Ahmed Shash

Synthesis and Characterization of New Cast A356(Al2O3)P Metal Matrix Nano-Composites

The present investigation studies the processing of A356 Al-Si alloy containing up to 5% vol.-% nano-sized al2 o3 particles having size less than 500 nm. Composites were prepared using semi-solid casting route. To evaluate the results the alloys were further characterised by various metallurgical and mechanical characterization methods. The results showed that introducing nano-particles into semi-solid slurries promises to be a successful route for producing a new generation of cast metal matrix nano-composites (MMNCs). The nano-composites showed high strength values associated with superior ductility, low porosity content, high corrosion resistance, and improved electrical conductivity compared to the alloy without particles addition under the same casting conditions.Copyright

Mechanical Properties and Wear Resistance of Semisolid Cast Al2O3 Nano Reinforced Hypo and Hyper-eutectic Al–Si Composites

The present investigation studies the prospects of using nanoparticles as reinforcement ceramic powders to gain improved performance of hypo and hyper eutectic Al cast alloys. A series of castings were prepared using A356 and A390 as the matrix alloy and alumina nano-powder in 40 nm size as the reinforcement. The nanoparticles were added to the molten slurries with stirring with different fraction ratios ranging from (0, 1, 2 and 4 wt%) in the mushy zone using a constant stirring time for one minute. To evaluate the results, the alloys were further characterized by various tribological and mechanical characterization methods. The results showed higher strength values with improved ductility compared to the monolithic alloys under the same casting conditions. The results also showed improvement in the wear resistance of the nano-reinforced alloys. The scanning electron microscopy of the fracture surface and the wear surface revealed the presence of nanoparticles in the interdendritic spacing and this confirmed with EDX analysis of these particles. The data obtained from the experimental work in this study together with previous published work by the authors were statistically analyzed using analysis of variance (ANOVA) to define the significant factors on both ultimate tensile strength and ductility and their level of confidence, using the orthogonal array L8. Response surface methodology (RSM) was used to build a model relating the type of matrix and nanoparticles addition to the ultimate tensile strength (UTS). The results have shown that the percent of the nanoparticles additions have a significant effect on the tensile properties of the alloys.

The Effect of Process Parameters on the Mechanical Properties of A356 Al-Alloy/ZrO2 Nanocomposite

In this study the effect of zirconia (ZrO2) nanoparticles (40 nm) in reinforcing A356 aluminum alloys as a base metal matrix were investigated. Zirconia nanopowders were stirred in the A356 matrix with different fraction ratios ranging from (0, 1, 2, 3, 5%) by weight at variable stirring speeds ranging from (270, 800, 1500, 2150 r.p.m) at a mushy zone (600°C) and liquid state (700°C) using a constant stirring time for one minute. The microstructure revealed the change of grains from dendritic to spherical shape with increasing stirring speed. The Scanning Electron Microscopy of the fractured surface revealed the presence of nanoparticles at the interdendritic spacing of the fracture surface and was confirmed with EDX analysis of these particles.The results of the study showed that the mechanical properties (strength, elongation and hardness) using ZrO2 as reinforcements were increased at the following parameters: 1500 r.p.m stirring speed in semi-solid state (600oC) and adding 3 wt.% of ZrO2.

Effect of Friction Stir Welding Parameters on the Peak Temperature and the Mechanical Properties of Aluminum Alloy 5083-O

In the present investigation, a 3D transient heat transfer model is developed to simulate the thermal distribution of aluminum alloy 5083-O friction stir welded by using Abaqus software. A 6 mm AA5083-O plates were friction stir welded at different conditions; two tools with tapered smooth and cylindrical threaded pin profiles, and 50, 100, 160 mm/min welding speeds at a constant rotational speed of 400 rpm. The temperature was measured using an infrared thermal image camera during the welding process at each operation condition. The measured temperature by IR camera was compared with temperatures obtained using the Abaqus. The welded joints were checked by visual inspection, macrostructure and microstructure evolution, in addition to tensile strength and hardness profiling. The welding speed and tool pin profile variations have a small effect on the peak temperature of the welded joints. The defect free welded joints were obtained at 50, 100, 160 mm/min welding speeds using a threaded tool pin profile. The tensile strength values obtained by using a threaded tool pin profile at all welding speeds are better than those obtained by using a tapered tool pin profile where the best one is at 50 mm/min welding speed. In terms of hardness results, the threaded tool pin profile gives better results at all welding speeds than the tapered tool pin profile.

Options for Nanoreinforced Cast Al–Si Alloys with TiO 2 Nanoparticles

This study presents a new concept of refining and enhancing the properties of cast aluminium alloys by adding nanoparticles. In this work the effect of adding titanium dioxide (TiO2) nano-particles (40 nm) to the aluminum cast alloy A356 as a base metal matrix was investigated. Titanium dioxide nano-powders were stirred into the A356 matrix with different fraction ratios ranging from (0, 1, 2, 3, 4, 5 %) by weight at variable stirring speeds ranging from (270, 800, 1500, 2150 rpm) in both the semisolid (600 °C) and liquid state (700 °C) using a constant stirring time of one minute. The cast microstructure exhibited change of grains from dendritic to spherical shape when increasing stirring speed. The fracture surface showed the presence of nanoparticles at the interdendritic spacing of the fracture surface and was confirmed with EDXS analysis of these particles. The results of the study showed that the mechanical properties (strength, elongation and hardness) for the nanoreinforced castings using TiO2 were enhanced for the castings made in the semi-solid state (600 °C) with 3 % weight% of TiO2 at 1500 rpm stirring speed.

