مشخصات پژوهش

In this paper, it has been presented that with macroscopic study of nugget and using effective distance (ED) index, the reason of different strength of joints, which are welded with different parameters and from different materials, can be explained. Welds that have longer ED carry more static lodes compared to others. ED is the linear distance of Hook tip, i.e., the separation point of two overlapped sheets in partially bounded region which is crack initiation point, and keyhole It has presented that Hook tip geometry also is an important factor that affects joint strength. The zig-zag Hook tip type is present at high strength welds while straight Hook tip can be seen for low strength joints Lower tool rotational speed and higher tool plunge rate result longer ED and higher shear strength. ED is shorter for joints that are welded from dissimilar alloys compared to similar ones and joint strength differs similarly The highest shear strength was 3050 N which was obtained with specimen that was welded from similar 6063T3 aluminum sheets with tool rotational speed of 800rpm and tool plunge rate of 80mm/min. For this specimen, effective distance was 2025 μm.