Effect of Electron Beam Surface Modification on the Plasticity of Inconel Alloy 625

Abstract

In the present work, we present results on the influence of electron beam surface modification on the resistance to plastic deformation and plasticity of Inconel alloy 625. During the treatment procedure, the electron beam currents were 10 and 20 mA, corresponding to beam powers of 600 W and 1200 W. The structures of the modified specimens were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The nanohardness and Young’s modulus were studied through nanoindentation experiments. The plasticity of the treated materials as well as of the untreated ones was studied through an evaluation of H3/E2, which points to resistance to plastic deformation. The results obtained show that the electron beam surface modification procedure leads to a reorientation of microvolumes and the formation of a preferred crystallographic orientation. The surface treatment of the samples using an electron beam with a power of 600 W did not lead to major changes in the structures of the samples. However, the use of a beam with a power of 1200 W led to the formation of a clearly separated modified zone with a thickness in the range of 13 to 15 μm. The Young’s modulus increased from about 100 to 153 GPa in the case of electron beam surface modification using the lower-power electron beam. The application of the higher-power electron beam did not lead to a significant change in the modulus of elasticity as compared to the untreated specimen. Also, it was found that the treatment procedure pointed to a decrease in nanohardness when the maximum power of the electron beam was applied. The resistance to plastic deformation, i.e., the H3/E2 ratio, showed that the ratio decreased significantly in both cases of electron beam surface modification, pointing to an improvement in the plasticity of the surface of the Inconel alloy 625.