Murat Çolak

Production of functionally graded SiC/Al-Cu-Mg composite by centrifugal casting

Abstract This study is aimed at investigating the production and wear properties of a functionally graded (FG) silicon carbide (SiC)-reinforced composite material, which was produced by stir casting followed by centrifugal casting. SiC powder (5 wt.%) was added into liquid aluminum at 750°C via stir casting, at which temperature a centrifugal force was applied to the mixture to drive the SiC particles toward the outer region of the mold. The results showed that two distinct regions formed in the cast samples after the centrifugation process. The outer region showed approximately 25% SiC particles resulting in almost SiC particle-free area in the internal region of the FG SiC-reinforced composite material. The test results showed that higher hardness and higher wear resistance could be obtained at the SiC-rich periphery of the cast FG composite material.

Melt Cleanliness Comparison of Chlorine Fluxing and Ar Degassing of Secondary Al-4Cu

The treatment of liquid aluminum prior to casting typically consists of purging gas and/or fluxes through the melt. By the use of several chemicals during these operations, several environmental problems can occur. Therefore, in this study, the melt cleanliness of Al-4Cu secondary alloy was investigated by comparing the use of argon degassing with or without chlorine fluxing. Reduced pressure test was used to assess the melt quality. Highest quality melt was obtained by Ar degassing with preheated graphite lance without the need to use any chemicals.

Investigation of Mechanical Properties of MIG Brazed DP 600 Steel Joints Using Different Working Angles

Abstract In this study, dual phase (DP 600) steel plates with a thickness of 1 mm were joined by copper-based (CuAl8) wire using gas metal arc brazing technique. Specimens were prepared in butt joint form. Brazing operations were done at four different working angles: 50°, 60°, 70°, 80° and 90°, respectively. CuAl8 wire consisted largely of copper served as the filler metal. After completing the brazing operations, the tensile properties as well as the micro- and macro-structures of the joints were analyzed in order to investigate the joinability of DP 600 steel using gas metal arc brazing technique.

Bir Konteyner Limanında Etkin Saha Planlaması için Simülasyon Tabanlı Bir Yaklaşım

Deniz tasimaciligi, cesitli ulasim cesitleri arasinda en onemli olanidir . Konteynerler, deniz tasimaciliginin bir parcasi olarak uluslararasi duzeyde nakledilmektedir. Limanlar, konteyner istifleme surecinin verimliligi acisindan kritik bir role sahiptir. Musteri memnuniyetini en ust duzeyde saglamak icin en kisa surede gelen gemilerin operasyonlarini tamamlamak gerekmektedir. Bu noktada, liman sureclerini iyilestirmek icin simulasyon bir karar destek sistemi olarak etkin bir sekilde kullanilmaktadir. Bu calismada, bir konteyner limanindaki darbogazlari gidererek en uygun istif planlamasini gerceklestirebilmek icin mevcut durum ve iki alternatif senaryo benzetim yoluyla birbirleriyle karsilastirilmistir. Gelen gemiler icin bosaltma zamaninin en aza indirgenmesi, tasiyicilarin vinclerin altindaki bekleme surelerinin kisaltilmasi ve tum ekipmanlarin adil kullanimi icin en uygun saha duzeninin belirlenmesi amaclanmistir. Boylece, enerji ve isgucu maliyetlerinin azaltilmasi planlanmaktadir.

Cu İLAVESİNİN ALÜMİNYUM ALAŞIMLARININ KOROZYON ÖZELLİKLERİNE ETKİSİNİN İNCELENMESİ

Aluminyum dokum alasimlari basta agirlik/dayanim oraninin yuksek olmasi gibi korozyon dayanimi, yuksek termal iletkenlik, iyi islenebilirlik suneklik gibi bircok avantajli ozelligi sahiptir. Bu sebeple bircok endustriyel alanda kullanilmakta ve ozellikle otomotiv sektorunde kullanimi her gecen gun daha da artmaktadir. Ancak kullanim yerine bagli olarak alasima cesitli alasim ilaveleri ile belirli ozelliklerinin artmasi beklenmektedir. Bu yonde calismalar artan ihtiyac ve kalite beklentileri dogrultusunda devam etmektedir. Al alasimina Cu ilavesi ile mekanik ozelliklerin artirmakla birlikte korozyon direncinde azalmaya neden olmaktadir. Bu calismada, ticari saflikta (%99.8 Al) Aluminyum alasimina farkli oranlarda (%2-%6-%8) Cu ilave edilerek kum kaliba dokum yontemi ile Al-Cu alasimlari uretilmistir. Calismada spektrometro ile kimyasal bilesim belirleme, yogunluk olcumleri, mikro yapi ve SEM incelemeleri ile elektrokimyasal davranislari incelenmistir. Cu ilavesinin aluminyum alasimlarinin korozyon ozelliklerine etkisi; %3.5 NaCI cozeltisi icerisinde potansiyodinamik polarizasyon yontemi ile arastirilmistir. Deneyler sonucunda, Cu ilavesi arttikca Al alasiminin korozyon direncini azaldigi tespit edilmistir.

