Oxide films in laser additive manufactured Inconel 718

  1. Get@NRC: Oxide films in laser additive manufactured Inconel 718 (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1016/j.actamat.2013.07.039
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Journal titleActa Materialia
Pages65626576; # of pages: 15
SubjectAdditive Manufacturing; Continuous waves; Failure mechanism; Fracture surfaces; Laser depositions; Parent materials; Tensile fracture surfaces; Thermo dynamic analysis; Alloying elements; Deposition; Fiber lasers; Hydrogen embrittlement; Inert gases; Intermetallics; Manufacture; Niobium; Niobium compounds; Scanning electron microscopy; Sodium compounds; Soldering alloys; Tensile strength; Tensile testing; Thermoanalysis; Welding; Wetting; Oxide films
AbstractA continuous-wave 5 kW fiber laser welding system was used in conduction mode to deposit Inconel® alloy 718 (IN718) by employing filler wire on as-serviced IN718 parent material (PM) substrates. The direct laser deposited (DLD) coupons and as-serviced IN718 PM were then evaluated through tensile testing. To understand the failure mechanisms, the tensile fracture surfaces of the as-serviced IN718 PM, DLD and DLD-PM samples were analyzed using scanning electron microscopy. The fracture surfaces revealed the presence of both Al 2O3 and Cr2O3 films, although the latter was reasoned to be the main oxide in IN718. Both the experimental observations and thermodynamic analysis indicated that oxidation of some alloying elements in IN718 cannot be completely avoided during manufacturing, whether in the liquid state under vacuum (for casting, the electron beam melting, welding and/or deposition) or with inert gas protection (for welding or laser deposition). The exposed surface of the oxide film on the fracture surface has poor wetting with the metal and thus can constitute a lack of bonding or a crack with either the metal and/or another non-wetted side of the oxide film. On the other hand, the wetted face of the oxide film has good atom-to-atom contact with the metal and may nucleate some intermetallic compounds, such as Laves, Ni3Nb-δ, Nb-rich MC and γ′ compounds. The potential of their nucleation on Cr 2O3 was assessed using planar disregistry. Coherent planes were found between these intermetallics and Cr2O3.
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AffiliationNational Research Council Canada (NRC-CNRC); Aerospace
Peer reviewedYes
NPARC number21269905
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Record identifier5a03ad02-3906-406a-864f-c83f6beecfa8
Record created2013-12-13
Record modified2016-05-09
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