Study on the effect of electromagnetic field on the segregation and structural property of Ni60 cladding layer

The Ni60 alloy cladding layer is prepared using electromagnetic field assisted laser cladding to investigate the effect of the variation of current magnitude and direction on its segregation and structure. The macrosegregation and the structural property of the Ni60 cladding layer are analyzed by Optical Microscopy (OM), Back Scattered Electron Imaging (BSE), Energy Disperse Spectroscopy (EDS), X-ray Diffractometry (XRD), microhardness tester, and electrochemical corrosion. The results indicate that the macrosegregation and microsegregation decrease first and then increase with rising direct current (DC) or alternating current (AC) under constant magnetic field intensity.and microhardness tends to increase and then decrease with rising current magnitude. The increasing current has a prominent effect on the bottom of the cladding layer in terms of dendrite fragmentation and structural refinement. The reduction of segregated phases such as CrB and Cr7C3 enhances the solid solution strengthening of Cr and increases the microhardness of the cladding layer. The cladding layer applied with 200 amps AC is characterized by the lowest microsegregation rate and the highest microhardness of 772 HV0.2. The specimen has a high self-corrosion potential, the lowest self-corrosion current density, and the lowest passivation current density.