Metot Zaman Ölçümü (MZÖ) yöntemi ile üretim süresinin iyileştirilmesi: beyaz eşya yan sanayisinde bir uygulama

Gunumuzun dinamik rekabet kosullarinda isletmeler icin maliyetlerin azaltilmasi ve uretim sureclerinde verimliligin arttirilmasi bir zorunluluk haline gelmistir. Bu baglamda uretim surelerinin onceden belirlenmesi ve mumkunse iyilestirilmesi buyuk onem tasimaktadir. Uretim surelerinin belirlenmesi icin kullanilan yontemlerden birisi de Metot Zaman Olcumu (MZO) yontemidir. MZO, el ile yapilan bir isi bu isi yapmak icin gereken temel vucut hareketleri turunden inceleyerek, hareketler icin onceden bir standart sure ortaya koyan is olcum yontemidir. Bu calismada, MZO yontemi ile beyaz esya yan sanayisinde faaliyet gosteren bir isletme icin uretim surelerinin iyilestirilmesi amaclanmistir. Bu yontem yardimiyla en kucuk hareketler bile hassas bir sekilde incelendiginden kucuk iyilestirme firsatlari yakalanarak daha verimli calisan bir uretim hatti elde edilmesi hedeflenmistir. Calisma sonucunda ele alinan urun icin iyilestirme oncesindeki uretim suresi ile iyilestirmeden sonraki uretim suresi karsilastirilarak gunluk uretim miktarinda meydana gelen artis ortaya konulmustur.

Investigation and modelling of the effects of solidification time and grain refinement on the grain size of a sand-cast Al4Cu alloy

It is well known that adding small amounts of Ti and B into aluminium casting alloys increase the fluidity, feedability, strength, fatigue resistance and pressure tightness. These occur because of Ti and B within the master alloys create heterogeneous nucleation sites by forming such intermetallic compounds as TiB2, Al3Ti and AlB2. It is also known that the solidification time is influential on the formation of final grain size of aluminium cast parts. However the combining effects of both grain refining and solidification time has not been studied properly. Therefore, in this work, the effects of the grain refining and solidification time have been investigated on a sand-cast Al-4wt%Cu alloy. To determine solidification time effect, a tests mould having different section thickness has been used.

The effects of late homogenization conditions on the Mg2Si particle size in a slow pre-heated 6063 aluminum extrusion billet

In order to investigate the effect of late homogenization conditions on the Mg2Si precipitation of 6063 grade extrusion billets are slow pre-heated to intentionally have large Mg2Si particle precipitation. Then the billets are water quenched to preserve this microstructure for late homogenizations. Finally billets are re-heated using two different furnace temperature as 450°C and 500°C at which temperatures the billet are held for 0.5 h, 1 h, 1.5 h, 2 h and 2.5 h periods and water quenched before being taken to metallographic examinations.

Fluidity Characteristics of A356 Alloy with Various Thickness Sectioned New Test Mould

Fluidity of alloys are typically carried out in a spiral test mould. Due to the variation of the results, several attempts have been made to optimise the test procedure. Pouring basin has been updated by addition of a stopper and using a defined quantity of melt to be poured. However, one of the discussed issues of the spiral test mould is its fixed size cavity where the liquid is transferred. Therefore, a mould was introduced by Campbell in which a single runner bar was used to feed different thickness sections. In this study, this mould design was used to investigate the effect of temperature (700oC, 725oC and 750oC) and modification (Ti grain refinement and Sr) on the fluidity of A356 alloy. The results were compared with the simulation (SolidCast) to optimise the characteristics of the alloy.