Laser beam treatment effect on AMPCO M4 bronze cavitation erosion resistance

Abstract

Ship propellers must resist simultaneously to ocean water corrosion and cavitation erosion. Until now, the best material used is the bronze with great copper content. These materials are expensive and there is the tendency to reduce the copper content while maintaining good properties. Such a material is AMPCO M4 used for manufacturing details for aircraft retractable landing assemblies. As a consequence we undertake cavitation erosion tests upon this bronze. In natural state (cast or even extruded) the cavitation resistance is not acceptable so, we improved the specimens by treating them with laser beams at three different impulse powers (160, 180 and 220 W). The cavitation erosion resistance was tested in the Cavitation Laboratory of Timisoara “Politehnica” University using a vibratory device respecting the conditions imposed by ASTM G32-2010 Standard. The comparisons with the genuine material (without any treatments) show that the applied procedure increased the hardness of the melted layer as well as the cavitation erosion behavior.