Analysis of first mode of metal transfer in friction stir welded plates by image processing technique

The metal flow phenomenon in friction stir welding (FSW) comprised of two modes of metal transfer. The first mode of metal transfer taking place layer by layer and is caused by the shearing action of the tool shoulder, while the second mode is caused by the extrusion of the plasticized metal around the pin. The aim of the present study is to quantitatively determine the amount of metal transferred by the first mode and its effect on strength of the weld. The images of the fractured faces of the samples are captured and processed to identify and distinguish the two modes of metal transfer. Quantitative analysis of the fractured surface and reveals existence of a possible linear correlation between the first mode in the fractured surface and the ultimate tensile strength, which controls the presence of defect in the weld.