The scope of this paper is to understand the effect of multiple pass of the tool during friction stir welding process of Al-17Si alloy and evaluate its microstructure and tensile strength. The rotational speed of 900 rpm with three different feed rates (50, 100, 150 mm/min) was selected for this process. The weld gap seen below the tool tip has been reduced drastically during the multiple pass and after the third pass the weld gap was invisible. With the increase in the feed rate, the adhesion was reduced between the tool pin circumference and diffused material, hence a small increase in the weld gap was observed. The substantiate changes in the microstructure was observed due to the severe formation of the metal during low feed rate. With the increase in the feed rate, some coarse grains were observed near and below the tool pin. The tensile strength during the multiple pass of the tool was studied and found better for lower feed rate. Further, the variation of the tool speeds (600, 900 and 1200 rpm) for constant feed rates of 100 mm/min were discussed. The more heat input improves plunging depth thereby reduces weld gap, but for higher heat input (tool rotation: 1200 rpm; feed rate: 100mm/min) increase in weld gaps was seen. The tensile properties for all the cases were discussed. The diffusion process, friction force and relative velocity pertaining to this process were highlighted finally.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.