Haitham Mohammed Ibrahim Al-Zuhairi

This research is an experimental comparison study to show the influence of mold type casting on mechanical properties. The study considers the aluminum alloy of a gasoline engine piston with nanoparticles alumina Al2O3 size 25 nm manufactured in two types of molds. Sand mold and cast-iron mold were selected to cast the aluminum composite components. A systematic comparative study of tensile strength and hardness properties of cast aluminum components is made on sand and metal molds production. The nano powder can add to enhance the mechanical properties must not exceed 4 % for metal and sand mold casting. According to data for hardness, adding nano alumina powder has minimal impact on metal mold casting, but it significantly improves sand casting. From a financial standpoint, metal casting provides higher economic values for making piston aluminum castings. The hardness rises as the alumina content does in two molds as compared to the obtained specimen. It demonstrates that the highest hardness occurs at 4 % alumina in the sand-casting mold and at 6 % alumina in the metal. When the compositions of the casting materials are the same, a comparison of the fracture morphology between sand and mold casting reveals more ductile fractures for metal molds compared to brittle fractures in sand cast by large silicon separation grains because of higher grain growth in sand casting by longer solidification time. The same is seen in mold casting, which exhibits reduced ductility due to the alumina nanoparticles' dispersion strengthening process in the aluminum matrix. This arises as a result of nano alumina dispersion acting as barriers to dislocation motions in the aluminum matrix, enhancing strength but reducing ductility.

The function of the axle drive shaft is to transfer the engine torque from the gearbox or differential gear to the wheels. It must also endure for all dynamic loads resulted from variations in angle or length during driving from contact the vehicle tire with road. Most problems with the axle drive shaft manifest themselves in the form of knocking noises when driving around tight corners, accelerating, or when the suspension is being compressed and extended where the drive shaft becomes weakened and more subject to stress failure due to dynamic torsion, tensile, shear, and compression. This work consists of effect of heat treatment type applied to the steels CK45 on the resulted behavior of the fatigue and toughness and study of these heat treatments on the microstructure and micro-hardness across the specimens depth. Where this heat treatable alloy usually used in drive-shafts in vehicles which exposed to a dynamic loads and the goal is to investigate the best relation between heat treatment and the service conditions. However, microstructural characterization and microhardness measurements revealed that the shaft belongs to medium carbon steel contains ferrite and pearlite, measuring the toughness for four heat treatments to obtain the best case and measuring the fatigue life of quenching case has better life compared to other cases. The oil quenching gives best toughness value of 30 Kj/m² and the worst value obtained for as received one giving 7 Kj/m² and the maximum fatigue life under stress of 375 MPa belonged to oil quenching treatment and it was 75000 cycles to failure while the as-received alloy reported 2000 cycles at failure. The S-N curve of the four cases based on Basquin formula with correlation factor (R²) close to one. And the water quenching steel alloy recorded higher curve component to other cases.