Cavitation erosion damage of self-fluxing NiCrSiB hardfacings deposited by oxy-acetylene powder welding

Abstract

This paper comparatively investigates the cavitation erosion damage of two self-fluxing NiCrSiB hardfacings deposited via the oxy-acetylene powder welding method. Examinations were conducted according to the procedure given by ASTM G32 standard. In order to research cavitation erosion (CE), the vibratory apparatus was employed. The cavitation damaged surfaces were inspected using a scanning electron microscope, optical microscope and surface profilometer. The hardness of the A-NiCrSiB hardfacing equals 908HV while that of C-NiCrSiB amounts to 399HV. The research showed that the CE resistance of C-NiCrSiB is higher than that of A-NiCrSiB. The results demonstrate that in the case of multiphase materials, like the NiCrSiB hardfacings, hardness cannot be the key factor for cavitation erosion damage estimation whereas it is strongly subjected to material microstructure. In order to qualitatively recognise the cavitation erosion damage of the NiCrSiB self-fluxing hardfacings at a given exposure time, the following factors should be respected: physical and mechanical properties, material microstructure and also material loss and eroded surface morphology, both stated at specific testing time. The general idea for the cavitation erosion damage estimation of the NiCrSiB oxy-acetylene welds was presented.

Behaviour of nickel coatings made by brush plating technology in conditions of cavitation erosion and corrosion

“…9a). Very short as well as the lack of incubation period was also noted by Li et al [53], who tested 316L steel, Wantang et al [54], who tested martensitic HNS steel and two CrNiMo stainless steel grades, Liu et al [55], who tested Cr-Mn-N steels, Szala [56], who tested the NiCrSiB hardfacings, and Zakrzewska et al [42], who also tested nickel coating but deposited by the different method (the electroless method). With increasing testing time to 60 min, the volume loss increased to 0.22, 0.06 and 0.15 mm 3 , respectively for the uncoated steel, Nickel 1 and Nickel 2 coating.…”

“…Taking into account the properties of nickel coatings, the 43% higher hardness of the Nickel 1 coating compared to the Nickel 2 coating resulted in a 2.6 times lower final erosion rate despite the net of cracks. The effect of hardness on erosion resistance has been observed many times [56,59]. The presented test results showed that the erosion rate of the Nickel 2 coating was lower than that of the substrate despite the lower hardness of Nickel 2 compared to that of the substrate.…”