Friction welding is becoming a viable replacement of conventional joining methods. Continuous Drive Friction Welding (CDFW) is a type of friction welding used to join rods, tubes and similar shapes. Usually, the process contains a friction stage and a forging stage and the process parameters would be ticked accordingly. AA6061 is an Mg and Si aluminum alloy that is widely used in many industries. This research investigates the effect of friction time on the mechanical properties of AA6061 joints made with CDFW and the relation to the microstructure of the material and thermal profiles. It was found that AA6061 does not require a forging stage where solid joints are obtained without forging and did not fracture within the welding zones. Also, it was concluded that the process parameters are to be tailored in a way that produces a specific type of grain structure within the welding areas.

In the present work, different heat treatments like hardening with different cooling rates followed by tempering at different temperatures have been performed. The material used in this study is carbon steel of 0.27% C and 0.84% Mn. Samples of as-rolled steel were subjected to different heat treatment processes. The steel was heated to the austenitizing temperature of 870°C for 2hrs followed by water quenching, oil quenching, air and furnace cooling. Water and oil quenched samples were subjected to tempering for one hour at temperatures of 250°C, 350°C, 450°C and 550°C. Tensile and impact tests were carried out for as rolled and heat-treated steel. Results show that the heat treated steel revealed an excellent combination of tensile strength and impact strength, which is suitable for structural applications. Optical metallographic investigation was carried out for all samples compared with the as rolled steel. The heat treatment revealed remarkable changes in steel morphology and mechanical properties.

The effects of precipitated phases during aging treatment on the properties of the Cu-Be alloy have been extensively studied. In this study, the effect of cold rolling on the precipitated phases of the Cu-Be alloy compared with non-deformed alloy during isothermal and low heating rate aging of 20C/min have been investigated. Hardness changes, differential scanning calorimetry (DSC), dilatation analysis, and transmission electron microscopy (TEM) were used in this study. Hardening and contraction were strongly increased at an early aging time for the cold rolled Cu-Be alloy. In addition, the DSC curves revealed an exothermic peak from the γ΄΄ phase. This peak increased and shifted to lower aging time by increasing the cold rolling reduction. In addition, the hardness remarkably increased at lower aging temperatures for the cold rolled specimens. The contraction from the dilatation curves and the exothermic peaks shifted to lower aging temperatures in cold rolled specimens. The hardening of Cu-Be alloy is believed to be from the γ΄ phase, and the contraction and the first exothermic peak in DSC curves from γ΄΄ phase. TEM observations are in a good agreement with the above explanation and strongly revealed that γ΄΄ and γ΄ phases were highly accelerated by the effect of cold rolling

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