Effect of Multi-Directional Hot Forging on Mechanical and Tribological Properties of Al-7Si-4Zn-3Cu Alloy

Öz

In this study, mechanical and tribological properties of multi-directional hot forged Al-7Si-4Zn-3Cu alloy at different cycles were investigated.  Multi-directional hot forging resulted in both breaking up the silicon particles and the elimination of dendritic structure of the alloy. This process increased the yield and tensile strength with percentage elongation of the alloy but decreased its hardness. The highest yield and tensile strength were obtained from the alloy forged two cycles, while the alloy forged three cycles showed a lowest hardness but the highest percentage elongation.  On the other hand, hot forged alloy exhibited higher friction coefficient and lower wear resistance than those of its homogenized state. After the wear test, smeared and delaminated friction layers were observed on the worn surface of the alloy in all test conditions. However, smearing was determined to be the main operative wear mechanism for alloy in both homogenised and hot forged states.

Anahtar Kelimeler

• Al-Si alloys,multi-directional forging,friction and wear

Çok yönlü sıcak dövme işleminin Al-7Si-4Zn-3Cu alaşımının mekanik ve tribolojik özelliklerine etkisi

Öz

Bu çalışmada farklı çevrim sayılarında çok yönlü sıcak dövme işlemine tabi tutulmuş Al-7Si-4Zn-3Cu alaşımının mekanik ve tribolojik özellikleri incelenmiştir. Çok yönlü sıcak dövme işlemi alaşımın içyapısında bulunun silisyum parçalanmasına ve dendritik yapının ortadan kalkmasına yol açmıştır. Bu işlem Al-7Si-4Zn-3Cu alaşımının akma ve çekme dayanımı ile kopma uzaması değerlerini artırmış, sertliğini ise düşürmüştür. En yüksek akma ve çekme dayanımı iki çevrim dövme uygulanmış alaşımdan, en düşük sertlik ve en yüksek kopma uzaması üç evrim uygulanmış alaşımdan elde edilmiştir. Diğer taraftan çok yönlü sıcak dövülmüş alaşım homojenize edilmiş durumuna göre daha yüksek sürtünme katsayısı ve daha düşük aşınma direnci sergilemiştir. Aşınma deneyi sonucunda alaşımların yüzeylerinde sıvanmış tabakaların oluştuğu ve soyulmaların meydana geldiği görülmüştür. Ancak sıvanmanın gerek homojenize edilmiş gerekse dövülmüş durumdaki numunelerde etken aşınma mekanizması olduğu belirlenmiştir.

Anahtar Kelimeler

• Al-Si alaşımları,çok yönlü dövme,Sürtünme ve Aşınma

Kaynakça

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