date: 2016-12-24T06:38:09Z
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pdf:docinfo:title: Comparison of Maraging Steel Micro- and Nanostructure Produced Conventionally and by Laser Additive Manufacturing
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subject: Maraging steels are used to produce tools by Additive Manufacturing (AM) methods such as Laser Metal Deposition (LMD) and Selective Laser Melting (SLM). Although it is well established that dense parts can be produced by AM, the influence of the AM process on the microstructure?in particular the content of retained and reversed austenite as well as the nanostructure, especially the precipitate density and chemistry, are not yet explored. Here, we study these features using microhardness measurements, Optical Microscopy, Electron Backscatter Diffraction (EBSD), Energy Dispersive Spectroscopy (EDS), and Atom Probe Tomography (APT) in the as-produced state and during ageing heat treatment. We find that due to microsegregation, retained austenite exists in the as-LMD- and as-SLM-produced states but not in the conventionally-produced material. The hardness in the as-LMD-produced state is higher than in the conventionally and SLM-produced materials, however, not in the uppermost layers. By APT, it is confirmed that this is due to early stages of precipitation induced by the cyclic re-heating upon further deposition?i.e., the intrinsic heat treatment associated with LMD. In the peak-aged state, which is reached after a similar time in all materials, the hardness of SLM- and LMD-produced material is slightly lower than in conventionally-produced material due to the presence of retained austenite and reversed austenite formed during ageing.
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dc:title: Comparison of Maraging Steel Micro- and Nanostructure Produced Conventionally and by Laser Additive Manufacturing
modified: 2016-12-24T06:38:09Z
cp:subject: Maraging steels are used to produce tools by Additive Manufacturing (AM) methods such as Laser Metal Deposition (LMD) and Selective Laser Melting (SLM). Although it is well established that dense parts can be produced by AM, the influence of the AM process on the microstructure?in particular the content of retained and reversed austenite as well as the nanostructure, especially the precipitate density and chemistry, are not yet explored. Here, we study these features using microhardness measurements, Optical Microscopy, Electron Backscatter Diffraction (EBSD), Energy Dispersive Spectroscopy (EDS), and Atom Probe Tomography (APT) in the as-produced state and during ageing heat treatment. We find that due to microsegregation, retained austenite exists in the as-LMD- and as-SLM-produced states but not in the conventionally-produced material. The hardness in the as-LMD-produced state is higher than in the conventionally and SLM-produced materials, however, not in the uppermost layers. By APT, it is confirmed that this is due to early stages of precipitation induced by the cyclic re-heating upon further deposition?i.e., the intrinsic heat treatment associated with LMD. In the peak-aged state, which is reached after a similar time in all materials, the hardness of SLM- and LMD-produced material is slightly lower than in conventionally-produced material due to the presence of retained austenite and reversed austenite formed during ageing.
pdf:docinfo:subject: Maraging steels are used to produce tools by Additive Manufacturing (AM) methods such as Laser Metal Deposition (LMD) and Selective Laser Melting (SLM). Although it is well established that dense parts can be produced by AM, the influence of the AM process on the microstructure?in particular the content of retained and reversed austenite as well as the nanostructure, especially the precipitate density and chemistry, are not yet explored. Here, we study these features using microhardness measurements, Optical Microscopy, Electron Backscatter Diffraction (EBSD), Energy Dispersive Spectroscopy (EDS), and Atom Probe Tomography (APT) in the as-produced state and during ageing heat treatment. We find that due to microsegregation, retained austenite exists in the as-LMD- and as-SLM-produced states but not in the conventionally-produced material. The hardness in the as-LMD-produced state is higher than in the conventionally and SLM-produced materials, however, not in the uppermost layers. By APT, it is confirmed that this is due to early stages of precipitation induced by the cyclic re-heating upon further deposition?i.e., the intrinsic heat treatment associated with LMD. In the peak-aged state, which is reached after a similar time in all materials, the hardness of SLM- and LMD-produced material is slightly lower than in conventionally-produced material due to the presence of retained austenite and reversed austenite formed during ageing.
pdf:docinfo:creator: Eric A. Jägle, Zhendong Sheng, Philipp Kürnsteiner, Sörn Ocylok, Andreas Weisheit and Dierk Raabe
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Author: Eric A. Jägle, Zhendong Sheng, Philipp Kürnsteiner, Sörn Ocylok, Andreas Weisheit and Dierk Raabe
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Keywords: laser metal deposition; additive manufacturing; maraging steel; intrinsic heat treatment; precipitation strengthening; austenite reversion; atom probe tomography
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dc:creator: Eric A. Jägle, Zhendong Sheng, Philipp Kürnsteiner, Sörn Ocylok, Andreas Weisheit and Dierk Raabe
dcterms:created: 2016-12-24T06:38:09Z
Last-Modified: 2016-12-24T06:38:09Z
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title: Comparison of Maraging Steel Micro- and Nanostructure Produced Conventionally and by Laser Additive Manufacturing
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pdf:docinfo:keywords: laser metal deposition; additive manufacturing; maraging steel; intrinsic heat treatment; precipitation strengthening; austenite reversion; atom probe tomography
pdf:docinfo:modified: 2016-12-24T06:38:09Z
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creator: Eric A. Jägle, Zhendong Sheng, Philipp Kürnsteiner, Sörn Ocylok, Andreas Weisheit and Dierk Raabe
dc:subject: laser metal deposition; additive manufacturing; maraging steel; intrinsic heat treatment; precipitation strengthening; austenite reversion; atom probe tomography
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meta:keyword: laser metal deposition; additive manufacturing; maraging steel; intrinsic heat treatment; precipitation strengthening; austenite reversion; atom probe tomography
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pdf:docinfo:created: 2016-12-24T06:38:09Z