Texture evolution as a function of scan strategy and build height in electron beam melted Ti-6Al-4V

Alec I. Saville; Sven C. Vogel; Adam Creuziger; Jake T. Benzing; Adam L. Pilchak; Peeyush Nandwana; Jonah Klemm-Toole; Kester D. Clarke; S. Lee Semiatin; Amy J. Clarke

doi:10.1016/j.addma.2021.102118

Texture evolution as a function of scan strategy and build height in electron beam melted Ti-6Al-4V

Alec I. Saville, Sven C. Vogel, Adam Creuziger, Jake T. Benzing, Adam L. Pilchak, Peeyush Nandwana, Jonah Klemm-Toole, Kester D. Clarke, S. Lee Semiatin, Amy J. Clarke

Research output: Contribution to journal › Article › peer-review

33 Scopus citations

Abstract

Metal additive manufacturing (AM) enables customizable, on-demand parts, allowing for new designs and improved engineering performance. Yet, the ability to control AM metal alloy microstructures (i.e., grain morphology, crystallographic texture, and phase content) is lacking. This work performs corroborative neutron diffraction and large-scale electron backscatter diffraction (EBSD) measurements to assess crystallographic texture in electron beam melted (EBM) Ti-6Al-4V as a function of scan strategy and build height. Texture components for one raster and two spot melt scan strategies were evaluated using a triclinic specimen symmetry to capture all possible texture components, which were found to be considerably different than previously reported values from studies employing orthotropic specimen symmetry. This finding highlights the importance of a standard method and best practice for assessing textures produced by AM. Texture was found to vary between scan strategies, but changed minimally as a function of build height. Parent phase β-Ti reconstructions obtained from as-built crystallographic orientations revealed spot melt scan strategies produced finer equiaxed/columnar grains with clear {001}_β build direction fiber textures, whereas the raster scan strategy produced large columnar grains and a weaker {001}_β build direction fiber texture. The observed grain morphologies agree with those predicted by solidification theory for the thermal gradients and solidification velocities experienced during the build process. The presence of a strong {001}_β fiber orientation (typical of cubic solidification) produced by spot melting was found to correlate with a previously unreported {011̅2}_α fiber texture in the as-built condition and colony microstructures. The {011̅2}_α fiber texture was weakly observed for the raster scan strategy, and {001}_β oriented grains preferentially transformed into α′ martensite with orientations between {11̅00}_α and {112̅0}_α. This shift in product α-Ti orientations has not yet been reported, and further work is recommended to understand these crystallographic signatures in the context of solid-state phase transformations. The presence of the {011̅2}_α fiber texture is proposed as a useful diagnostic for evaluating the solidification or transformed microstructure condition (e.g., grain morphology and texture) of Ti-6Al-4V AM builds via accessible techniques like laboratory X-ray diffraction.

Original language	English
Article number	102118
Journal	Additive Manufacturing
Volume	46
DOIs	https://doi.org/10.1016/j.addma.2021.102118
State	Published - Oct 2021
Externally published	Yes

