Aluminum alloys are the subject of increasing interest in the automotive, as well as aircraft industries. Concerning the assembly, welding was extensively applied in the car industry. Nevertheless, welding defects generated during the process result in reduction in strength of both the weld; and heat affected zone which could limit its applications. Electron beam welding (EBW) has unique advantages over other traditional fusion welding methods due to its high-energy density, deep penetration, large depth-to-width ratio and the resulting very small heat affected zone. Optimization of EB welded joint of 2219 Al-alloy, from the yield strength, hardness and bead geometry point of view, is the topic of this study. Taguchi methodology with grey relation analysis has been applied to find the optimal welding parameters for welding of a sheet of the mentioned aluminum alloy with electron beam. The optimal welding parameters have been selected and verified experimentally.

Aiming to reduce the weight of components, thus allowing a profit in terms of energy saving, automotive industry as well as aircraft industry extensively uses aluminum alloys. The most widely used joining technology in aircraft industry is riveting, while welding seems to be used in the car industry in the case of aluminum alloys. However, welding technology is characterized by many defects, such as gas porosity; oxide inclusions; solidification cracking (hot tearing); and reduced strength in both the weld and the heat affected zones which could limit its development. Many techniques are used for aluminum alloys welding, among them is electron beam welding (EBW), which has unique advantages over other traditional fusion welding methods due to high-energy density, deep penetration, large depth-to-width ratio, and small heat affected zone. The welding parameters that yield to optimal weld joint have been previously obtained. These optimal parameters were validated by welding a specimen using these parameters. To evaluate this optimal weld joint, complete, microstructural observations and characterization have been carried out using scanning electron microscopy, optical microscopy, and energy dispersive X-ray analysis. This evaluation leads to description and quantification of the solidification process within this weld joint.

This experimental study was conducted to investigate the optimum combination of properties between ductility and toughness from one hand and strength and hardness from the other hand of a commercial grade of light duty spring steel DIN 50Cr3 having a chemical composition of (0.25 % C, 0.8%Cr , 0.79%Mn , 0.2% Si). A heat treatment process by quenching in both oil or water followed by tempering cycles at different temperatures for various tempering times was adopted. The proper austenitization temperature was found to be 870 C. The structure after quenching reveals the formation of martensite with limited amount of retained austenite. Tempering was performed at different temperatures from 250 to 550 C for prolonged times ranging from 1hr up to 3 hr. It was found that oil quenching provides sensibly higher elastic properties than water quenching particularly in the low tempering temperature range. More ever, by increasing the tempering temperature and time ultimate tensile strength, hardness were gradually decreased while ductility remarkably improved. The resultant microstructure after tempering was characterized by a tempered martensitic structure with simple and complex dispersed carbides. Optimum elastic properties were delivered out of this steel after tempering at 450 C for 1hr.