Effect of Temperature on Microstructure and Properties of Stellite6 and Stellite21 Alloys Surfacing Layer
Stellite6 and Stellite21 Co based alloys were surfaced on the 304H stainless steel by using plasma surfacing,respectively.The evolution of microstructure and properties of the Co based alloy surfacing layers under 550-650℃was studied.The microstructure of the surfacing layers and element distribution at the bonding zone were observed and analyzed by optical microscope,scanning electron microscope and electron microprobe.Microhardness and corrosion resistance of the hardfacing layers were measured by microhardness tester and electrochemical workstation,respectively.The results show that the microstructure of surfacing layer of the two alloys is composed of plane crystal,columnar crystal and equiaxed crystal.With the increase of temperature,the dendrite spacing of the surfacing alloys increases slightly,there is no obvious element diffusion at the fusion zone,and it has good microstructure stability.The microhardness of the surfacing layer of Stellite6 and Stellite21 alloys in welded state is 463,365HV0.3,respectively,and the hardness of surfacing layer of the two alloys decreases slightly after heating.The corrosion current density of surfacing layer of Stellite6 and Stellite21 alloys in welded state is 1.312,10.848 μA/cm2,respectively,and the corrosion current densities of the Stellite6 and Stellite21 alloys increase slightly after heating.Generally,the two alloys have high hardness and good corrosion resistance at 550-650℃.
Co based alloysurfacing layermicrostructurehardnesscorrosion resistance
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