Microstructural and Tensile Properties Anisotropy of Selective Laser Melting Manufactured IN 625

Abstract

The present study was focused on the assessment of microstructural anisotropy of IN 625 manufactured by selective laser melting (SLM) and its influence on the material’s room temperature tensile properties. Microstructural anisotropy was assessed based on computational and experimental investigations. Tensile specimens were manufactured using four building orientations (along Z, X, Y-axis, and tilted at 45° in the XZ plane) and three different scanning strategies (90°, 67°, and 45°). The simulation of microstructure development in specimens built along the Z-axis, applying all three scanning strategies, showed that the as-built microstructure is strongly textured and is influenced by the scanning strategy. The 45° scanning strategy induced the highest microstructural texture from all scanning strategies used. The monotonic tensile test results highlighted that the material exhibits significant anisotropic properties, depending on both the specimen orientation and the scanning strategy. Regardless of the scanning strategy used, the lowest mechanical performances of IN 625, in terms of strength values, were recorded for specimens built in the vertical position, as compared with all the other orientations.

A Study on Using the Additive Manufacturing Process for the Development of a Closed Pump Impeller for Mechanically Pumped Fluid Loop Systems

“…For each building orientation, a set of two impellers was fabricated. Table 3 presents the process parameters used for the closed impeller fabrication as previously performed in the work done by Condruz et al [ 19 ]. Figure 4 comprises the four impeller CAD models with simulated printing support material and printing parameters, using RDesigner (version 2018, Realizer GmbH, Borchen, Germany) software.…”

Manufacturing of Closed Impeller for Mechanically Pump Fluid Loop Systems Using Selective Laser Melting Additive Manufacturing Technology

“…Additionally, the influence of process parameters on the specimen surface roughness and material hardness was assessed. The main conclusion was that for 250 W laser power, 700-800 mm/s scan speed, and layer thicknesses in the range of 30-50 µm, the relative densities achieved are over 99.5%, as highlighted by the authors in [30][31][32]. However, during the manufacturing of the closed impeller and due to the appearance of the adherent dross on the interior side of the impeller, subjected to analysis in [33], the laser power was decreased to 200 W, which was found to be the best corrective measure.…”

Tensile Notch Sensitivity of Additively Manufactured IN 625 Superalloy

“…However, it is not the purpose of this paper to analyze the anisotropy in grain structure and its relationship with the mechanical properties of the material. A deeper analysis of the microstructural and tensile properties and anisotropy of Selective Laser Melting in manufactured IN 625 is presented elsewhere [44].…”

“…Despite the fact that some of these defects can be avoided by optimizing the process parameters in order to obtain the highest possible densification, the existence of others is unavoidable due to the layer-by-layer manufacturing process and can lead to anisotropic mechanical properties. If the loading direction is parallel to the building direction, due to the inherent presence of the defects between successive layers, the load-bearing cross-section is reduced, and thus the tensile strength is lower than if the stress were applied transverse to the growth direction [44]. For specimens manufactured horizontally, as in the case of the present study, during tensile testing the load is applied along the built layers, orthogonal to the columnar grains' growth direction with influence on material ductility.…”