindrical AISI 4340 steel specimens. Materials Testing, 63, 5, 402 – 410. https://doi.org/10.1515/mt-2020-0069
Kumar R., Behera R. K., & Sen S. (2015). Effect of Tempering temperature and time on strength and hardness of ductile cast iron. IOP Conf. Series: Materials Science and Engineering, 75 https://doi.org/10.1088/1757-899X/75/1/012015
Lin M., Zhao X., Han L., Liu Q., & Gu J. (2016). Microstructural evolution and carbide precipitation in a heat-treated H13 hot work mold steel. Metallography Microstructure and Analysis, 5, 520–527. https://doi.org/10.1007/s13632-016-0318-5
Özdemir M., & Dilipak H. (2020). Numerically modeling spring back and spring go amounts and bending deformations of Cr-Mo alloyed sheet. Materials Testing, 62(12), 1265–1272. https://doi.org/10.3139/120.111613
Perssona A., Hogmarkb S., & Bergström J. ( 2004). Simulation and evaluation of thermal fatigue cracking of hot work tool steels, International Journal of Fatigue, 26, 1095–1107. https://doi.org/10.1016/j.ijfatigue.2004.03.005
Roux S. L., Medjedoub F., Dour G., & Rézaï-Aria F. (2013). Role of heat‐flux density and mechanical loading on the microscopic heat‐checking of high temperature tool steels under thermal fatigue experiments. International Journal of Fatigue, 51, 15–25. https://doi.org/10.1016/j.ijfatigue.2013.02.004
Shi Y.J., Wu X.-C., Li J.-W., & Min N. (2017). Tempering stability of Fe-Cr-Mo-W-V hot forging die steels. International Journal of Minerals Metallurgy and Materials, 24(10), 1145–1157. https://doi.org/ 10.1007/s12613-017-1505-3
Sjöström J., & Bergström J. (2004). Thermal fatigue testing of chromium martensitic hot-work tool steel after different austenitizing treatments. Journal of Material Processing Technology, 153, 1089–1096. https://doi.org/10.1016/j.jmatprotec.2004.04.158
Smith W. F. (1993). Structure and Properties of Engineering Alloys (2nd Ed.), McGraw-Hill Science/Engineering/Math, New York, USA.
Souki I., Delagnes D., & Lours P. (2011). Influence of heat treatment on the fracture toughness and crack propagation in 5% Cr martensitic steel. Procedia Engineering, 10, 631–637. https://doi.org/10.1016/j.proeng.2011.04.105
Sun Y., Hanaki S., Yamashita M., Uchida H., & Tsujii H. (2004). Fatigue behavior and fractography of laser-processed hot work tool steel. Vacuum, 73, 655 – 660. https://doi.org/10.1016/j.vacuum.2003.12.161.
Wilzer J., Kuepferle J., Weber S., &Theisen W. (2014). Influence of alloying elements, heat treatment, and temperature on the thermal conductivity of heat treatable steels. Steel Research International, 86, 1234–1241. https://doi.org/10.1002/srin.201400294
Velay V., Bernhart G., & Penazzi L. (2006). Cyclic behavior modeling of a tempered martensitic hot work tool steel. International Journal of Plasticity, 22,459–496. https://doi.org/10.1016/j.ijplas.2005.03.007