Effect of processing current on microstructural evolution and orientation information in Ni-based single crystal superalloy during plasma re-melting

The microstructural evolution and orientation information in the plasma re-melted Ni-based single crystal superalloy are systematically researched. The bowl-shaped FZ with small depth/width ratio is obtained under a wide range of processing current. The re-precipitated γ' phase in the position of origin γ' phase is apparently larger than that in the position of origin γ matrix at the bottom part of HAZ, and more γ' phase re-precipitates in the origin γ matrix under larger processing currents in the HAZ. The γ' phase in the interdendrite is larger than that in the dendrite core and both increase with the processing current rising. No obvious element burning occurs during the re-melting and the segregated degree for each element hardly changes from 25 to 45 A. The transition regions exist higher plastic strain than inside the dendrite zones except at 45 A. The low plastic strains at 25 and 45 A are respectively attributed to the few transition regions and extensive stray grains formation. The 25 and 30 A are more suitable considering the position and area fraction of stray grains together with the orientation deviation in general. The results display the potential possibility for the repairing by plasma besides the current technologies.