Stellite-20 alloy claddings were prepared on the compacted graphite iron through plasma transfer arc cladding technology to strengthen the CGI substrate. The influence of plasma arc currents on the microstructure, hardness, and fracture toughness of the cobalt-based coating was investigated. Results showed that cobalt-based coatings were composed of equiaxed crystals and columnar dendrites with fcc structured cobalt-based solid solution and carbides, such as Cr₂₃C₆, M₇C₃. Further, the crystal grains became finer and a large number of hard phases precipitated along the grain boundaries with the increase of the cladding currents. The maximum microhardness of the claddings reached 530.78±65.59 HV_0.2 and the highest toughness of the cobalt based coating reached 165.34 MPa•m^½ when the plasma arc current was 60A.
 

Stellite-20 alloy,Coating,Microstructure,Microhardness,Fracture Toughness