Funding

These experiments, AIS (partial support), PN, JKT, and AJC were supported by the Department of the Navy , USA, Office of Naval Research , USA, under ONR award number N00014-18-1-2794 . Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Office of Naval Research. AIS (partial support), data analysis and the preparation of this manuscript were supported by the National Science Foundation Graduate Research Fellowship , USA, under Grant No. 2019260337 . KDC thanks the Center for Advanced Non-Ferrous Structural Alloys (CANFSA), USA, a National Science Foundation Industry/University Cooperative Research Center (I/UCRC), USA, [Award No. 1624836 ] at the Colorado School of Mines (Mines), USA, during the preparation of this manuscript. Neutron diffraction measurements were supported by the Los Alamos Neutron Science Center (LANSCE), a NNSA User Facility operated for the US Department of Energy (DOE) by Los Alamos National Laboratory (LANL). LANL is operated by Triad National Security, LLC, for the National Nuclear Security Administration , USA, of US DOE (Contract No. 89233218CNA000001 ). AC and JTB acknowledge the support of the National Institute of Standards and Technology , USA, US Department of Commerce , USA, in obtaining the large-scale EBSD and during data analysis. AIS would also like to thank Ralf Hieschler, Rüdiger Kilian, and the rest of the MTEX team for their help in using MTEX for this work. The authors also gratefully acknowledge Chase Joslin and James Ferguson for producing the samples tested here, in addition to Sabina Kumar at the University of Tennessee Knoxville for facilitating sample preparation and running the thermal simulations for each scan strategy explored. Access to the Oak Ridge National Laboratory’s (ORNL) additive manufacturing equipment at ORNL’s Manufacturing Demonstration Facility (MDF) was facilitated by US DOE’s Strategic Partnership Projects (SPP) mechanism. More information can be found at https://science.energy.gov/lp/strategic-partnership-projects . Research sponsored by the US DOE , Office of Energy Efficiency and Renewable Energy , USA, Industrial Technologies Program , USA, under contract DE-AC05-00OR22725 with UT-Battelle, LLC. These experiments, AIS (partial support), PN, JKT, and AJC were supported by the Department of the Navy, USA, Office of Naval Research, USA, under ONR award number N00014-18-1-2794. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Office of Naval Research. AIS (partial support), data analysis and the preparation of this manuscript were supported by the National Science Foundation Graduate Research Fellowship, USA, under Grant No. 2019260337. KDC thanks the Center for Advanced Non-Ferrous Structural Alloys (CANFSA), USA, a National Science Foundation Industry/University Cooperative Research Center (I/UCRC), USA, [Award No. 1624836] at the Colorado School of Mines (Mines), USA, during the preparation of this manuscript. Neutron diffraction measurements were supported by the Los Alamos Neutron Science Center (LANSCE), a NNSA User Facility operated for the US Department of Energy (DOE) by Los Alamos National Laboratory (LANL). LANL is operated by Triad National Security, LLC, for the National Nuclear Security Administration, USA, of US DOE (Contract No. 89233218CNA000001). AC and JTB acknowledge the support of the National Institute of Standards and Technology, USA, US Department of Commerce, USA, in obtaining the large-scale EBSD and during data analysis. AIS would also like to thank Ralf Hieschler, R?diger Kilian, and the rest of the MTEX team for their help in using MTEX for this work. The authors also gratefully acknowledge Chase Joslin and James Ferguson for producing the samples tested here, in addition to Sabina Kumar at the University of Tennessee Knoxville for facilitating sample preparation and running the thermal simulations for each scan strategy explored. Access to the Oak Ridge National Laboratory's (ORNL) additive manufacturing equipment at ORNL's Manufacturing Demonstration Facility (MDF) was facilitated by US DOE's Strategic Partnership Projects (SPP) mechanism. More information can be found at https://science.energy.gov/lp/strategic-partnership-projects. Research sponsored by the US DOE, Office of Energy Efficiency and Renewable Energy, USA, Industrial Technologies Program, USA, under contract DE-AC05-00OR22725 with UT-Battelle, LLC.

Keywords

Beta-Ti
Crystallographic texture
Reconstructions
Scan strategy
Solidification and solidification modelling
Ti-6Al-4V

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.addma.2021.102118

Cite this

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title = "Texture evolution as a function of scan strategy and build height in electron beam melted Ti-6Al-4V",

abstract = "Metal additive manufacturing (AM) enables customizable, on-demand parts, allowing for new designs and improved engineering performance. Yet, the ability to control AM metal alloy microstructures (i.e., grain morphology, crystallographic texture, and phase content) is lacking. This work performs corroborative neutron diffraction and large-scale electron backscatter diffraction (EBSD) measurements to assess crystallographic texture in electron beam melted (EBM) Ti-6Al-4V as a function of scan strategy and build height. Texture components for one raster and two spot melt scan strategies were evaluated using a triclinic specimen symmetry to capture all possible texture components, which were found to be considerably different than previously reported values from studies employing orthotropic specimen symmetry. This finding highlights the importance of a standard method and best practice for assessing textures produced by AM. Texture was found to vary between scan strategies, but changed minimally as a function of build height. Parent phase β-Ti reconstructions obtained from as-built crystallographic orientations revealed spot melt scan strategies produced finer equiaxed/columnar grains with clear {001}β build direction fiber textures, whereas the raster scan strategy produced large columnar grains and a weaker {001}β build direction fiber texture. The observed grain morphologies agree with those predicted by solidification theory for the thermal gradients and solidification velocities experienced during the build process. The presence of a strong {001}β fiber orientation (typical of cubic solidification) produced by spot melting was found to correlate with a previously unreported {011̅2}α fiber texture in the as-built condition and colony microstructures. The {011̅2}α fiber texture was weakly observed for the raster scan strategy, and {001}β oriented grains preferentially transformed into α′ martensite with orientations between {11̅00}α and {112̅0}α. This shift in product α-Ti orientations has not yet been reported, and further work is recommended to understand these crystallographic signatures in the context of solid-state phase transformations. The presence of the {011̅2}α fiber texture is proposed as a useful diagnostic for evaluating the solidification or transformed microstructure condition (e.g., grain morphology and texture) of Ti-6Al-4V AM builds via accessible techniques like laboratory X-ray diffraction.",

keywords = "Beta-Ti, Crystallographic texture, Reconstructions, Scan strategy, Solidification and solidification modelling, Ti-6Al-4V",

author = "Saville, {Alec I.} and Vogel, {Sven C.} and Adam Creuziger and Benzing, {Jake T.} and Pilchak, {Adam L.} and Peeyush Nandwana and Jonah Klemm-Toole and Clarke, {Kester D.} and Semiatin, {S. Lee} and Clarke, {Amy J.}",

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doi = "10.1016/j.addma.2021.102118",

language = "English",

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AU - Saville, Alec I.

