TY  - JOUR
A1  - Nadammal, Naresh
A1  - Mishurova, Tatiana
A1  - Fritsch, Tobias
A1  - Serrano-Munoz, Itziar
A1  - Kromm, Arne
A1  - Haberland, Christoph
A1  - Portella, Pedro Dolabella
A1  - Bruno, Giovanni
T1  - Critical role of scan strategies on the development of microstructure, texture, and residual stresses during laser powder bed fusion additive manufacturing
JF  - Additive manufacturing
N2  - Laser based powder bed fusion additive manufacturing offers the flexibility to incorporate standard and user-defined scan strategies in a layer or in between the layers for the customized fabrication of metallic components. In the present study, four different scan strategies and their impact on the development of microstructure, texture, and residual stresses in laser powder bed fusion additive manufacturing of a nickel-based superalloy Inconel 718 was investigated. Light microscopy, scanning electron microscopy combined with electron back-scatter diffraction, and neutron diffraction were used as the characterization tools. Strong textures with epitaxially grown columnar grains were observed along the build direction for the two individual scan strategies. Patterns depicting the respective scan strategies were visible in the build plane, which dictated the microstructure development in the other planes. An alternating strategy combining the individual strategies in the successive layers and a 67 degrees rotational strategy weakened the texture by forming finer micro-structural features. Von Mises equivalent stress plots revealed lower stress values and gradients, which translates as lower distortions for the alternating and rotational strategies. Overall results confirmed the scope for manipulating the microstructure, texture, and residual stresses during laser powder bed fusion additive manufacturing by effectively controlling the scan strategies.
KW  - Additive manufacturing
KW  - Laser powder bed fusion
KW  - Nickel-based
KW  - superalloys
KW  - Scan strategies
KW  - Residual stresses
KW  - Microstructure and
KW  - texture
Y1  - 2021
U6  - https://doi.org/10.1016/j.addma.2020.101792
SN  - 2214-8604
VL  - 38
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Pauzon, Camille
A1  - Mishurova, Tatiana
A1  - Evsevleev, Sergei
A1  - Dubiez-Le Goff, Sophie
A1  - Murugesan, Saravanakumar
A1  - Bruno, Giovanni
A1  - Hryha, Eduard
T1  - Residual stresses and porosity in Ti-6Al-4V produced by laser powder bed fusion as a function of process atmosphere and component design
JF  - Additive manufacturing
N2  - The influence of the process gas, laser scan speed, and sample thickness on the build-up of residual stresses and porosity in Ti-6Al-4V produced by laser powder bed fusion was studied. Pure argon and helium, as well as a mixture of those (30% helium), were employed to establish process atmospheres with a low residual oxygen content of 100 ppm O-2. The results highlight that the subsurface residual stresses measured by X-ray diffraction were significantly lower in the thin samples (220 MPa) than in the cuboid samples (645 MPa). This difference was attributed to the shorter laser vector length, resulting in heat accumulation and thus in-situ stress relief. The addition of helium to the process gas did not introduce additional subsurface residual stresses in the simple geometries, even for the increased scanning speed. Finally, larger deflection was found in the cantilever built under helium (after removal from the baseplate), than in those produced under argon and an argon-helium mixture. This result demonstrates that complex designs involving large scanned areas could be subjected to higher residual stress when manufactured under helium due to the gas's high thermal conductivity, heat capacity, and thermal diffusivity.
KW  - Residual stresses
KW  - Laser powder bed fusion
KW  - Process atmosphere
KW  - Helium
KW  - Ti-6Al-4V
Y1  - 2021
U6  - https://doi.org/10.1016/j.addma.2021.102340
SN  - 2214-8604
VL  - 47
PB  - Elsevier
CY  - Amsterdam
ER  -