TY  - JOUR
A1  - Mishurova, Tatiana
A1  - Sydow, Benjamin
A1  - Thiede, Tobias
A1  - Sizova, Irina
A1  - Ulbricht, Alexander
A1  - Bambach, Markus
A1  - Bruno, Giovanni
T1  - Residual stress and microstructure of a Ti-6Al-4V Wire Arc Additive Manufacturing hybrid demonstrator
JF  - Metals
N2  - Wire Arc Additive Manufacturing (WAAM) features high deposition rates and, thus, allows production of large components that are relevant for aerospace applications. However, a lot of aerospace parts are currently produced by forging or machining alone to ensure fast production and to obtain good mechanical properties; the use of these conventional process routes causes high tooling and material costs. A hybrid approach (a combination of forging and WAAM) allows making production more efficient. In this fashion, further structural or functional features can be built in any direction without using additional tools for every part. By using a combination of forging basic geometries with one tool set and adding the functional features by means of WAAM, the tool costs and material waste can be reduced compared to either completely forged or machined parts. One of the factors influencing the structural integrity of additively manufactured parts are (high) residual stresses, generated during the build process. In this study, the triaxial residual stress profiles in a hybrid WAAM part are reported, as determined by neutron diffraction. The analysis is complemented by microstructural investigations, showing a gradient of microstructure (shape and size of grains) along the part height. The highest residual stresses were found in the transition zone (between WAAM and forged part). The total stress range showed to be lower than expected for WAAM components. This could be explained by the thermal history of the component.
KW  - residual stress
KW  - WAAM
KW  - Ti-6Al-4V
KW  - additive manufacturing
KW  - neutron
KW  - diffraction
KW  - hybrid manufacturing
Y1  - 2020
U6  - https://doi.org/10.3390/met10060701
SN  - 2075-4701
VL  - 10
IS  - 6
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Serrano-Munoz, Itziar
A1  - Fritsch, Tobias
A1  - Mishurova, Tatiana
A1  - Trofimov, Anton
A1  - Apel, Daniel
A1  - Ulbricht, Alexander
A1  - Kromm, Arne
A1  - Hesse, Rene
A1  - Evans, Alexander
A1  - Bruno, Giovanni
T1  - On the interplay of microstructure and residual stress in LPBF IN718
JF  - Journal of materials science
N2  - The relationship between residual stresses and microstructure associated with a laser powder bed fusion (LPBF) IN718 alloy has been investigated on specimens produced with three different scanning strategies (unidirectional Y-scan, 90 degrees XY-scan, and 67 degrees Rot-scan). Synchrotron X-ray energy-dispersive diffraction (EDXRD) combined with optical profilometry was used to study residual stress (RS) distribution and distortion upon removal of the specimens from the baseplate. The microstructural characterization of both the bulk and the near-surface regions was conducted using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). On the top surfaces of the specimens, the highest RS values are observed in the Y-scan specimen and the lowest in the Rot-scan specimen, while the tendency is inversed on the side lateral surfaces. A considerable amount of RS remains in the specimens after their removal from the baseplate, especially in the Y- and Z-direction (short specimen dimension and building direction (BD), respectively). The distortion measured on the top surface following baseplate thinning and subsequent removal is mainly attributed to the amount of RS released in the build direction. Importantly, it is observed that the additive manufacturing microstructures challenge the use of classic theoretical models for the calculation of diffraction elastic constants (DEC) required for diffraction-based RS analysis. It is found that when the Reuss model is used for the calculation of RS for different crystal planes, as opposed to the conventionally used Kroner model, the results exhibit lower scatter. This is discussed in context of experimental measurements of DEC available in the literature for conventional and additively manufactured Ni-base alloys.
Y1  - 2020
U6  - https://doi.org/10.1007/s10853-020-05553-y
SN  - 0022-2461
SN  - 1573-4803
VL  - 56
IS  - 9
SP  - 5845
EP  - 5867
PB  - Springer
CY  - New York
ER  -