Corrosion investigation of projection friction stir spot welding of Al 2024 sheets in oil and gas industry

In order to determine a suitable alternative welding method for substituation of fusion and resistance welding in oil and gas industry, a new method of projection friction stir spot welding with constant diameter and depth of protrusion is herein used for welding of 2024 aluminum sheets. By studying the previous research that was done on the friction stir spot welding of this material, the rotational speed of 800rpm is chosen for this purpose.For this purpose, the microstructure along with corrosion behavior of projection friction stir spot welding of Al2024 joints is investigated as a novel welding technique in oil and gas sector which produces reliable, safe, smooth and keyhole-free joints. The microstructural changes of different welding areas are studied by novel field emission scanning electron microscopy and consequently the hardness profiles of different areas is drawn. The effect of corrosive oil solution containing salts on welded specimens is studied and various types of pitting and intergranular corrosion are observed in different welding areas. Eventually, accumulation of corrosion products are observed in the stirred area of the weld and the TMAZ shows the highest rate of intergranular corrosion.