The Effect of Under Water Friction Stir Welding (UFSW) Variables on Microstructure and Mechanical Properties of 4343- Al alloy Weld

In this work the effects of welding parameters such as: Linear velocity (V)، Rotational speed (W)، and water temperature on microstructure and mechanical properties of (UFSW) 4343- Al alloy was investigated and it was compared with air (FSW) the tests out on both air and under water FSW with different welding pitch () and 4343 Al alloy butt joint. Visual inspection results show that surface quality of the welded samples in air and under water are similar، in addition optical microscope (OM) and scaning electron microscope (SEM) examination results show that by increasing of environment cooling intensity in constant، the grain size، precipitated phase and phases of weld nugget were decreased، the maximum decrease in grain size، and phase was gained in =0. 1 mm/r. The Hardness and tensile tests of welded nuggets show، that by increasing of environment cooling intensity in a constant، hardness، tensile strength and yield strength of weld nugget was increased and percentage of elongation was decreased، Moreover maximum hardness، tensile strength and yield strength of weld nugget was gained in =0. 1 that welded in under water at 2 water.