COMPARATIVE STUDY ON HARDNESS, TORSION AND MICROSTRUCTURAL CHARACTERISTICS OF FRICTION WELDED JOINTS OF Al 6061 ROD FORMED WITH VARIOUS INTERFACE GEOMETRY

Abstract

Friction welding is a solid state joining process that produces coalescence in materials, using the heat developed between surfaces through a combination of mechanical induced rubbing motion and applied load. In rotary friction welding technique heat is generated by the conversion of mechanical energy into thermal energy at the interface of the work pieces in contact during rotation under pressure. Recent studies revealed that one of the strong influencing factors which affect the tensile characteristics of the friction welded joints is the shape of interface geometry of the mating surfaces. The various interface geometry considered for those studies are Flat-Flat combination, Taper-Taper combination and Concex-Convex combination. It is reported that the Ultimate tensile tensile characteristics of friction welded joints with taper-taper and convex-convex combinations are higher than that obtained with flat-flat combination. Present study investigates the influence of these geometry on the other physical characteristics like hardness and mechanical properties like torsion. Attempts were made to analyze the variations in such properties from flat-flat combination based up on the microstructure studies carried out. The Taper angle considered for taper-taper combination is 30° and the radius of the convex-convex geometry considered is 20mm. The speed for the rotating specimen here is 775 rpm. The welding pressure was kept in the range 0.7-1.73 N/mm2. The forging pressure was kept in the range 1.73-2.76 N/mm2. The hardness and the Modulus of rigidity was found higher for the joints with taper-taper combination. Convex-Convex geometry also showed better modulus of rigidity than Flat-Flat combination, but less in the case of hardness value