SR katkılı A360 alüminyum alaşımlarında termomekanik işlemin mekanik özelliklere etkisinin incelenmesi
Küçük Resim Yok
Tarih
2024
Yazarlar
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Yayıncı
Tekirdağ Namık Kemal Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Bu tez çalışmasında kum kalıba döküm yöntemi ile üretilmiş A360 alaşımına, mikroyapı ve mekanik özellikleri üzerindeki etkisini incelemek üzere %ağ. 0.0144, 0.0441 ve 0.0767 oranlarında stronsiyum ilave edilmiştir. Daha sonra numunelere ön yaşlandırma işlemi yapılarak ısıl işlemin etkisi de görülmüştür. Bu işlemler sonucunda en yüksek çekme mukavemetine sahip numunelere termomekanik işlemler uygulanmıştır. Bu işlemin ilk aşamasında numunelere %10, 20, 30, 40, 50, 60, 70 miktarlarında soğuk deformasyon uygulanmıştır. Deformasyon sonrası çekme mukavemeti en yüksek numunelere yeniden yaşlandırma işlemi uygulanmıştır. Ön yaşlandırma işlemleri 160, 180, 200 oC sıcaklık ve 2, 4, 6 saat sürelerle gerçekleştirilirken yeniden yaşlandırma işlemleri 160, 180, 200, 280, 320° sıcaklık ve 2, 4, 6 saat sürelerde uygulanmıştır. Tüm işlem adımlarında mekanik özellikleri belirlemek üzere numunelere sertlik ve çekme testi uygulanmıştır. Ayrıca ön yaşlandırma işlemi uygulanan numunelere yorulma testi yapılmıştır. Mikroyapı çalışmaları, optik mikroskop, (SEM), (EDS) ve (XRD) ile gerçekleştirilmiştir. Sonuçlar incelendiğinde stronsiyum elementinin ötektik silisyum üzerinde önemli etkisi olduğu görülmüştür. Isıl işlemsiz ve ısıl işlemli stronsiyum içeren numunelerde en yüksek çekme mukavemeti ve sertlik değeri %ağ. 0.0144 oranında stronsiyum içeren numunelerde görülmüştür. Soğuk deformasyona uğrayan numunelerde en yüksek çekme mukavemeti %70 oranında deforme edilen numunelerde görülmüştür. %50, 60 ve 70 miktarlarında deforme edilen numunelere yeniden yaşlandırma işlemi uygulanmıştır. Yeniden yaşlandırma sonucunda numunelerin mukavemet değerleri düşerken süneklik değerleri yükselmiştir.
In this thesis study, strontium was added to the A360 alloy produced by sand mold casting method at the rates of 0.0144, 0.0441 and 0.0767 wt% to examine its effect on the microstructure and mechanical properties. Then, the samples were pre-aged and the effect of the heat treatment was observed. As a result of these processes, thermomechanical processes were applied to the samples with the highest tensile strength. In the first stage of this process, 10, 20, 30, 40, 50, 60, 70% cold deformation was applied to the samples. Re-aging was applied to the samples with the highest tensile strength after deformation. While pre-aging processes were carried out at 160, 180, 200 °C and 2, 4, 6 hours, re-aging processes were carried out at 160, 180, 200, 280, 320 °C and 2, 4, 6 hours. Hardness and tensile tests were applied to the samples to determine mechanical properties at all processing steps. In addition, fatigue tests were performed on the samples that were pre-aged and as-cast. Microstructural studies were carried out by optical microscope, (SEM), (EDS), and (XRD). When the results were examined, it was seen that the strontium element had a significant effect on eutectic silicon. he highest tensile strength and hardness values of the samples containing strontium without heat treatment and with heat treatment were observed in the samples containing 0.0144 wt% strontium. The highest tensile strength of the cold deformed specimens was observed in the specimens deformed by 70%. Re-aging was applied to the samples deformed by 50, 60 and 70%. As a result of re-aging, the strength values of the samples decreased while the ductility values increased.
In this thesis study, strontium was added to the A360 alloy produced by sand mold casting method at the rates of 0.0144, 0.0441 and 0.0767 wt% to examine its effect on the microstructure and mechanical properties. Then, the samples were pre-aged and the effect of the heat treatment was observed. As a result of these processes, thermomechanical processes were applied to the samples with the highest tensile strength. In the first stage of this process, 10, 20, 30, 40, 50, 60, 70% cold deformation was applied to the samples. Re-aging was applied to the samples with the highest tensile strength after deformation. While pre-aging processes were carried out at 160, 180, 200 °C and 2, 4, 6 hours, re-aging processes were carried out at 160, 180, 200, 280, 320 °C and 2, 4, 6 hours. Hardness and tensile tests were applied to the samples to determine mechanical properties at all processing steps. In addition, fatigue tests were performed on the samples that were pre-aged and as-cast. Microstructural studies were carried out by optical microscope, (SEM), (EDS), and (XRD). When the results were examined, it was seen that the strontium element had a significant effect on eutectic silicon. he highest tensile strength and hardness values of the samples containing strontium without heat treatment and with heat treatment were observed in the samples containing 0.0144 wt% strontium. The highest tensile strength of the cold deformed specimens was observed in the specimens deformed by 70%. Re-aging was applied to the samples deformed by 50, 60 and 70%. As a result of re-aging, the strength values of the samples decreased while the ductility values increased.
Açıklama
Fen Bilimleri Enstitüsü, Makine Mühendisliği Ana Bilim Dalı
Anahtar Kelimeler
Makine Mühendisliği, Mechanical Engineering
