Microstructure and Tensile Property of Electromagnetic Stirring Assisted Laser Repaired Inconel718 Superalloy

Abstract

Inconel718 superalloy samples with V-grooves were experimentally repaired by electromagnetic stirring assisted laser repairing (EMS-LR) under different magnetic field currents. The effects of the magnetic field current on morphologies of single pass repaired zone (RZ), microstructure and mechanical properties of multilayer RZ were experimentally investigated. Microstructure observations show that metallurgical bonding is obtained between the RZ and the substrate when the optimized process parameter is used. The microstructure in RZ is coarse columnar crystal when no electromagnetic stirring is used, which grows epitaxially along the deposition direction. With the increase of magnetic field current, the convection of liquid metals prompts the transformation from coarse columnar to fine equiaxed grains. The strong scour of liquid metal convection can affect the interdendritic γ+Laves eutectic reaction and prohibit the growth of Laves phase. Electromagnetic stirring can improve the spreading of liquid metal in a certain extent. The width and deposition height of the single trace were measured and it is found that the width and deposition height ratio changes from 3.26 when no electromagnetic stirring is used to 3.33, 4.14 and 5.14 when the applied magnetic field current is 20, 40 and 60 A, respectively, and the penetration is found to be decreased inversely. The tensile strengths of repaired components increase from 487 MPa to 510, 673 and 770 MPa for magnetic field currents of 0, 20, 40 and 60 A, respectively.