Borlu Çeliklere Uygulanan Temperleme ve Kriyojenik İşlemin Mekanik Özelliklere Etkisinin İncelenmesi

Öz

Borlu çelikler, aşınma direnci yüksek ve sertleşebilme kabiliyeti ile ön plana çıkmış bir çelik grubudur. Bu çalışma da 33MnCrB5-2 borlu çeliğe sıcak dövme işlemi uygulanarak şekillendirilmiştir. Sıcak dövme işlemi sonrası malzemelerin mikroyapı incelemeleri ve mekanik testleri yapılmıştır. Bir grup malzemeye -80 °C de 2 saat kriyojenik işlem uygulanmıştır. Ardından farklı bir grup malzeme 890 °C östenitlenip su verilmiş ardından 400 °C’de 90 dakika temperleme işlemi uygulanmıştır. Son grup malzeme de temperleme ısıl işlemi sonrası -80 °C de 2 saat kriyojenik işlem uygulanmıştır. Kriyojenik işlem ve temperleme ısıl işlemi uygulanan numunelerin mekanik olarak sertlik ve aşınma testi yapılmıştır. Mikroyapı analizleri tarama elektron mikroskobu (SEM) ve optik mikroskop yardımı ile incelenmiştir. Enerji-dağıtıcı X-ışını spektrometresi (EDS) ile ısıl işlemler sonrası mikroyapıdaki farklı bölgelerden element dağılımları analiz edilmiştir. X-ışını difraksiyonu ile malzemelerin tane boyutları hesaplanmıştır. Sonuçlar temperleme sonrası kriyojenik işlem uygulanan numunelerin sertlik değerinin ve aşınma dayanımının diğer numunelere kıyasla daha yüksek değerler verdiğini göstermiştir.

Anahtar Kelimeler

• Anahtar kelimeler: Borlu çelikler
• kriyojenik işlem
• temperleme

Investigation of the Effect of Tempering and Cryogenic Treatment on Mechanical Properties of Boron Steels

Abstract

Boron steels are a group of steels that stand out with their high wear resistance and hardenability. In this study, 33MnCrB5-2 boron steel was shaped by applying hot forging process. After the hot forging process, the microstructure examinations and mechanical tests of the materials were carried out. A group of materials was cryogenically treated at -80 °C for 2 hours. Then, a different group of materials was austenitized at 890 °C and quenched, and then tempered at 400 °C for 90 minutes. In the last group of materials, after tempering heat treatment, cryogenic treatment was applied at -80 °C for 2 hours. Hardness and abrasion tests were carried out on the samples that were subjected to cryogenic treatment and tempering heat treatment. Microstructure analyzes were examined with the help of scanning electron microscope (SEM) and optical microscope. Element distributions from different regions in the microstructure were analyzed with energy-dispersive X-ray spectrometry (EDS). The crystallite size of the materials were calculated by X-ray diffraction. The results showed that the hardness value and wear resistance of the samples that were cryogenically treated after tempering gave higher values compared to the other samples.

Keywords

• Boron steels
• cryogenic treatment
• tempering

Kaynakça

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