Effect of friction stir welding process parameters on mechanical properties and microsturture of dissimilar aluminum to copper joint

The present research is aimed to study on effect of friction stir welding process parameters on aluminum alloy 1100-H18 to pure copper joints. The effect of welding parameters¡ including rotational speed¡ feed rate and pin offset on the tensile strength of samples investigated and were optimized by response surface method. In order to verify the results of tensile tests¡ metallographic evaluation¡ microhardness and X-ray diffraction tests were conducted. Microstructural evaluation of the weld samples revealed that the interfacial regions are characterized by mixture layers of aluminum and copper. High Vickers microhardness values were measured at the joint interfaces¡ which corresponded with the intermetallic compounds. The diffractograms of the X-Ray Diffraction analysis showed small peaks for intermetallics in the welds. Welds produced with low heat input did not have intermetallics formed at the joint interface¡ whereas welds produced by highest heat input¡ have the highest content of intermetallics. As well as to determine the maximum temperature in weld nugget¡ FEM analysis have been conducted and formation temperature of intermetallic components was determined. To evaluate the effect of welding parameters¡ including rotational¡ linear speed and tool offset¡ on weld properties¡ optimization using Response Surface method is performed and highest tensile strength is achieved. By increasing the rotational speed and tool offset to aluminum side and reducing the linear speed¡ the generated heat input during welding was increased and this caused to increasing UTS to a maximum and then decreased. By varying the process parameters and increasing the heat input until optimize strength¡ mixing operations are performed as appropriate and increases the tensile strength¡ with a further increasing in heat input¡ grains are being coarse and intermetallic compounds increases and then tensile strength has been decreased.