Strengthening Effect of Nb on Microstructure and Cavitation Erosion Behavior of Duplex Stainless Steel Surfacing Layer

This paper reports the microstructure and corrosion behavior of a Nb-containing stainless steel surfacing layer prepared by tungsten inert gas (TIG) powder surfacing. The focus was to achieve a clear understanding of the relationships between the Nb-addition and cavitation erosion behavior. In order to eliminate the microstructure inhomogeneity of as-welded samples, solution heat treatment was carried out. It is considered to set the heat treatment temperature at 1150 °C and 1250 °C to minimize the precipitation phase. Results showed that due to the Nb addition the as-welded 22Cr9Ni3MoNb surfacing layer had higher hardness, a lower pitting potential, and better cavitation erosion resistance. Because of the existence of a great quantity of precipitates, heat treatment at 1250 °C had an adverse effect on the mechanical properties and cavitation erosion resistance of surfacing layer samples.