Effect of tool offset and tilt angle on weld strength of butt joint friction stir welded specimens of AA2024 aluminum alloy welded to commercial pure cupper

Abstract

The aim of the present work is to investigate the mechanical properties and microstructure of butt joints friction stir welded (FSW) of dissimilar material specimens welded with single pass .The material used is AA2024 aluminum alloy  5 mm thick and pure commercial copper   .20 mm Flat shoulder tool  6 mm Pin diameter with a rotational speed of 900 rpm and 25 mm/min feed  is used in this work ,the tool is tilted 2^o to the Z axes of the machine. The welded specimens have been tensile tested at room temperature in order to analyze the mechanical properties with respect to the parent metals. The microstructure of the welded specimens has been studied by employing optical microscopy. Micro-hardness examination is also performed on the welded specimens. FSW specimens welded with flat shoulder tool  and 2^o tilt angle showed higher ultimate stress  than the specimens welded with flat shoulder tool and zero tilt angle . Specimens welded with 1 mm pin offset showed higher strength than the specimens welded with 0.5 and 1.5 mm pin offset.

Keywords: Friction stir welding, subsequent passes , mechanical properties