A computational study on the three-dimensional printability of precipitate-strengthened nickel-based superalloys

Abstract

This paper presents a computational framework to study the differences in process-induced microvoid and precipitate distributions during selective laser melting (SLM) of two nickel-based superalloys representative of low (IN718) and high (CM247LC) volume fraction precipitate-strengthened alloys. Simulations indicate that CM247LC has a higher propensity to form process-induced microvoids than IN718. Particle sintering is predicted to be strongly influenced by the powder size distribution. For deposition thickness of approximately 40 μm, thermal gradients during cooling are predicted to be larger for CM247LC than IN718 and consequently expect the development of larger residual stresses for a high volume fraction γ ′ alloy. A coupled mean field/finite-element approach has been used to predict the precipitate distributions across a simple rectangular build and during a subsequent hot isostatic pressing (HIP) cycle. Unimodal and multi-modal particle distributions are predicted for IN718 and CM247LC at the end of the SLM, respectively. A higher volume fraction of γ ′ is predicted for CM247LC at the end of the SLM process. During HIP, simulations indicate a dramatic increase in the γ ′ volume fraction in CM247LC, which can result in a reduction in stress relaxation and lead to a ductility drop.

Digital materials design by thermal-fluid science for multi-metal additive manufacturing

“…Given the improved computational power, numerical simulation based on thermal-solutal-fluid flow formulation has been becoming a powerful tool to elucidate detailed multi-scale physics of metal AM [7,[16][17][18][19][20][21][22][23][24][25][26][27][28]. For example, melt pool/keyhole formation [16][17][18][19][20][21][22][23][24]28] and spattering and denudation [19,20,26] were reproduced in simulation.…”

Conductivity Modulation of 3D‐Printed Shellular Electrodes through Embedding Nanocrystalline Intermetallics into Amorphous Matrix for Ultrahigh‐Current Oxygen Evolution

“…[14,15,21] The bright-field and dark-field TEM images in Figure S1, Supporting Information, also identify that the nanosized Ni 3 Nb phase was dispersedly distributed in the matrix phase of Ni-Fe-Cr, which can be credited to the melting and re-melting of fine powder in the micron length and time scales by the SLM technique. [15,22] Figure 3f illustrates the HRTEM image of the middle region of the activated layer, together with corresponding inset SAED patterns. The HRTEM revealed the presence of nanocrystallites of about 2-5 nm diameter (indicated by dashed lines in Figure 3e,f).…”

Dimensional Deviation Management for Selective Laser Melted Ti6Al4V Alloy Blade

“…During the SLM process, the metal powder is rapidly melted by the laser beam to form a molten pool (Manvatkar et al, 2015), and then, it cools and solidifies rapidly due to the extremely fast laser scanning speed, resulting in a steep temperature gradient near the molten pool (Vasinonta et al, 2006). The great temperature gradient makes the trend of expansion and contraction among the various parts inside the component, which generate thermal stress and thermal deformation during the forming process, and form residual stress and residual deformation after the end of construction (Mercelis and Kruth, 2006;Kruth et al, 2012;Cheng et al, 2016). These problems directly affect the dimensional accuracy and functional performance of the components (Rossini et al, 2012).…”