Investigation of microstructure and mechanical properties of friction stir welded particle reinforced and unreinforced metal powder 7039 Al alloy

In this study 10wt. % SiC reinforced and unreinforced 7039 Al alloy plates were produced by powder metallurgy method. Powders which are forming the mixture were cold pressed at pressing pressure of 300 MPa, after the homogenous mixture obtained in a mixer (Turbula mixer). After pressing process, block samples in same diameter and height (100x100 mm) were produced. These block samples were exturuded in the ratio of ¼ at temperature of 500 °C and plates with 24 mm thickness and 86 mm wideness were obtained. Subsequently plates thickness reduced to 4-5 mm by progressive rolling process at temperature of 500 °C. After the rolling, aging was conducted by applying T6 heat treatment to the plate. Reverse guide tip in a diameter of 3 mm was used as mixer tip in friction stir welding process at rotation speed of 900 and 1400 rev / min and feed rate of 50 mm/min. Optical microscope and SEM examination were carried out to determine the microstructure; micro hardness, tensile and bending tests were performed to determine the mechanical properties of welded samples. It was found that there is no joining defect and it consists of four different microstructure (base metal, heat affected zone, thermomechanical affected zones, weld metal) by welding section investigations. It was found that hardness values of these regions were between 110-160 HV and mean ultimate tensile strength values were for unreinforced samples 352,15 MPa and reinforced samples 225,35 MPa .