Computational modeling of residual stress formation during the electron beam melting process for Inconel 718

Abstract

A computational modeling approach to simulate residual stress formation during the Electron Beam Melting (EBM) process within the Additive Manufacturing (AM) technologies for Inconel 718 is presented in this paper. The EBM process has demonstrated a high potential to fabricate components with complex geometries, but the resulting components are influenced by the thermal cycles observed during the manufacturing process. When processing nickel based superalloys, very high temperatures (approx. 1000 • C) are observed in the powder bed, base plate, and build. These high temperatures, when combined with substrate adherence, can result in warping of the base plate and affect the final component by causing defects. It is important to have an understanding of the thermo-mechanical response of the entire system, that is, its mechanical behavior towards thermal loading occurring during the EBM process prior to manufacturing a component. Therefore, computational models to predict the response of the system during the EBM process will aid in eliminating the undesired process conditions, a-priori, in order to fabricate the optimum component. Such a comprehensive computational modeling approach is demonstrated to analyze warping of the base plate, stress and plastic strain accumulation within the material, and thermal cycles in the system during different stages of the EBM process.

Invited review article: Metal-additive manufacturing—Modeling strategies for application-optimized designs

“…One of the main strategies mentioned in the literature is preheating the baseplate and/or powder bed before depositing or melting the first layer of material. Vastola et al (2016) calculated that a 50°C increase in the powder bed temperature in EBM showed a decrease of 20% in residual stresses, and this suggestion was similarly proposed by Prabhakar et al (2015) [83,84]. This strategy greatly reduces the thermal gradients and subsequent thermal stresses that are incumbent during processing.…”

Sliding Contact Wear Damage of EBM built Ti6Al4V: Influence of Process Induced Anisotropic Microstructure

“…It is because the presence of thin fluid film reduces the friction coefficient as in Figure 10c,d and assist rapid oxide film reformation. In addition, the rapid solidifications during EBM process may develop residual stress field [31]. Elastic residual strains increase thermodynamic potential and ultimately accelerates electrochemical reaction of the mechanically disturbed surfaces [32,33].…”

A scalable parallel finite element framework for growing geometries. Application to metal additive manufacturing

“…[7][8][9][10][11] At the part scale, finite element (FE) modelling has proved to be useful to assess the influence of process parameters, 12 compute temperature distributions, 13,14 or evaluate distortions and residual stresses. [15][16][17] Recent contributions have introduced microstructure simulations of grain growth 18,19 and crystal plasticity, 20 melt-pool-scale models 3,21 and even multiscale and multiphysics solvers. [22][23][24][25][26] Furthermore, advanced frameworks (eg, grounded on multilevel hp-FE methods combined with implicit boundary methods 27 ) or applications to topology optimisation 28 have also been considered.…”