Hot tear-melt quality relationship in 3xxx aluminium alloys

Corrosion resistance, formability and high strength is few of the major properties that makes aluminium alloys preferred choice of material for extrusion or deep drawing processes. Particularly, buildings, windows, doors are main application areas and it is growing. Twin roll casting method is used to produce such materials. One of the common problems faced in this method is called hot tearing. The effect of alloying elements is the reason for this defect. As a result, segregation causes tear and decrease process efficiency. The economic impact is immanent. Thus, it is aimed to study the hot tear tendency of 3xxx series aluminium alloys and the effect of alloying elements will be investigated in this work

Production of functionally graded AlB2/Al-4%Mg composite by centrifugal casting

In this study, production of functionally graded AlB2 reinforced Al-4%Mg composite has been investigated. In-situ high-aspect-ratio flake AlB2 reinforcement was obtained by the addition of boron oxide to the liquid Al-Mg at 1400 °C. It has been observed that there were two distinct regions without a smooth grading: one is rich of and the other is poor of AlB2. The results showed that the highest AlB2 content has been found to be around 10% in external zones, whereas the lowest AlB2 content has been observed to be 0.02% in the internal zones.  Additionally,   results showed that, depending on the increase in the reinforcement phase in external zones, up to 20 % increase in the hardness of the composite has been achieved

The Effect of Electromagnetic Stirring on the Microstructural and Mechanical Properties of A356 Casting Alloy

Aluminium casting alloys, having high strength, high corrosion resistance, high thermal conductivity and low density, are widely used in automotive and many other industrial areas. However, to meet new demands from the industry for superior properties the conventional cast aluminium alloys still need further improvements. In recent years, the desire of new processes to improve the properties of aluminium casting alloys resulted in new researches into high performance and low cost processes such as semi solid forming. Semi-solid forming processes are widely used for Al-Si casting alloys having large eutectic proportions, high fluidity and good castability such as the A356 alloy. In this process the morphology of the primary alpha phase and the formation of thixotropic material structure play an important role. There are several techniques for producing thixotropic materials through degenerating the dendrites and the most effective of them is electromagnetic stirring. In this study, the effect of electromagnetic stirring on the microstructural and mechanical properties during solidification of A356 alloy which has been produced with electromagnetic stirring has been investigated

A356 Döküm Alaşımında Elektromanyetik Karıştırmanın Mikroyapı ve Mekanik Özelliklere Etkisi

Alüminyum döküm alaşımları, yüksek mukavemet, yüksek korozyon dayanımı, yüksek termal iletkenlik ve düşük yoğunluk gibi üstün özelliklerinden dolayı başta otomotiv olmak üzere birçok endüstriyel alanlarda yaygınca kullanılmaktadır. Ancak gelişen teknolojiyle birlikte alüminyum dökümlerinin kalitesinin artırılmasına ihtiyaç duyulmaktadır. Alüminyum dökümlerinin kalitesinin artırılmasına yönelik yeni proses arayışları, son yıllarda yarı katı şekillendirme tekniği gibi üstün mukavemet özellikleri ve düşük maliyet ile ön plana çıkan yeni proseslerin araştırılmasına yol açmıştır. Yarı katı şekillendirme prosesi, çoğunlukla yüksek miktarda Al-Si ötektik fazı içerdikleri için çok iyi akışkanlık ve dökülebilirliğe sahip olan A356 gibi döküm alaşımlarına uygulanır. Bu proseste primer alfa fazının morfolojisi ve tiksotropik özellikteki malzeme üretimi önemli rol oynamaktadır. Tiksotropik özelliğe sahip malzeme üretmek yani katılaşma sırasında dentritik yapının bozulmasını sağlamak için birçok yöntem vardır ve bu yöntemler arasında en etkilisi elektromanyetik karıştırma tekniğidir. Yapılan bu çalışmada hazırlanan deneysel amaçlı elektromanyetik karıştırma düzeneğiyle A356 döküm alaşımına katılaşma esnasında uygulanan farklı şiddetlerdeki karıştırmanın mikroyapı ve mekanik özelliklerine etkilerinin araştırılması amaçlanmıştır. Uygulanan elektromanyetik karıştırmayla dentrit kollarının kırılması ve bu prosesin malzeme özelliklerine etkileri incelenmiştir

Influence of Different Cross Sections on Fluidity Characteristics of A356

Fluidity of cast metals are typically measured by the length of metal that is stopped by the solidification where the filling is carried out at a constant cross sectional mold cavity. In this work, a sand mold geometry with different section thicknesses were used to measure the fluidity characteristics of A356 alloy at various casting temperatures (700, 725, 750 A degrees C) with and without modifications. It was found that Ti modification had no significant effect on fluidity. On the other hand, the highest fluidity was achieved by Sr modification even at low pouring temperatures. The results were compared with simulation software (SolidCast), and critical fraction of liquid (CFL) was determined

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

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 (700 degrees C, 725 degrees C and 750 degrees C) 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

INVESTIGATION OF THE EFFECT OF HOLDING TIME AND MELT STIRRING ON THE GRAIN REFINEMENT OF AN A206 ALLOY

Effects of melt stirring and holding time were studied with an Al-4.5 \% of mass fractions of Cu (A206) alloy. The optimum level of a grain refiner was determined in conjunction with both continuously stirred and non-stirred melts during the holding time. Results showed that a mass fraction of a Ti addition of as low as 0.03 \% was sufficient to obtain the 82 mu m average grain size, while a Ti addition exceeding the mass fraction of 0.03 \% showed no significant effect on the grain size of castings. The grain refinement tends to fade with a long holding time in a non-stirred liquid. The results also showed that an effective grain refinement of the A206 alloy can be achieved with a long holding time as long as the liquid alloy is continually stirred