Short-term creep behavior of an additive manufactured non-weldable Nickel-base superalloy evaluated by slow strain rate testing
Artikel i vetenskaplig tidskrift, 2019

Additive manufacturing (AM) of high γ′ strengthened Nickel-base superalloys, such as IN738LC, is of high interest for applications in hot section components for gas turbines. The creep property acts as the critical indicator of component performance under load at elevated temperature. However, it has been widely suggested that the suitable service condition of AM processed IN738LC is not yet fully clear. In order to evaluate the short-term creep behavior, slow strain rate tensile (SSRT) tests were performed. IN738LC bars were built by laser powder-bed-fusion (L-PBF) and then subjected to hot isostatic pressing (HIP) followed by the standard two-step heat treatment. The samples were subjected to SSRT testing at 850 °C under strain rates of 1 × 10−5/s, 1 × 10−6/s, and 1 × 10−7/s. In this research, the underlying creep deformation mechanism of AM processed IN738LC is investigated using the serial sectioning technique, electron backscatter diffraction (EBSD), transmission electron microscopy (TEM). On the creep mechanism of AM polycrystalline IN738LC, grain boundary sliding is predominant. However, due to the interlock feature of grain boundaries in AM processed IN738LC, the grain structure retains its integrity after deformation. The dislocation motion acts as the major accommodation process of grain boundary sliding. Dislocations bypass the γ′ precipitates by Orowan looping and wavy slip. The rearrangement of screw dislocations is responsible for the formation of subgrains within the grain interior. This research elucidates the short-creep behavior of AM processed IN738LC. It also shed new light on the creep deformation mechanism of additive manufactured γ′ strengthened polycrystalline Nickel-base superalloys.


Laser processing

Nickel-base superalloy

Grain boundary sliding



Jinghao Xu

Linköpings universitet

Hans Gruber

Chalmers, Industri- och materialvetenskap, Material och tillverkning

D. Deng

Linköpings universitet

Ru Lin Peng

Linköpings universitet

JJ Moverare

Linköpings universitet

Acta Materialia

1359-6454 (ISSN)

Vol. 179 142-157



Annan materialteknik

Metallurgi och metalliska material



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