Usibor 1500 çeliğinin ostenitleme sürelerine bağlı olarak çekme özelliklerinin incelenmesi
Date
2020-08-10
Authors
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Publisher
Bursa Uludağ Üniversitesi
Abstract
Sıcak şekillendirme işlemi, ultra yüksek dayanımlı çeliklere soğuk şekillendirme proseslerinde verilemeyecek kompleks şekillerin verilmesi amacıyla son dönemlerde yaygın bir şekilde kullanılan teknolojidir. Sıcak şekillendirme prosesi ile birlikte daha hafif, daha dayanıklı ve daha doğru geometriye sahip parçaların üretilebilmesi mümkün olmaktadır. Bu çalışma için, sıcak şekillendirme prosesine uygun olan ultra yüksek dayanımlı Usibor 1500 çeliği seçilmiştir. Çalışma kapsamında, Usibor 1500 çeliğinin ostenitleme sürelerine bağlı olarak çekme özelliklerinde meydana gelen değişimler incelenmiştir. Deney numuneleri 910 °C'da farklı sürelerde (30 saniye, 90 saniye, 3 dakika, 5 dakika ve 10 dakika) ostenitlenmesi için bekletilmiştir. Müteakiben deney numuneleri suda su verilerek soğutulmuştur. Ardından deney numunelerinin sertlikleri ölçülmüş, mikroyapıları incelenmiş ve çekme testine tabi tutulmuştur. Sertlik ölçümleri sonucu ostenitleme süresi arttıkça sertlikte de artış görülmüştür. Başlangıçta 198 HV civarında olan Usibor 1500 çeliğinin sertliği, 5 dakika ostenitleme süresi ile birlikte 500 HV seviyesine ulaşmıştır. Çekme testi sonucunda ostenitleme süresi arttıkça mukavemette de artış görülmüştür. Çekme mukavemeti 617 MPa civarında olan Usibor 1500 çeliğinin ısıl işlem sonrası çekme mukavemetinin beklenildiği gibi 1500 MPa seviyelerine ulaştığı gözlemlenmiştir
Hot stamping process is the technology that has been widely used recently in order to give complex shapes that cannot be given to ultra high strength steels in cold forming processes. With the hot stamping process, it is possible to produce lighter, more durable and more accurate geometry parts. For this study, ultra high strength Usibor 1500 steel, which is suitable for hot stamping process, has been chosen. Within the scope of the study, changes in tensile properties of Usibor 1500 steel depending on the austenitization times were investigated. The test samples were kept at 910 °C for austenitization at different times (30 seconds, 90 seconds, 3 minutes, 5 minutes and 10 minutes). Subsequently, the test samples were cooled by giving water in water. After, the hardness of the test samples were measured, their microstructures were examined and they were subjected to tensile testing. As the waiting time increased as a result of hardness measurements, an increase in hardness was observed. The hardness of the Usibor 1500 steel, which was originally around 198 HV, reached 500 HV with a 5 minutes austenitization time. As a result of the tensile test, as the austenitization time increased, the strength increased. The tensile strength of Usibor 1500 steel, which has a tensile strength of around 617 MPa, has been observed to reach 1500 MPa levels as expected after heat treatment
Hot stamping process is the technology that has been widely used recently in order to give complex shapes that cannot be given to ultra high strength steels in cold forming processes. With the hot stamping process, it is possible to produce lighter, more durable and more accurate geometry parts. For this study, ultra high strength Usibor 1500 steel, which is suitable for hot stamping process, has been chosen. Within the scope of the study, changes in tensile properties of Usibor 1500 steel depending on the austenitization times were investigated. The test samples were kept at 910 °C for austenitization at different times (30 seconds, 90 seconds, 3 minutes, 5 minutes and 10 minutes). Subsequently, the test samples were cooled by giving water in water. After, the hardness of the test samples were measured, their microstructures were examined and they were subjected to tensile testing. As the waiting time increased as a result of hardness measurements, an increase in hardness was observed. The hardness of the Usibor 1500 steel, which was originally around 198 HV, reached 500 HV with a 5 minutes austenitization time. As a result of the tensile test, as the austenitization time increased, the strength increased. The tensile strength of Usibor 1500 steel, which has a tensile strength of around 617 MPa, has been observed to reach 1500 MPa levels as expected after heat treatment
Description
Keywords
Ultra yüksek mukavemetli çelikler, Usibor 1500, Sıcak şekillendirme, Ultra-high stength steels, Usibor 1500, Hot stamping
Citation
Baburoğlu, T. (2020). Usibor 1500 çeliğinin ostenitleme sürelerine bağlı olarak çekme özelliklerinin incelenmesi. Yayınlanmamış yüksek lisans tezi. Bursa Uludağ Üninersitesi Fen Bilimleri Enstitüsü.