THE EFFECT OF FRICTION STIR WELDING ON THE MICROSTRUCTURE AND TENSILE PROPERTIES OF AL 2139-T8 ALLOYS

The welding process introduces heat, plastic deformation, and chemical variation into the weld joints and alters the microstructure, strength, and ductility of the welded region. In this research, two plates of Al 2139-T8 alloys were welded together by friction stir welding (FSW). An evaluation of the crystallographic texture, grain size, and morphology of the grains in the FSW region, in comparison to those of the grains outside of the weld region, was made by scanning electron microscopy (SEM) and electron backscattered diffraction. In addition, the quasi-static tensile behavior of samples from the FSW region and those from outside of the FSW region was characterized by in-situ tensile experiments in the SEM with digital image correlation. It was found that the ultimate tensile strength was greater in the samples from outside FSW region and the elongation was greater for samples from the FSW region. The full results of the effect of the FSW on the Al 2139 microstructure and tensile behavior will be discussed in detail.