Influence of Al2O3 Nano-dispersions on Mechanical and Wear Resistance Properties of Semisolid Cast A356 Al Alloy

The present investigation studies the prospects of using nanoparticles as reinforcement ceramic powders to gain improved performance of A356 Al cast alloy. Alumina nano-powder of 40 nm size was stirred into the A356 matrix with different fraction ratios ranging from (0, 1, 2 and 4 wt%) in a mushy zone (600 °C) using a constant stirring time for one minute. To evaluate the results, the alloys were further characterized by various tribological and mechanical characterization methods. The results showed higher strength values with improved ductility when compared to the monolithic alloy under the same casting conditions. Also, the wear resistance has been positively enhanced as the amount of the Al2O3 nano-particles addition increases from 1 to 4 wt% leading to a decrease in the weight loss ranging from 5.5 to 4.0 mg, respectively. The Scanning Electron Microscopy of the fracture surface and the wear surface revealed the presence of nanoparticles at the interdendritic space of the fracture surface and was confirmed with an EDX analysis of these particles.

APPLICATION OF SHORT FIBERS REINFORCED COMPOSITES IN POWER TRANSMISSION COUPLING

IN THIS STUDY THE USE OF SHORT GLASS, CARBON AND HYBRID GLASS-CARBON FIBERS REINFORCED POLYMERIC COMPOSITES IN POWER TRANSMISSION COUPLING IS INVESTIGATED. THE PRESENTED WORK IS GENERALIZED TO THER-MOPLASTIC AND THERMOSET POLYMERIC MATRIX COMPOSITES. THE EFFECTS OF THE CONSTITUENTS WEIGHT PERCENTAGES, AND AVERAGE FIBERS LENGTH ON THE COMPOSITE TENSILE STRENGTH AND MODULUS ARE STUDIED USING THE TAGUCHI DESIGN OF EXPERIMENTS METHOD. A NEW APPROACH OF FINITE ELEMENT ANALYSIS IS INTRODUCED TO MODEL THE EFFECT OF THE HYBRID FIBERS RANDOM DISTRIBUTION AND AVERAGE FIBERS LENGTH AMONG THE VOLUME OF THE MATRIX. EACH FIBER IS SIMULATED INDEPENDENTLY IN THE MODEL AS A THREE DIMENSIONAL TRUSS ELEMENT EMBEDDED IN THE MATRIX. THE FEA MODEL IS APPLIED ON THE TENSILE SPECIMEN AND THEN ON THE POWER TRANSMISSION COUPLING SIMULATION. FINALLY, THE COUPLING SUGGESTED FEA MODELING RESULTS ARE COMPARED WITH THE CONVENTIONAL ISOTROPIC SIMULATION.

Effect of Tempcore Processing on Mitigating Problems of Tramp Elements in Low C Steel Produced from Recycled Material

The effect of tramp elements in the steel was intensively studied. It was found that the solubility of tramp elements decreased as the temperature decreased under normal cooling conditions. The tramp elements (Cu, Pb, and Sn) diffused toward the grain boundaries, and intermetallic compounds or rich phases which have low melting points were formed, causing reduction in ductility and failure during the bending test. Rebars with Cu content which were left to air cooling after the last step showed drop in elongation, up to 32%. On contrast, the samples with high percentage of tramp elements (Cu, Pb, and Sn) in the billet, which were rolled and subjected to Tempcore process, did not show drop in elongation or failure in bending test (especially for rebar with diameter less than 32 mm) ; however, copper must be less than 0.35 mass% to prevent the precipitation of Cu-rich zones of critical size in 32 mm. When quenching was applied, the tramp elements remained in the interstitial supersaturated solid solution positions inside the grains and would not have the chance to diffuse and form precipitates, hindering the copper precipitates from reaching the critical size necessary for impairing the properties. This would hinder the occurrence of the harmful effect of the tramp elements on the elongation or the hot shortness after rolling.

Semi-automated Gating System Design with Optimum Gate and Overflow Positions for Aluminum HPDC

Die casters usually carry out a die casting test before producing new castings. At the die-casting test stage, the runner and gate parts are always repeatedly corrected, which lead to a lengthened processing time and increased processing cost. In this study, a computer software was developed to calculate the gating system design with optimum gate and overflow positions for cold chamber High Pressure Die Casting (HPDC) die design by getting the part dimensions and choosing the suitable machine from a pre-defined database in the software. A design of experiment is used to formulate the objective function of the gate and overflow optimum position. At the end of this paper, a case study was developed as part of the software validation. The results show that the developed software can calculate the gating system design and eliminate the correction in the test stage.

Improvement of Mechanical Properties and Structure Modifications of Low Carbon Steel by Inoculations with Nano-Size Silicon Nitride

AISI 1020 steel is considered to be one of the most applicable structural steels, in particular in the cold drawn form. Heating of this grade of steel prior to AC1 must have been applied to spheroidize the lamellar cementite, and consequently enhances the cold formability character of the steel. Si3N4 nanoinoculation of this grade of steel has been used in this study, where it is added to the molten steel, in order to avoid the high cost long term heat treatment process prior to cold deformation process. Optical microscopy and SEM have been used to evaluate the morphology of cementite after nanoinoculation process with Si3N4. Tensile properties of nanoinoculated steels have been investigated. Finally, wear adhesive resistance of investigated samples has been evaluated. The obtained results showed a great enhancement in the mechanical properties, strength, ductility and adhesive wear resistance, as a result of the nucleation of cementite into a new spheroidal phase and grain refinement by Si3N4 inoculation and allow usage of AISI 1020 steels inoculated by nanoinoculant Si3N4 in further technological applications.