Investigation on microstructures and corrosion resistance of electron beam cladding NbMoCr on Inconel617

To improve surface properties of Inconel617 alloy (referred to as 617 alloy), NbMoCr cladding layer metallurgically bonded to substrate was prepared on the surface of 617 alloy by electron beam cladding. The microstructure, hardness and corrosion resistance of cladding layer were investigated. Furthermore, it was compared with those of 617 alloy. The results showed that the NbMoCr cladding layer had a more uniform structure, finer grains, fewer defects such as pores, and a small amount of hard phase such as M₂₃C₆, Cr₇C₃, Cr₄Si₄Al₁₃ and CoCx, which improves the surface hardness and corrosion resistance of the cladding layer, were formed. After the test, the hardness of the coating was 86HV10 higher than that of the 617 alloy. Electrochemical corrosion tests showed that the self-corrosion current density of 617 alloy was 5.16 times as that of NbMoCr cladding layer in 1 mol/L H₂SO₄ solution. In 3.5% NaCl solution, the self-corrosion current density of 617 alloy was 4.6 times as that NbMoCr cladding layer; In 1 mol/L NaOH solution, the self-corrosion current density of 617 alloy was 3.12 times as that of NbMoCr cladding layer.