Friction Stir Welding (FSW) is a solid-state welding process used for welding similar and dissimilar materials. FSW is especially suitable to join sheet Al alloys, and this technique allows different material couples to be welded continuously. In this study, 1050 Al alloys and commercially pure Cu were produced at three different tool rotation speeds (630, 1330, 2440 rpm) and three different tool traverse speeds (20, 30, 50 mm/min) with four different tool position (0, 1, 1.5, 2 mm) by friction stir welding. The influence of the welding parameters on the microstructure and mechanical properties of the joints was investigated. Tensile and bending tests and microhardness measurements were used to determine the mechanical properties. The microstructures of the weld zone were investigated by optical microscope and scanning electron microscope (SEM) and were analyzed in an energy dispersed spectrometer (EDS). Intermetallic phases were detected based on the X-ray diffraction (XRD) analysis results that evaluated the formation of phases in the weld zone. When the welding performance of the friction stir welded butt joints was evaluated, the maximum value obtained was 89.55% with a 1330 rpm tool rotational speed, 20 mm/min traverse speed and a 1 mm tool position configuration. The higher tensile strength is attributed to the dispersion strengthening of the fine Cu particles distributed over the Al material in the stir zone region.

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In welding technology, joining processes of different materials, which have dissimilar crystal structures are difficult. Welding of different materials becomes very important to reduce costs. Furthermore, the friction welding method is processed in lower temperature than the melting temperature. Especially, this is a big advantage to overcome difficulties that occur in the heat affected zone during usage of conventional methods.In this study, the weldability of AISI 304 stainless steel and AISI 1040 carbon steel by friction welding is studied. During the welding process, temperature variations in the welding zones were measured with an infrared temperature measurement device. After welding of the samples, tensile and hardness experiments were carried out. For metallographic investigations, optical microscope and scanning electron microscope (SEM) pictures were taken. Energy dispersive spectroscopy (EDS) analysis was carried out for composition investigations on welding and heat affected zones. As a result, these two steels could be joined by friction welding for industrial usage.

The optimization of the friction welding parameters through experimental studies does not only cause loss of time and materials but also increases the cost. In this study, an Artificial Neural Network (ANN) model is developed for the analysis of the correlation between the friction welding parameters and tensile strength of both AISI 316 austenitic-stainless steel and Ck 45 steel. The input parameters of the model are friction time, friction pressure and upset pressure while tensile strength is the output. Experimental data are used to train and test the neural network. A good correlation was obtained between the experimental values and the ANN model prediction (R 2 = 0.9711). By using this model, the number of experiments to obtain optimal parameters of friction welding and number of tensile tests could be minimized. K e y w o r d s : friction welding, AISI 316 stainless steel, Ck 45 steel, mechanical properties, Artificial Neural Network (ANN)

This study has arisen from the necessity to manufacture an impeller and a shaft pair of a water pump from two different types of steels. The impeller has to have resistant to corrosion and the shaft has to have magnetic permeability property. It is deemed suitable to use the AISI 316 austenitic stainless steel performing high resistance corrosion for the impeller and Ck 45 carbon steel with magnetic permeability property for the shaft. The joining of AISI 316 and Ck 45 steels has been achieved by using the friction welding method. After welding process, the tests of tensile and micro hardness were applied, the microstructures were observed, and composition of elements was found in the welding zone. As optimum welding parameters, 100 MPa of friction pressure, 10 s of friction time, 200 MPa of upset pressure and 20 s of upset time were determined in 3000 rev/min rotation speed.