Neutron dark-field imaging applied to porosity and deformation-induced phase transitions in additively manufactured steels

M. Bacak; J. Valsecchi; J. Čapek; E. Polatidis; A. Kaestner; A. Arabi-Hashemi; I. Kruk; C. Leinenbach; A.M. Long; A. Tremsin; S.C. Vogel; E.B. Watkins; M. Strobl

Materials & Design (Oct 2020)

Neutron dark-field imaging applied to porosity and deformation-induced phase transitions in additively manufactured steels

M. Bacak,
J. Valsecchi,
J. Čapek,
E. Polatidis,
A. Kaestner,
A. Arabi-Hashemi,
I. Kruk,
C. Leinenbach,
A.M. Long,
A. Tremsin,
S.C. Vogel,
E.B. Watkins,
M. Strobl

Affiliations

M. Bacak: Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland; Corresponding authors.
J. Valsecchi: Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland; University of Geneva, 1211 Geneva, Switzerland
J. Čapek: Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
E. Polatidis: Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
A. Kaestner: Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
A. Arabi-Hashemi: Empa – Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland
I. Kruk: Los Alamos National Laboratory, Los Alamos, NM 87545, USA
C. Leinenbach: Empa – Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland
A.M. Long: Los Alamos National Laboratory, Los Alamos, NM 87545, USA; Space Sciences Laboratory, University of California at Berkeley, 7 Gauss Way, Berkeley, CA 94720, USA
A. Tremsin: Space Sciences Laboratory, University of California at Berkeley, 7 Gauss Way, Berkeley, CA 94720, USA
S.C. Vogel: Los Alamos National Laboratory, Los Alamos, NM 87545, USA
E.B. Watkins: Los Alamos National Laboratory, Los Alamos, NM 87545, USA
M. Strobl: Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland; Corresponding authors.

Journal volume & issue: Vol. 195
p. 109009

Abstract

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Neutron dark-field imaging (DFI) was used to investigate the microstructure of additive manufactured steels. Several DFI methods were combined to assess the microstructure over more than two orders of magnitude in size. Different degrees of porosity and other building features were found depending on the parameters of the selective laser melting additive manufacturing process. A sample built with processing parameters yielding the lowest porosity was deformed which induced a phase transformation of the austenitic phase (fcc) into the martensitic phase (bcc). In the deformed sample an increased dark-field contrast was observed which can only be explained by accounting for the fcc-bcc phase distribution and the magnetic properties of the martensitic phase. We demonstrate that neutron dark-field imaging is well suited to not only detect build flaws like cracks but quantitatively characterize the microstructure in additive manufactured steels.

Published in Materials & Design

ISSN: 0264-1275 (Print); 1873-4197 (Online)
Publisher: Elsevier
Country of publisher: United Kingdom
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering: Materials of engineering and construction. Mechanics of materials
Website: https://www.journals.elsevier.com/materials-and-design

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