FINITE ELEMENT SIMULATIONS OF HEAT TRANSFER IN FRICTION STIR WELDING OF AL 6061

Friction stir welding (FSW) is a process in the solid state in which heat is generated due to friction between welding tool and work piece. FSW has extensive effect on the microstructure, weld quality, and mechanical properties. The purpose of this investigation is to study and to predict the heat generated in Aluminum alloy plates welded by FSW method. A three dimensional model was developed by LS-Dyna software, using finite element method. An appropriate heating cycle has been proposed for aluminum 6061 alloy. The investigated parameters in this study were linear velocity and rotational velocity. Finally, results from numerical and experimental data was compared and verified

Microstructural evolution in friction stir welded API 5L-X52 steel

Abstract: Welded API-5L steel pipes have been extensively used in the oil industry. One of the major parameters affecting the mechanical properties is the grain size, which is altered with the joining method. In this paper microstructural evolution in the friction stir welded API 5L-X52 steel pipes has been investigated.Specimens were cut from a 2mm thick API 5L-X52 steel pipe. The steel sheets were then joined by friction stir welding process; at a linear speed of 100 mm/min. The tool rotational speed was varied from 400 to 800 rpm. Samples were then evaluated using tensile test, metallographic and hardness measurements. Microstructural investigations revealed the stir zone, heat affected zone and thermo mechanically affected zones. Heat input in the stir zone led to the formation of elongated austenite grains which were transformed to fine ferrite and pearlite grains and widmanstatten ferrite in certain regions. Plastic deformation and recrystallization enhanced the hardness and tensile strength as well as toughness of the welded joint in the API 5L-X52 steel