Enhancement of cavitation erosion and corrosion resistance of brass by laser surface alloying with Ni-Cr-Si-B

Brass (Cu-38% Zn-1.5% Pb) was surface-alloyed with a hardfacing Ni-Cr-Si-B powder (Ni-16.5% Cr-3.5% Si-3.8% B-15.5% Fe-< 1% C) using a high-power continuous-wave Nd-YAG laser with different processing parameters for improving the cavitation erosion and corrosion resistance in 3.5 wt.% NaCl solution. The cavitation erosion resistance R-e (defined as the reciprocal of the mean erosion rate) of the alloyed layer ranged from 6. 10- to 9.06-fold that of the brass substrate, and was found to be closely related to the hardness of the alloyed layer. The corrosion resistance was also improved, as indicated by a noble shift in the pitting potential and a reduction in the corrosion current density. The difference in the cavitation erosion and corrosion behavior of various specimens is discussed in relation to their microstructures and structures via studies using optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX) and X-ray diffractometry (XRD). The present study also indicated that it is difficult to achieve maximum improvement in cavitation erosion and corrosion resistance simultaneously. (C) 2002 Elsevier Science B.V. All rights reserved.