Interfacial characteristics of austenitic 316L and martensitic 15-5PH stainless steels joined by laser powder bed fusion
Interfacial characteristics of austenitic 316L and martensitic 15-5PH stainless steels joined by laser powder bed fusion
Laser powder bed fusion (LPBF) is an additive manufacturing (AM) technology capable of producing complex geometry components from a range of metals and alloys. The static mechanical strength of LPBF manufactured materials can rival that of the equivalent cast and wrought materials, but are more susceptible to fatigue failures due to stress concentrating roughness and porosity defects. The ability to process and join multiple powder materials within a single LPBF build process is an emerging capability that is now becoming commercially available. This new capability offers the possibility of compositional complexity, in addition to the geometric complexity offered by AM, and can help to eliminate the need for additional processing to join different materials. This study focuses on the combination of 316 L austenitic stainless steel (SS) and precipitation hardening 15–5PH martensitic SS by LPBF. The interfacial characteristics and microhardness variation at the interface were investigated by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, and microhardness testing. Good apparent bonding was observed at the interface without any visible cracks or defects. A finer-grain region was observed at a distance of 115 μm below the interface with a grain size of about 25% of that in the surrounding 15–5PH SS. A narrow compositional transition distance of 7 μm along the building direction (less than the 30 μm LPBF layer thickness) and a wavey-morphology interface with an amplitude of about 66 μm (about twice the LPBF layer thickness) were found. A sharp change of hardness was measured within ±200 μm from the interface. Regions far from the interface exhibited similar microstructure and hardness as the corresponding single material components. The results suggest that LPBF joining between 316 L SS and 15–5PH SS can achieve each material's distinct microstructure and properties at far-interface regions, with a narrow wavey region (∼115 μm) at the interface that exhibits high densification and a sharp transition in microstructure and properties.
15–5PH stainless steel, 316 L stainless steel, Interfacial characterization, Joining, Laser powder bed fusion, Multi-material additive manufacture
Liang, Anqi
25257f89-cc17-42b8-81ac-fbf89b37738e
Sahu, Sandeep
ec8fe3c7-0daa-48a6-96bd-a7d55397f94a
Zhao, Xiao
de2d3aaf-e6b7-469e-a747-fbe5f64d36e9
Polcar, Tomas
c669b663-3ba9-4e7b-9f97-8ef5655ac6d2
Hamilton, Andrew
9088cf01-8d7f-45f0-af56-b4784227447c
April 2023
Liang, Anqi
25257f89-cc17-42b8-81ac-fbf89b37738e
Sahu, Sandeep
ec8fe3c7-0daa-48a6-96bd-a7d55397f94a
Zhao, Xiao
de2d3aaf-e6b7-469e-a747-fbe5f64d36e9
Polcar, Tomas
c669b663-3ba9-4e7b-9f97-8ef5655ac6d2
Hamilton, Andrew
9088cf01-8d7f-45f0-af56-b4784227447c
Liang, Anqi, Sahu, Sandeep, Zhao, Xiao, Polcar, Tomas and Hamilton, Andrew
(2023)
Interfacial characteristics of austenitic 316L and martensitic 15-5PH stainless steels joined by laser powder bed fusion.
Materials Characterization, 198, [112719].
(doi:10.1016/j.matchar.2023.112719).
Abstract
Laser powder bed fusion (LPBF) is an additive manufacturing (AM) technology capable of producing complex geometry components from a range of metals and alloys. The static mechanical strength of LPBF manufactured materials can rival that of the equivalent cast and wrought materials, but are more susceptible to fatigue failures due to stress concentrating roughness and porosity defects. The ability to process and join multiple powder materials within a single LPBF build process is an emerging capability that is now becoming commercially available. This new capability offers the possibility of compositional complexity, in addition to the geometric complexity offered by AM, and can help to eliminate the need for additional processing to join different materials. This study focuses on the combination of 316 L austenitic stainless steel (SS) and precipitation hardening 15–5PH martensitic SS by LPBF. The interfacial characteristics and microhardness variation at the interface were investigated by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, and microhardness testing. Good apparent bonding was observed at the interface without any visible cracks or defects. A finer-grain region was observed at a distance of 115 μm below the interface with a grain size of about 25% of that in the surrounding 15–5PH SS. A narrow compositional transition distance of 7 μm along the building direction (less than the 30 μm LPBF layer thickness) and a wavey-morphology interface with an amplitude of about 66 μm (about twice the LPBF layer thickness) were found. A sharp change of hardness was measured within ±200 μm from the interface. Regions far from the interface exhibited similar microstructure and hardness as the corresponding single material components. The results suggest that LPBF joining between 316 L SS and 15–5PH SS can achieve each material's distinct microstructure and properties at far-interface regions, with a narrow wavey region (∼115 μm) at the interface that exhibits high densification and a sharp transition in microstructure and properties.
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Accepted/In Press date: 3 February 2023
e-pub ahead of print date: 8 February 2023
Published date: April 2023
Additional Information:
Funding Information:
SS thankfully acknowledges the Royal Society for providing Newton International Fellowship NIF\R1\201789 .
Funding Information:
This work was supported by the Faculty of Engineering and Physical Science at University of Southampton .
Publisher Copyright:
© 2023
Keywords:
15–5PH stainless steel, 316 L stainless steel, Interfacial characterization, Joining, Laser powder bed fusion, Multi-material additive manufacture
Identifiers
Local EPrints ID: 476786
URI: http://eprints.soton.ac.uk/id/eprint/476786
ISSN: 1044-5803
PURE UUID: 1a29bed0-8c52-42be-96a1-96efc7405b6c
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Date deposited: 16 May 2023 16:33
Last modified: 06 Jun 2024 01:59
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Author:
Anqi Liang
Author:
Sandeep Sahu
Author:
Xiao Zhao
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