Prospecting for the Surface Treatment of a Nickel-Aluminium Bronze Alloy Using the TIG Process

Abstract

In this study the TIG process was used to perform the surface treatment of Nickel-Aluminium Bronze alloy (C63280), the main material used in the industry for the manufacture of naval propellers. The process was applied in specimens obtained from a propeller blade at different current pulsation frequencies (2, 5, 6, 12 Hz and 30 kHz) and without pulsation. The treatments were submitted to microstructural and microhardness analysis, and the results were compared to the material without any treatment. As for the microstructural aspect, all treatments resulted in grain refining, as this aspect is more accentuated for the frequency of 6Hz. The analysis also revealed a lower volume of the α phase in all treatments, which was evidenced upon investigation of the microhardness, with dispersion of the β phase in all samples and the k phase in some samples. The results show a greater uniformity in the microhardness in the treated zone due to grain refining. However, when comparing the average microhardness with the microhardness of the reference material, a significant increase of the microhardness was reached only at the frequency of 6Hz.

Keywords:
Nickel-Aluminium bronze alloy; Naval propellers; Surface treatment; TIG; Current pulsation