EVALUATION OF SURFACE ROUGHNESS AND MATERIAL REMOVAL RATE IN ELECTRICAL DISCHARGE MACHINING OF AL-ALLOY WITH 10%SIC

Aluminum-based metallic matrix compounds are widely used in industrial and aircraft manufacturing due to their advanced characteristics, such as toughness and high strength resistance to weight ratio, etc. Silicon carbide is an important industrial ceramic and it is the fourth hardest ceramic after diamond, boron nitride, and boron carbide. Owing to its low fracture toughness, it is difficult to machine silicon carbide using traditional machining processes. Electrical discharge machine can machine such materials irrespective of their hardness. Aluminum alloy 6061 and 10% SiC based-metal matrix composite were used as a workpiece that was produced by stir casting. In the experimental investigation, pulse current Pc (10, 20, and 30 A), pulse on (Pon) duration (100, 150, and 200 ?sec), and pulse off (Poff) duration (6, 12, and 24 ?sec) were treated as the input variables. The output responses were surface roughness (SR) and material removal rate (MRR). The best value for surface roughness (Ra) reached (1.032 µm) at Pc (10 A), Pon duration (100 ?sec) and Poff (15 ?sec). Also, the best result for the productivity of the process (MRR) reached (69.49 × 10-3 g/min) at Pc (30 A) Pon, (200 ?sec) and (6 ?sec) Poff. Therefore, the experimental outcomes were optimized for surface roughnes and material removal rate by adding 10% SiC to aluminum alloy 6061. ABSTRAK: Sebatian matrik logam berasaskan aluminium telah digunakan secara meluas dalam industri pembuatan dan pesawat kerana ciri-cirinya yang canggih, seperti ketahanan dan daya rintangan yang tinggi kepada nisbah berat, dan lain-lain. Silikon karbida adalah seramik industri yang penting dan ia merupakan seramik keempat terkuat setelah berlian, boron nitrida dan boron karbida. Disebabkan ketahanan frakturnya yang rendah, adalah sukar bagi menghasilkan mesin silikon karbida menggunakan proses pemesinan tradisional. Mesin pelepasan elektrik mampu menghasilkan mesin menggunakan bahan tersebut tanpa mengira kekerasan. Aloi aluminium 6061 dan komposit matrik logam berasaskan SiC 10% telah digunakan sebagai bahan kerja yang terhasil melalui tuangan kacauan. Melalui penyelidikan eksperimen, detik arus Pc (10, 20, dan 30 A), detik hadir (Pon) berdurasi (100, 150, dan 200 ?sec), dan detik henti (Poff) berdurasi (6, 12, dan 24 ?sec) dirawat sebagai pemboleh ubah input. Respon pengeluaran adalah kekasaran permukaan (SR) dan kadar penyingkiran bahan (MRR). Nilai terbaik bagi kekasaran permukaan (Ra) telah mencapai (1.032 µm) pada Pc (10 A), berdurasi Pon (100 ?sec) dan Poff (15 ?sec). Tambahan, hasil terbaik bagi proses produktiviti (MRR) mencapai (69.49 × 10-3 g/min) pada Pc (30 A) Pon, (200 ?sec) dan (6 ?sec) Poff. Oleh itu, hasil eksperimen dioptimumkan bagi permukaan kasar dan kadar penyingkiran bahan dengan tambahan 10% SiC ke aloi aluminium 6061.

Design and development of aluminum alloy 6061-T6 pressure vessel liner for aerospace applications: A technical brief

This work mainly focuses on designing a novel aluminum alloy 6061-T6 pressure vessel liner intended for use in launch vehicles. Fabrication of custom-made welding fixtures for the assembly of liner parts, namely two hemispherical domes and end boss, is illustrated. The parts of the liner are joined using the cold metal transfer welding process, and the welding trials are performed to arrive at an optimized parametric range. The metallurgical characterization of weld joint reveals the existence of dendritic structures (equiaxed and columnar). Microhardness of base and weld metal was 70 and 65 HV, respectively. The tensile strength of base and weld metal was 290 and 197 MPa, respectively, yielding a joint efficiency of 68%. Finite-element analysis of a uniaxial tensile test was performed to predict the tensile strength and location of the fracture in base and weld metal. The experimental and predicted tensile test results were found to be in good agreement.

EFFECT OF PRE-HEATING ON THE MECHANICAL PROPERTIES OF FRICTION STIR WELDING FOR 6061 ALUMINUM ALLOY

Friction stir welding (FSW) process is a solid-state joining invented via the Welding Institute in 1991 at a great rate emerging as an application by fusion welding for joining different alloys. The wrought aluminum alloy 6061 is heat treatable and possesses a high corrosion resistance. This alloy has been used in a wide range of applications, like arenas gymnasiums and trains bodies. Aluminum alloy 6061 cannot be easily welded by the conventional fusion welding process because of the cracks that make the mechanical of welding joint very weak. In FSW, many parameters effect on its welding process. In the present research, the pre-heating effect on the aluminum 6061 sheet at 100°C and 150°C was studied. This heat has to be given for obtaining a defect-free as well as quality joint. Result manifested that the welding without pre-heating the parent metal at a (1120 r.p.m) rotational speed and a (30 mm/min) welding speed gave the best result of the ultimate tensile strength (236 N/mm2).

Development of Elastoplastic-Damage Model of AlFeSi Phase for Aluminum Alloy 6061

Material properties affect the surface finishing in ultra-precision diamond cutting (UPDC), especially for aluminum alloy 6061 (Al6061) in which the cutting-induced temperature rise generates different types of precipitates on the machined surface. The precipitates generation not only changes the material properties but also induces imperfections on the generated surface, therefore increasing surface roughness for Al6061 in UPDC. To investigate precipitate effect so as to make a more precise control for the surface quality of the diamond turned Al6061, it is necessary to confirm the compositions and material properties of the precipitates. Previous studies have indicated that the major precipitate that induces scratch marks on the diamond turned Al6061 is an AlFeSi phase with the composition of Al86.1Fe8.3Si5.6. Therefore, in this paper, to study the material properties of the AlFeSi phase and its influences on ultra-precision machining of Al6061, an elastoplastic-damage model is proposed to build an elastoplastic constitutive model and a damage failure constitutive model of Al86.1Fe8.3Si5.6. By integrating finite element (FE) simulation and JMatPro, an efficient method is proposed to confirm the physical and thermophysical properties, temperature-phase transition characteristics, as well as the stress–strain curves of Al86.1Fe8.3Si5.6. Based on the developed elastoplastic-damage parameters of Al86.1Fe8.3Si5.6, FE simulations of the scratch test for Al86.1Fe8.3Si5.6 are conducted to verify the developed elastoplastic-damage model. Al86.1Fe8.3Si5.6 is prepared and scratch test experiments are carried out to compare with the simulation results, which indicated that, the simulation results agree well with those from scratch tests and the deviation of the scratch force in X-axis direction is less than 6.5%.