Hot corrosion behavior of Inconel 625 alloys fabricated by selective laser melting
The hot corrosion behavior of Inconel 625 alloy fabricated by forged and selective laser melting(SLM)under 50%KCl+50%Na2SO4(mass fraction,%)salt film at 600℃was studied by electrochemical impedance spectroscopy.The results show that Nyquist plots of SLM Inconel 625 is composed of double capacitive loops,indicating that the corrosion is controlled by the charged transfer process through the scale.The Nyquist plots of forged Inconel 625 consist of a capacitive loop in high frequency zone with a line in low frequency zone,indicating that the corrosion is controlled by a diffusion process.The scale formed on SLM Inconel 625 shows a Cr2O3/Ni3S2 multilayer alternating structure,while the scale formed on the forged Inconel 625 alloys is composed of a mixture of Cr2O3 and NiO with the internal sulfidation occurred.A large amount of dislocations and sub-grains in the SLM Inconel 625 alloy promote the outward diffusion of chromium.The prompt oxidation of Cr alters sulfur partial pressure on the alloy,which affects the composition and structure of the scale formed on SLM alloy.
hot corrosionselective laser meltingInconel 625electrochemical impedance spectroscopydislocation density
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