Subsurface Defect Evaluation of Selective-Laser-Melted Inconel 738LC Alloy Using Eddy Current Testing for Additive/Subtractive Hybrid Manufacturing

New materials and manufacturing technologies require applicable non-destructive techniques for quality assurance so as to achieve better performance. This study comprehensively investigated the effect of influencing factors including excitation frequency, lift-off distance, defect depth and size, residual heat, and surface roughness on the defect EC signals of an Inconel 738LC alloy produced by selective laser melting (SLM). The experimental investigations recorded the impedance amplitude and phase angle of EC signals for each defect to explore the feasibility of detecting subsurface defects by merely analyzing these two key indicators. Overall, this study revealed preliminary qualitative and roughly quantitative relationships between influencing factors and corresponding EC signals, which provided a practical reference on how to quantitively inspect subsurface defects using eddy current testing (ECT) on SLMed parts, and also made solid progress toward on-line ECT in additive/subtractive hybrid manufacturing (ASHM) for fabricating SLMed parts with enhanced quality and better performance.

Effect of Cutting Fluid on Milling of Additively Manufactured Inconel 738LC

This study focuses on the effect of cutting fluid on sample surface integrity and tool wear in milling additively manufactured Inconel 738LC. Sample surface integrity and tool wear characterization was undertaken using scanning electron microscopy, backscatter electron microscopy, energy dispersive spectroscopy, laser scanning confocal microscopy, ultra-depth of field digital microscope system and digital display hardness tester. Compared with dry milling, wet milling not only provides an entirely different result on surface morphology, but also shows less surface plastic deformation, and smaller surface roughness. In addition, the tool wear mechanisms of wet milling are found to be different compared to dry milling.

The Defect Analysis of Inconel 738LC with Computed Tomography Inspection

In the present paper, computed tomography (CT) inspection is shown. The CT inspection method allowed to rate the density of defects hidden inside a material, which has a significant role in the live material. The method allows to evaluate the reliability of tensile test’s results. In our analysis, the position of crack propagation was determined by CT, and the tensile test was performed to check the accuracy of the nondestructive method. The tensile tests were performed on Inconel 738LC [1] samples.