Cavitation resistance of Stellite 21 coatings tungsten inert gas (TIG) deposited onto duplex stainless steel X2CrNiMoN22-5-3

Abstract

Cobalt-based alloys, called Stellite, have a microstructure consisting of complex carbides dispersed in a Co-based solid solution matrix. These alloys are resistant to corrosion, erosion through cavitation, abrasive, and sliding wear. To increase the erosion resistance through cavitation, hardfacing of the stainless steel duplex X2CrNiMoN22-5-3 with Stellite 21 alloy was performed using the pulsed tungsten inert gas (TIG) process. The positive effects of the hardfacing process are the low heat input, reduced distortions, controlled volume of the weld, and reduced susceptibility to hot cracking. The effect of dilution is essential for the quality of the deposited layers and, in this sense, the TIG pulsed current welding process was performed to reduce the excess linear energy and implicitly the substrate melting. Iron dilution levels were in the range between 5.9 and 6.1. The higher Fe content in the first layer does not significantly reduce its hardness or wear resistance through erosion cavitation. Compared with the substrate material, the cavity erosion resistance increases 7 to 11 times even in the first layer hardened by the TIG pulsed current welding process.