Effect of Compression Time on Microstructure and Hardness of A356 Fabricated via Thixoforming

Yıl 2021, Cilt: 13 Sayı: 3, 9 - 14, 31.12.2021

Bekir Yavuzer Dursun Özyürek

https://doi.org/10.29137/umagd.1038092

Öz

This study investigates the effect of compression time and milling on microstructure and hardness of A356 alloy produced by thixoforming, which is one of the semi-solid forming methods. As a result of the microstructure studies, it was determined that there was an increase in the globalization amount of the grains and a decrease in the grain sizes depending on the compression period. The highest globularization rate was measured in the sample, which did not milled and had 2 minutes compression time in the thixoforming process. As a result of the hardness measurements taken from different positions of the samples, it was observed that the hardness values of the samples decreased from the outer surface. The highest hardness value was obtained from the samples produced by compressing for 2 minutes and not milled. In addition, EDS analysis results showed that there is more silicon in the grain boundaries than in the grain.

Anahtar Kelimeler

A356, Thixoforming, Microstructure, Hardness

Tikso Şekillendirme ile Üretilen A356 Alaşımında Sıkıştırma Süresinin Mikro Yapı ve Sertlik Üzerine Etkisi

Öz

Bu çalışmada yarı-katı şekillendirme yöntemlerinden biri olan tikso şekillendirme ile üretilen A356 alaşımında, sıkıştırma süresinin ve ön şekillendirilen tozların deformasyonunun, alaşımın mikro yapı özelliklerine etkisi incelenmiştir. Mikro yapı incelemeleri sonucunda sıkıştırma süresine bağlı olarak tanelerin küreselleşme miktarında artış olduğu, tane boyutlarında ise düşüş meydana geldiği belirlenmiştir. En yüksek küresellik oranı, öğütme işlemi uygulanmamış ve tikso şekillendirme işleminde 2 dakika sıkıştırma süresi kullanılmış olan numunede ölçülmüştür. Numunelerin farklı bölgelerinden alınan sertlik ölçümleri sonucunda, dış yüzeyden itibaren numunelerin sertlik değerlerinde azalma olduğu görülmüştür. En yüksek sertlik değeri öğütme işlemi uygulanmamış ve 2 dakika sıkıştırılarak üretilmiş numunelerden elde edilmiştir. Ayrıca EDS analizi sonuçlarında tane sınırlarında, tane içlerine göre daha fazla silisyum bulunduğu belirlenmiştir.

Anahtar Kelimeler

A356, Tikso şekillendirme, Mikro yapı, Sertlik

Kaynakça

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