Some studies on mechanical properties of friction stir butt welded Al-6082-T6 plates
The conventional fusion welding of cast aluminium alloys is generally difficult due to some common defects such as porosity, oxide inclusion, and hot cracking, which in turn reduce the weld strength. In recent years, friction stir welding (FSW) was found to be very effective for the welding of various wrought aluminum alloys. This paper investigates a metal joining process called Friction Stir Welding (FSW), an innovative welding technique invented by TWI Ltd. in Great Britain in 1991. The purpose of the paper is to study the effects of process parameters in the butt welding of Al-6082-T6 plates with a thickness of 3 mm. Joints were made using different combinations of tool rotation speed, welding speed, and axial force, each at different levels. The quality of weld zone was analyzed using macrostructure. The study aims in identifying the process parameters of welding the Al6082 alloy and the effect of welding speed on the weld performance of the joint was investigated by conducting tensile and hardness tests.
Design features for bobbin friction stir welding tools: Development of a conceptual model linking the underlying physics to the production process
The effects of different pin features and dimensions of scrolled shoulder bobbin friction stir welding were tested for welding marine grade aluminium, Al6082-T6. Welds were created in longitudinal and transverse plate extrusion directions in thin plate aluminium clamped and supported at one side. Measured outcomes included visual inspection, plate distortion, mechanical properties, metallurgical examination, and hardness test. This study shows that tool features cannot be directly transferable from conventional friction stir welding technology without comprising process variables and tool part functionality. Process setting such as clamps, support arrangements, shoulder gap and welding direction create compression, vibration and heat distribution hence influence the weld quality. The best joint was produced by four flats tool pin followed by threaded tool pin with three flats. These findings were used to develop a conceptual theory representing the underlying physics of the friction stir welding process. The effects of pin features, specifically threads and flats, are identified. This model is useful for direct linking welding factors towards the expected consequences.
Study of Spot Welding of Austenitic Stainless Steel Type 304
In this study, austenitic stainless steel type 304 were welded by resistance spot welding. The relationship of nugget diameter and welding current was investigated. Hardness distribution along welding zone was also investigated. The results indicated that increasing welding current gave large nugget diameter. The welding current did not much affected the hardness distribution.