Recycling Al-Si Alloy by Semisolid Material Dragged during Continuous-Casting Strip Processing

Recycled Al–Si (9.2%) alloy contaminated with Fe (0.3%), Pb (3.1%) and Sn (11.4 %) was cast and poured at 650 oC, approximately 50 oC above the liquidus line. A cooling slope was used to obtain a semisolid material that feeds a ceramic nozzle designed to function as a good contact area for solidification and improve the quality of strip casting. The internally cooled material rolls in soluble oil (1 oil / 9 water) at a rate of 0.2 l/s and works as a heat exchanger which drags the metallic slurry puddle generated at the roll surface at a speed of 0.12 m/s. This forms a metallic strip with a thickness of 2 mm and a width varying from approximately 45 mm to 60 mm. The cooling system of the rolls, combined with four springs placed at the housing screw, prevented adhering of the metallic strip during production at a pressure of approximately 450 N. Cracks were observed on the strip surfaces; however, these defects did not interrupt the continuous flow of the solidified strip during manufacturing. The strip’s poor surface quality could be related to the Pb and Sn contamination as well as cold cracks due to the low pouring temperature. Al-Si eutectics positioned at a grain boundary of α-Al globular structures, as well as the presence of a Sn phase, resulted in a metallic strip with a yield stress, maximum stress and elongation of 94.5 MPa, 100.2 MPa and 1.6%, respectively.

Jaya Algorithm for Optimization of Cooling Slope Casting Process Parameters

This study proposed the Jaya algorithm to estimate an improved value of billet performance through the cooling casting process. Jaya algorithm is a recent evolution-based algorithm that simulates using stochastic behaviour. The algorithm concept is the solution obtained for a given problem should move towards the best solution and should avoid the worst solution. This algorithm requires only the common control parameters and does not require any algorithm specific control parameters. To the best our knowledge, Jaya algorithm is not yet been used computational approach for optimization practice, particularly in the Cooling casting process. Three Cooling slope parameters process that influences the billet performance measurements, a maximum degree of sphericity and minimum grain size are pouring temperature, slanting angle, and travelling distance. The results show that the Jaya algorithm gave a better optimal solution for the maximum degree of sphericity and minimum particle size than experimental data.

Estimation of The IMC Layer Thickness of Friction-Stir-Welded Aluminum/Copper Lap Joints By Using Temperature Simulation

Many studies demonstrated the suitability of Friction Stir Welding (FSW) for joining dissimilar materials. Especially the combination of aluminum and copper is of high interest for many applications. Intermetallic compounds (IMC) forming during FSW due to interdiffusion and the thickness of the IMC layers strongly influence the joint properties, e.g. the joint strength or the thermal and electrical conductivity. Therefore, it is important to predict the IMC layer thickness to tailor the joint properties to the individual application. For this purpose, a thermal-pseudo-mechanical model was built to simulate the temperature field during FSW of aluminum EN AW-1050 and copper CW008A in lap joint configuration. The simulated temperatures as well as the heat inputs corresponded well with experimental data for a wide range of parameter settings. In order to estimate the IMC layer thickness, the simulated temperatures close to the interface of the materials were used. Two approaches for calculating the layer thicknesses were compared. In the first approach, the thickness is calculated based on the peak temperature lasting for several seconds at the interfacial area. This approach was applied for constant feed rates, while the second approach also accounted for the cooling slope and could therefore be used for different feed rates.

Studi Sifat Mekanik Re-casting Ingot A356 Produksi PT. INALUM Menggunakan Cooling Slope

Alumunium (Al) A356 yang memiliki sifat mekanis yang baik telah secara luas dipergunakan di bidang teknik. Namun tidak dapat dihindari proses pengecoran ulang bahan Al termasuk A356 akan menurunkan sifat mekanis. Usaha perbaikan dan meminimalkan pengaruh tersebut telah dilakukan dengan berbagai cara diantaranya menggunakan cooling slope. Penelitian ini bertujuan untuk mengetahui sifat mekanis dan mikrostruktur pengecoran ulang aluminium A356 menggunakan metode cooling slope. Temperature penuangan 680oC dengan kemiringan 30˚, 45˚, 60˚ dan panjang pelat 80 cm dipasang sesaat sebelum cairan memasuki cetakan permanen. Observasi mikrostruktur menggunakan optical microscope (OM) memperlihatkan mikrostruktur tersusun dari primari Al dan partikel silikon. Variasi kemiringan pelat pada saat penuangan juga memengaruhi kehalusan mikrostruktur. Hasil pengujian kekerasan tertinggi 62 HB diperoleh pada variasi sudut tuang 30˚. Pengujian ketahanan aus dilakukan pada kondisi kering tanpa pelumas menggunakan metode pin on disc di mana diperoleh laju keausan paling rendah pada bahan dengan sudut kemiringan 30o dan tertinggi pada sudut 60o. Pada bagian lain, pengujian tarik dilakukan pada suhu kamar dengan hasil memperlihatkan kekuatan tarik maksimum 157 MPa untuk sampel dengan penuangan 30o.