Review on hardfacing of valve sealings in power plants with Inconel 625 alloy

Hardfacing of valve sealings in power plants with Inconel 625 alloy has been reviewed in this paper. The overlaying processes, overlay microstructures, and weldability issues during the hardfacing process have been analyzed. The results indicate that almost all melting welding processes can be used for hardfacing of Inconel 625 alloy. During hardfacing, it is necessary to strictly control the penetration, reduce the overlay dilution rate, so as to prevent the formation of partially mixed zone (PMZ) and solidification crack. From the perspective of controlling the penetration, reducing the overlay dilution rate, and automated hardfacing, the most suitable process for hardfacing Inconel 625 alloy on the valve sealings in power plants is cold metal transfer (CMT) welding process.