Publication: Semı solıd slurry productıon for thıxocastıng
Abstract
Yarı katı üretimi, metalin yarı-katı bölgesinde şekillendirilmesi ve bu sayede net şeklini kazanmasıdır. Sıvı metalin ısı içeriğinden daha düşük ısıya sahip olması, döküm kalıbını daha iyi doldurması ve sıvı metalden daha yüksek vizkoziteye sahip olmaları nedeniyle birçok alanda yararlar sağlamaktadırlar. Bu çalışmada ilk amaç, ucuz ve iki farklı üretim yöntemi olan modif edilmiş Strain Induced Metal Activated (SIMA) ve soğutma eğrisi kullanılarak Al-Ni esaslı yarı katı alaşım üretip incelemek ve iki metodun sonuçlarını karşılaştırmaktır. İkinci amaç ise, yarı katı küresel yapılı malzeme oluşturmak için, ötektik altı ve ötektik üstü Al-Ni esaslı alaşım kullanıp yapısal özellikler üzerindeki etkilerini incelemektir. Yapılan deneylere göre, Al-Ni alaşımının dökümü için ergitme fırını, K tipi termocuple ve kokil kalıbı kullanıldı. Aynı döküm işlemi soğutma eğrisi kullanarak da uygulandı. Alaşımdaki nikel yüzdesini incelemek için, sıcaklığa bağlı sıvı yüzdesi hesaplandı. SIMA prosesinin gerekliliklerinden olan soğuk deformasyon işlemi tüm alaşımlar için aynı pres makinesinde farklı yüklerde uygulandı. Deformasyon işleminden sonra incelen alaşımlara 650 ºC’de kalınlığa bağlı olarak 27-33 dakika arasında ısıl işlem uygulandı. Daha sonra bu alaşımlar, numune hazırlama yöntemleri olan kesme, bakalit alma, zımparalama, parlatma ve dağlama işlemleri uygulanarak mikroskop altında inceleme yapıldı. Sonuç olarak, her iki üretim yöntemi kullanılarak elde edilen alaşımlarda olumlu etkiler görülmüştür. Ötektik altı nikel kullanılarak üretilen alaşımlar sertken ötektik üstü nikel alaşımları daha serttir. alaşımı, SIMA, soğutma eğrisi, yarı katı
Semi solid processing is a metal forming that carried out in mushy zone to provide gaining net shape. Net shape characteristics such as lower heat content than liquid metal, better mold filling and higher viscosity than liquid metal offer several benefits for various applications. In this study, the first aim is to produce and investigate Al-Ni base semi-solid alloy structure using two cheap different routes, modified Strain Induced Metal Activated (SIMA) and cooling slope (CS), and compare their results. Second aim is to cast the metal by adding hyper-hypo eutectic nickel to investigate the effect of the nickel composition on structural properties. According to experiments, Al-Ni alloy casting carried out and for casting, melting furnace, K type thermocouple and permanent mould were utilized. Same casting was realized with cooling slope. To examine the nickel percentage in alloy, liquid fraction according to temperature was calculated. As the requirements of SIMA process, casting alloys were cold deformed in different forces by using same press machine. After pressing thickness reduced alloys were subjected to heat treatment at 650ºC between 27-33 minutes depending on thickness. Then, sample preparation methods; cutting, mounting, grinding, polishing and etching were implemented to be able to investigate microstructure under microscope. In conclusion, positive effects could be seen for both alloys from both production processes. Also, hypo and hyper eutectic nickel effects could be seen as the alloy with hypo-eutectic nickel was hard wheras the alloy with hyper-eutectic nickel was harder. October, 2016 Zeynep ÖZDEMİR Key Words: Al-Ni alloy, cooling slope, semi solid, SIMA.
Semi solid processing is a metal forming that carried out in mushy zone to provide gaining net shape. Net shape characteristics such as lower heat content than liquid metal, better mold filling and higher viscosity than liquid metal offer several benefits for various applications. In this study, the first aim is to produce and investigate Al-Ni base semi-solid alloy structure using two cheap different routes, modified Strain Induced Metal Activated (SIMA) and cooling slope (CS), and compare their results. Second aim is to cast the metal by adding hyper-hypo eutectic nickel to investigate the effect of the nickel composition on structural properties. According to experiments, Al-Ni alloy casting carried out and for casting, melting furnace, K type thermocouple and permanent mould were utilized. Same casting was realized with cooling slope. To examine the nickel percentage in alloy, liquid fraction according to temperature was calculated. As the requirements of SIMA process, casting alloys were cold deformed in different forces by using same press machine. After pressing thickness reduced alloys were subjected to heat treatment at 650ºC between 27-33 minutes depending on thickness. Then, sample preparation methods; cutting, mounting, grinding, polishing and etching were implemented to be able to investigate microstructure under microscope. In conclusion, positive effects could be seen for both alloys from both production processes. Also, hypo and hyper eutectic nickel effects could be seen as the alloy with hypo-eutectic nickel was hard wheras the alloy with hyper-eutectic nickel was harder. October, 2016 Zeynep ÖZDEMİR Key Words: Al-Ni alloy, cooling slope, semi solid, SIMA.