Revisiting fundamental welding concepts to improve additive manufacturing: From theory to practice

By J. P. Oliveira, Telmo G. Santos, R. Miranda. 2020

553 citations recorded by the source corpus.

Abstract Additive manufacturing technologies based on melting and solidification have considerable similarities with fusion-based welding technologies, either by electric arc or high-power beams. However, several concepts are being introduced in additive manufacturing which have been extensively used in multipass arc welding with filler material. Therefore, clarification of fundamental definitions is important to establish a common background between welding and additive manufacturing research communities. This paper aims to review these concepts, highlighting the distinctive characteristics of fusion welding that can be embraced by additive manufacturing, namely the nature of rapid thermal cycles associated to small size and localized heat sources, the non-equilibrium nature of rapid solidification and its effects on: internal defects formation, phase transformations, residual stresses and distortions. Concerning process optimization, distinct criteria are proposed based on geometric, energetic and thermal considerations, allowing to determine an upper bound limit for the optimum hatch distance during additive manufacturing. Finally, a unified equation to compute the energy density is proposed. This equation enables to compare works performed with distinct equipment and experimental conditions, covering the major process parameters: power, travel speed, heat source dimension, hatch distance, deposited layer thickness and material grain size.

Subfields: Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/39d29a26e824ae7c49632bdc8e1f309088f52404

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In Mechanical Engineering

1. Telmo G. Santos
2. J. P. Oliveira
3. Volker Wesling
4. Kai Treutler
5. Z. Qi
6. D. Jafari
7. Ian Gibson
8. T. Vaneker

Citations in the corpus

• The Current State of Research of Wire Arc Additive Manufacturing (WAAM): A Review (2021, background): “and process behavior is widespread, and the known fundamentals can be transferred [6,7].”
• Hot forging wire and arc additive manufacturing (HF-WAAM) (2020, background): “WAAM is based on multiple-pass welding and its metallurgy [2]; thus, the microstructure of the parts consists of coarse columnar grain structures [3] as a consequence of the successive re-melting and solidification thermal cycles.”
• Recent advances in hot tearing during casting of aluminium alloys (2020, background): “Because the AM exhibits certain similar characteristics to those of welding [124], in the future, this granular approach can be extended to the AM process to predict the Fig.”
• Wire and arc additive manufacturing: Opportunities and challenges to control the quality and accuracy of manufactured parts (2021, background): “Despite its extensive use, it is worth noting that these equations have some restricting hypotheses, such as heat dissipation simply by conduction under conditions of equilibrium, it considers punctual heat sources, neglecting surface radiation and convection losses in the dynamic molten pool [95].”
• High-throughput synthesis of Mo-Nb-Ta-W high-entropy alloys via additive manufacturing (2020, background): “While broad size ranges of powders and the presence of irregularly shaped powders have been linked to defects, including lack-of-fusion porosity, in additively manufactured parts using powder-bed techniques [26,27], it is still unclear that this relationship applies to parts manufactured through DED”
• The effect of laser scanning strategies on texture, mechanical properties, and site-specific grain orientation in selective laser melted 316L SS (2020, result): “The solidi fi cation microstructural features obtained during SLM is well studied in literature and is similar to the microstructural aspects observed during the welding process [27].”
• In-situ strengthening of a high strength low alloy steel during Wire and Arc Additive Manufacturing (WAAM) (2020, background): “…key characteristics, such as: large similarity with arc welding processes, where an extensive knowledge of the process parameters on different materials effects already exist; high deposition rates and material usage efficiency; and, finally, its ability to produce near-net-shape parts [2 – 4].”
• Wire and arc additive manufacturing of a Ni-rich NiTi shape memory alloy: Microstructure and mechanical properties (2020, background): “collumnar at the bottom and equiaxed at the top 410 along the height of the WAAM part can explain the irrecoverable strain of the as-built 411 part [64].”