A detailed study of pre-heating effects in electron beam melting powder bed fusion process

Journal Article · Fri Jan 17 23:00:00 EST 2025 · Additive Manufacturing

DOI:https://doi.org/10.1016/j.addma.2025.104656· OSTI ID:2563340

Landau, E. ^[1]; Ganor, Y. I. ^[2]; Braun, D. ^[3]; Strantza, M. ^[4]; Matthews, M. J. ^[4]; Tiferet, E. ^[3]; Ziskind, G. ^[5]

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1. Ben-Gurion University of the Negev, Beer-Sheva (Israel); Nuclear Research Center Negev (NRCN), Beer-Sheva (Israel)
2. Ben-Gurion University of the Negev, Beer-Sheva (Israel); Rotem Industries LTD, Mishor Yamin, Arava (Israel); Nuclear Research Center Negev (NRCN), Beer-Sheva (Israel)
3. Rotem Industries LTD, Mishor Yamin, Arava (Israel); Nuclear Research Center Negev (NRCN), Beer-Sheva (Israel)
4. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
5. Ben-Gurion University of the Negev, Beer-Sheva (Israel)

Metal-based additive manufacturing processes, such as powder bed fusion with electron beam (PBF-EB) process, also referred to as electron beam melting (EBM), can produce high-density parts with minimal residual stresses due to the uniform and coherent preheating of the powder bed. However, understanding and controlling the multiple stages of preheating is required to enable the production of high-quality, consistent parts of various materials. This work presents a large-scale, multi-layer, three-dimensional numerical analysis focused on studying the preheating stages for predicting thermal history during the PBF-EB process. The model follows a continuous multi-stage cyclic process, that incorporates all the main stages of the PBF-EB process for 316 L stainless steel. This includes the gradual deposition of a new powder layer, the first and second preheating levels of the powder bed, and the energy deposition during melting (excluding the actual melt-pool behavior simulation). The model employs an adaptive time-scaling approach that automatically adjusts the energy deposition for each solution time-increment. This allows for localized changes in time-resolution over an otherwise computationally expensive multi-layer procedure. The material property variations are also taken into account, with an emphasis on the subtle irreversible changes in powder effective thermal conductivity after the two requisite preheating stages of the powder bed. This effect is studied using simplified conductivity models from the literature for partially sintered powder, validated by a dedicated experiment and numerical simulation. The large-scale model is then used to estimate the actual temperatures during first and second preheating levels for 316 L steel, which is not yet fully supported commercially for PBF-EB. Model predictions are corroborated by experiments, using and analyzing IR images, taken at the completion of each layer by the machine’s built-in infrared camera. The current model also incorporates a qualitative assessment for the effects of conductivity change during pre-heating, as well as evaluates the applicability of the time-scaling approach.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); Pazy Foundation
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 2563340
• Report Number(s): LLNL--JRNL-870435; 1103905
• Journal Information: Additive Manufacturing, Journal Name: Additive Manufacturing Vol. 99; ISSN 2214-8604
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
EBM
Multi-scale model
Numerical simulation
Powder conductivity
Pre-heating