AU - Vogel, Sven C.

AU - Creuziger, Adam

AU - Benzing, Jake T.

AU - Pilchak, Adam L.

AU - Nandwana, Peeyush

AU - Klemm-Toole, Jonah

AU - Clarke, Kester D.

AU - Semiatin, S. Lee

AU - Clarke, Amy J.

PY - 2021/10

Y1 - 2021/10

N2 - Metal additive manufacturing (AM) enables customizable, on-demand parts, allowing for new designs and improved engineering performance. Yet, the ability to control AM metal alloy microstructures (i.e., grain morphology, crystallographic texture, and phase content) is lacking. This work performs corroborative neutron diffraction and large-scale electron backscatter diffraction (EBSD) measurements to assess crystallographic texture in electron beam melted (EBM) Ti-6Al-4V as a function of scan strategy and build height. Texture components for one raster and two spot melt scan strategies were evaluated using a triclinic specimen symmetry to capture all possible texture components, which were found to be considerably different than previously reported values from studies employing orthotropic specimen symmetry. This finding highlights the importance of a standard method and best practice for assessing textures produced by AM. Texture was found to vary between scan strategies, but changed minimally as a function of build height. Parent phase β-Ti reconstructions obtained from as-built crystallographic orientations revealed spot melt scan strategies produced finer equiaxed/columnar grains with clear {001}β build direction fiber textures, whereas the raster scan strategy produced large columnar grains and a weaker {001}β build direction fiber texture. The observed grain morphologies agree with those predicted by solidification theory for the thermal gradients and solidification velocities experienced during the build process. The presence of a strong {001}β fiber orientation (typical of cubic solidification) produced by spot melting was found to correlate with a previously unreported {011̅2}α fiber texture in the as-built condition and colony microstructures. The {011̅2}α fiber texture was weakly observed for the raster scan strategy, and {001}β oriented grains preferentially transformed into α′ martensite with orientations between {11̅00}α and {112̅0}α. This shift in product α-Ti orientations has not yet been reported, and further work is recommended to understand these crystallographic signatures in the context of solid-state phase transformations. The presence of the {011̅2}α fiber texture is proposed as a useful diagnostic for evaluating the solidification or transformed microstructure condition (e.g., grain morphology and texture) of Ti-6Al-4V AM builds via accessible techniques like laboratory X-ray diffraction.

AB - Metal additive manufacturing (AM) enables customizable, on-demand parts, allowing for new designs and improved engineering performance. Yet, the ability to control AM metal alloy microstructures (i.e., grain morphology, crystallographic texture, and phase content) is lacking. This work performs corroborative neutron diffraction and large-scale electron backscatter diffraction (EBSD) measurements to assess crystallographic texture in electron beam melted (EBM) Ti-6Al-4V as a function of scan strategy and build height. Texture components for one raster and two spot melt scan strategies were evaluated using a triclinic specimen symmetry to capture all possible texture components, which were found to be considerably different than previously reported values from studies employing orthotropic specimen symmetry. This finding highlights the importance of a standard method and best practice for assessing textures produced by AM. Texture was found to vary between scan strategies, but changed minimally as a function of build height. Parent phase β-Ti reconstructions obtained from as-built crystallographic orientations revealed spot melt scan strategies produced finer equiaxed/columnar grains with clear {001}β build direction fiber textures, whereas the raster scan strategy produced large columnar grains and a weaker {001}β build direction fiber texture. The observed grain morphologies agree with those predicted by solidification theory for the thermal gradients and solidification velocities experienced during the build process. The presence of a strong {001}β fiber orientation (typical of cubic solidification) produced by spot melting was found to correlate with a previously unreported {011̅2}α fiber texture in the as-built condition and colony microstructures. The {011̅2}α fiber texture was weakly observed for the raster scan strategy, and {001}β oriented grains preferentially transformed into α′ martensite with orientations between {11̅00}α and {112̅0}α. This shift in product α-Ti orientations has not yet been reported, and further work is recommended to understand these crystallographic signatures in the context of solid-state phase transformations. The presence of the {011̅2}α fiber texture is proposed as a useful diagnostic for evaluating the solidification or transformed microstructure condition (e.g., grain morphology and texture) of Ti-6Al-4V AM builds via accessible techniques like laboratory X-ray diffraction.

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Texture evolution as a function of scan strategy and build height in electron beam melted Ti-6Al-4V

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Keywords

UN SDGs

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