AA2024 ALAŞIMINDA SIMA YÖNTEMİ İLE TİKSOTROPİK YAPI ÜRETİMİ ÜZERİNE YENİDEN ISITMA SICAKLIĞININ ETKİSİ

Öz

Bu çalışmada, bir dövme alüminyum alaşımı olan AA2024 alaşımında gerinimin neden olduğu sıvı aktivasyonu(strain induced melt activated-SIMA) yöntemi ile yarı-katı şekillendirme için gerekli tiksotropik mikroyapıüretimi araştırılmıştır. Bu amaçla ekstrüze halde AA2024 alaşımı %20 oranında soğuk deformasyona tabitutulmuş ve takiben %30, %40 ve %50 sıvı oranına karşılık gelen yarı-katı sıcaklıklara ısıtılarak oda sıcaklığınasahip suda soğutulmuştur. Mikroyapı analizleri metalografik inceleme ve nicel ölçüm yöntemleri ile yapılmıştır.Deneysel sonuçlar, SIMA yöntemiyle AA2024 alaşımında, yarı katı şekillendirme için gerekli olan küreselşekilli tiksotropik mikroyapıların üretilebileceğini göstermiştir. Artan yarı-katı sıcaklıkla tane boyutu artarkenşekil faktöründe belirgin bir değişim gözlenmemiştir. SIMA yöntemi ile tiksotropik yapı üretimi için yarı-katısıcaklıklarda izotermal bekletmeye gerek olmadığı tespit edilmiştir.

Anahtar Kelimeler

• Yarı-katı şekillendirme, Yarı-katı sıcaklık, AA2024 alaşımı, Tiksotropik yapı, SIMA.

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