Al-18Si Alaşımında Döküm Kalitesi, Mikroyapı Ve Mekanik Özellikler Arası İlişkinin İncelenmesi

Bu çalışmada, primer silis ve ötektik mikroyapı morfolojisine sahip Al-18Si alaşımında döküm kalitesi, soğuma hızı ve sıvı durumda bekletme sürelerinin mikroyapı ve mekanik özelliklere etkisi incelenmiştir. 10, 15 ve 20 mm kesit kalınlığına sahip üç farklı basamağı barındıran kum kalıplar soğuma hızı farkı için kullanılmıştır. Al-18Si ötektik üstü alaşım SiC potada ergitildikten sonra üç farklı bekletme sürelerine (0, 60 ve 120 dk.) tabi tutularak kum kalıplara dökümler gerçekleştirilmiştir. Elde edilen döküm parçalarından mikroyapı, porozite incelemeleri ve çekme testleri için numuneler çıkarılmıştır. Elde edilen görüntüler üzerinde SigmaScan marka görüntü analiz programı yardımı ile incelemeler ve elde edilen datalar üzerinde de Minitab istatistiksel analiz yazılımı ile de analizler gerçekleştirilmiştir. Elde edilen tüm verilerde %18 Si içeriğine sahip Al-18Si ötektik üstü alaşımında bifilm varlığının silis oluşumunu ve buna bağlı olarak da mekanik özellikleri değiştirdiği sonucuna varılmıştır.

Anahtar Kelimeler:

Al-18Si alaşımı, Porozite, Bifilm, Mekanik özellikler, Si morfolojisi

Investigation of the Relationship Between Casting Quality, Microstructure and Mechanical Properties in Al-18Si Alloy

In this work, the effect of melt quality, cooling rate and holding time over the microstructure and mechanical properties of Al-18Si alloy was investigated. This alloy contains primer silicon and eutectic microstructure. A sand mold that has 10, 15 and 20 mm thickness that is in shape of a step mold was used. Al-18Si hypereutectic alloy was melted in SiC crucible and the casting were completed after three different holding time (0, 60 and 120 min.). Cast samples were subjected to microstructure, porosity and mechanical analysis. The images were analyzed by SigmaScan and the data were statically analyzed by Minitab. It was found that bifilms initiated silicon formation and mechanical properties were related to this mechanism

Keywords:

Al-18Si alloy, Porosity, Bifilm, Mechanical properties, Si morphology,

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