Experimental investigation on the slurry erosion and corrosion characteristics of friction stir welded AA5052 in the marine environment

Abstract

Materials with superior strength-to-weight ratio and corrosion resistance, such as aluminum alloy (AA5052), are favored in marine applications. Friction stir welding of these alloys can help create flawless joints. These alloys during maritime applications, are subjected to erosion and corrosion caused by the salt and sand in the water, and the non-welded and welded regions undergo variable levels of erosion and corrosion. Therefore, the erosion that the AA5052 experiences in the maritime environment is examined in both cast and friction stir welded (FSW) conditions in the present work. The potentiodynamic-polarization along with immersion-technique is used to evaluate the corrosion resistance of both cast and FSW aluminum alloy samples. The results revealed that the FSW sample possessed a 12 times higher corrosion rate than the cast, which is contributed by the refined grains and intermetallic phases like Al₃Fe in it. The erosion test is executed using a pot-type slurry erosion tester using sand and 3.5 % saline water as a slurry at slurry concentrations of 100, 300, and 500 g/L and slurry speeds of 500, 1000, and 1500 rpm while maintaining slurry particle size, slurry temperature, and slurry pH constant. The FSW sample displayed only a marginal erosion resistance when compared to the cast whereas the erosion rate in both enhanced at higher slurry speeds and slurry concentrations. In both the cast and FSW samples, the material removal is triggered by the plastic deformation caused by the impinging sand particle's kinetic energy. An increase in slurry concentration from 100 to 500 g/L and slurry speed from 500 to 1500 rpm enhanced material removal to about 95 % and 400 % respectively.