Effect of Grain Orientation on the Nitriding Rate of a Nickel-based Superalloy Inconel 690

Inconel 690, a nickel-based superalloy, was nitrided by means of plasma nitriding. SEM, XRD and Electron Backscatter Diffraction (EBSD) were employed to characterize the nitrided layer. The results indicate that a low temperature plasma nitriding of Inconel 690 produces a supersaturated nitrogen solid solution in austenite (γ N phase). The thickness of the γ N layer is different between grains with different grain orientation. The γ N layer grows faster in the grains with small θ 100han in the grains with large θ 100θ 100eing the smallest angle between the 100irection and growth direction of the nitrided layer. Furthermore, the thickness of the γ N layer shows an approximate linear relationship with θ 100