34CrNiMo6 Malzemesine Uygulanan Sıcak Şekillendirme İşleminin Dislokasyon Yoğunluğuna Etkisi

Year 2022, Volume: 8 Issue: 3, 576 - 581, 31.12.2022

Gözde Altuntaş , Bulent Bostan

Abstract

Bu çalışmada ticari olarak satın alınan 34CrNiMo6 malzemesi diğer adıyla 4340 çeliği sıcak dövme ile şekillendirilmiştir. Dövme işleminden önce ve sonra metalografik işlemler için kesilen numunelerin mikroyapıda oluşan farklılıkları taramalı elektron mikroskobu (SEM) ile gözlemlenmiştir. Oluşan farklı bölgelerdeki element oranları, enerji dağıtıcı X-ışını spektrometrisi (EDS) ile analiz edilmiştir. Malzamelerde ki dislokasyon yoğunluğunu ve kristalite boyutunu bulabilmek için X-Işını Kırınım (XRD) analizi yapılmıştır. XRD analiziyle dövme işleminin malzemede oluşturduğu kafes gerinimi de hesaplanarak ana malzemeyle karşılaştırılmıştır. Dövme işleminin malzemede oluşturduğu mekanik etkiler incelenip dinamik yeniden kristalleşmenin oluşmasıyla malzemede ki değişimler araştırılmıştır. Dinamik yeniden kristalleşme ile dislokasyon yoğunluğu arasındaki ilişki gösterilmiştir. Aynı zamanda mikro sertlik değerleri HV0.5 göre ölçülüp dislokasyon yoğunluğu ile ilişkisi incelenmiştir. Yapılan analizler sonucu ana malzemenin dislokasyon yoğunluğu dövme işlemi sonrası ortalama %50 azalmış, kristalite boyutu ise ortalama %20 artmıştır. Dövme işlemi sonrası malzemede kafes gerinim değerinin yaklaşık %30 azaldığı gözlemlenmiştir. Bu değerlerin değişimi ile sertlik değerleri arasındaki ilişki araştırılmıştır. En yüksek sertlik ana malzemede ölçülmüştür.

Keywords

34CrNiMo6, Dövme, Dislokasyon yoğunluğu

Effect of Hot Forming Process on 34CrNiMo6 Material on Dislocation Density

Abstract

In this study, commercially purchased 34CrNiMo6 material, also known as 4340 steel, was shaped by hot forging. The microstructure differences of the samples cut for metallographic processes before and after forging were observed by scanning electron microscope (SEM). Element ratios in the different regions formed were analyzed by energy dispersive X-ray spectrometry (EDS). X-Ray Diffraction (XRD) analysis was performed to find the dislocation density and crystallinity size in the materials. With XRD analysis, the lattice strain created by the forging process in the material was also calculated and compared with the raw material. The mechanical effects of the forging process on the material were examined and the changes in the material with the formation of dynamic recrystallization were investigated. The relationship between dynamic recrystallization and dislocation density is shown. At the same time, the microhardness values were measured according to HV0.5 and the relationship with the dislocation density was examined. As a result of the analysis, the dislocation density of the raw material decreased by 50% on average after forging, and the crystallite size increased by 20% on average. It was observed that the lattice strain value of the material decreased by about 30% after forging. . The relationship between the change of these values and the hardness values was investigated. The highest hardness was measured in the base material.

Keywords

34CrNiMo6, Forging, Dislocation density

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