A Comparative Investigation of Duplex and Super Duplex Stainless Steels Processed through Laser Powder Bed Fusion
The aim of this paper was to compare duplex (DSS) and super duplex stainless steel processed by laser powder bed fusion (LPBF) based on the process parameters and microstructure–nanomechanical property relationships. Each alloy was investigated with respect to its feedstock powder characteristics. O...
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MDPI AG
2023-11-01
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| Series: | Metals |
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| Online Access: | https://www.mdpi.com/2075-4701/13/11/1897 |
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| author | Leonidas Gargalis Leonidas Karavias Joachim S. Graff Spyros Diplas Elias P. Koumoulos Evangelia K. Karaxi |
| author_facet | Leonidas Gargalis Leonidas Karavias Joachim S. Graff Spyros Diplas Elias P. Koumoulos Evangelia K. Karaxi |
| author_sort | Leonidas Gargalis |
| collection | DOAJ |
| description | The aim of this paper was to compare duplex (DSS) and super duplex stainless steel processed by laser powder bed fusion (LPBF) based on the process parameters and microstructure–nanomechanical property relationships. Each alloy was investigated with respect to its feedstock powder characteristics. Optimum process parameters including scanning speed, laser power, beam diameter, laser energy density, and layer thickness were defined for each alloy, and near-fully dense parts (>99.9%) were produced. Microstructural analysis was performed via optical (OM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The samples were subjected to stress relief and high-temperature annealing. EBSD revealed the crystallographic orientation and quantified the phases in the as-built and annealed sample conditions. The as-built samples revealed a fully ferritic microstructure with a small amount of grain boundary austenite in the SDSS microstructure. High-temperature solution annealing resulted in the desired duplex microstructure for both alloys. There were no secondary phases present in the microstructure after both heat treatments. Nanoindentation generated nanomechanical (modulus) mapping grids and quantified the nanomechanical (both hardness and modulus) response; plasticity and stress relief were also assessed in all three conditions (as-built, stress-relieved, and annealed) in both DSS and SDSS. Austenite formation in the annealed condition contributed to lower hardness levels (~4.3–4.8 Gpa) and higher plastic deformation compared to the as-built (~5.7–6.3 Gpa) and stress-relieved conditions (~4.8–5.8 Gpa) for both alloys. SDSS featured a ~60% austenite volume fraction in its annealed and quenched microstructure, attributed to its higher nickel and nitrogen contents compared to DSS, which exhibited a ~30% austenite volume fraction. |
| first_indexed | 2024-03-09T16:36:30Z |
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| issn | 2075-4701 |
| language | English |
| last_indexed | 2024-03-09T16:36:30Z |
| publishDate | 2023-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Metals |
| spelling | doaj.art-b4693aa589104617a044fc4801a823b62023-11-24T14:56:00ZengMDPI AGMetals2075-47012023-11-011311189710.3390/met13111897A Comparative Investigation of Duplex and Super Duplex Stainless Steels Processed through Laser Powder Bed FusionLeonidas Gargalis0Leonidas Karavias1Joachim S. Graff2Spyros Diplas3Elias P. Koumoulos4Evangelia K. Karaxi5Conify, Lavrion Ave.1, Lavrion Technological and Cultural Park (LTCP), 19500 Lavrion, GreeceConify, Lavrion Ave.1, Lavrion Technological and Cultural Park (LTCP), 19500 Lavrion, GreeceSINTEF Industry, Forskningsveien 1, 0373 Oslo, NorwaySINTEF Industry, Forskningsveien 1, 0373 Oslo, NorwayIRES—Innovation in Research & Engineering Solutions, Rue Koningin Astritlaan 59B, 1780 Wemmel, BelgiumConify, Lavrion Ave.1, Lavrion Technological and Cultural Park (LTCP), 19500 Lavrion, GreeceThe aim of this paper was to compare duplex (DSS) and super duplex stainless steel processed by laser powder bed fusion (LPBF) based on the process parameters and microstructure–nanomechanical property relationships. Each alloy was investigated with respect to its feedstock powder characteristics. Optimum process parameters including scanning speed, laser power, beam diameter, laser energy density, and layer thickness were defined for each alloy, and near-fully dense parts (>99.9%) were produced. Microstructural analysis was performed via optical (OM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The samples were subjected to stress relief and high-temperature annealing. EBSD revealed the crystallographic orientation and quantified the phases in the as-built and annealed sample conditions. The as-built samples revealed a fully ferritic microstructure with a small amount of grain boundary austenite in the SDSS microstructure. High-temperature solution annealing resulted in the desired duplex microstructure for both alloys. There were no secondary phases present in the microstructure after both heat treatments. Nanoindentation generated nanomechanical (modulus) mapping grids and quantified the nanomechanical (both hardness and modulus) response; plasticity and stress relief were also assessed in all three conditions (as-built, stress-relieved, and annealed) in both DSS and SDSS. Austenite formation in the annealed condition contributed to lower hardness levels (~4.3–4.8 Gpa) and higher plastic deformation compared to the as-built (~5.7–6.3 Gpa) and stress-relieved conditions (~4.8–5.8 Gpa) for both alloys. SDSS featured a ~60% austenite volume fraction in its annealed and quenched microstructure, attributed to its higher nickel and nitrogen contents compared to DSS, which exhibited a ~30% austenite volume fraction.https://www.mdpi.com/2075-4701/13/11/1897duplex stainless steelsuper duplex stainless steelelectron backscatter diffractionnanoindentationlaser powder bed fusionadditive manufacturing |
| spellingShingle | Leonidas Gargalis Leonidas Karavias Joachim S. Graff Spyros Diplas Elias P. Koumoulos Evangelia K. Karaxi A Comparative Investigation of Duplex and Super Duplex Stainless Steels Processed through Laser Powder Bed Fusion Metals duplex stainless steel super duplex stainless steel electron backscatter diffraction nanoindentation laser powder bed fusion additive manufacturing |
| title | A Comparative Investigation of Duplex and Super Duplex Stainless Steels Processed through Laser Powder Bed Fusion |
| title_full | A Comparative Investigation of Duplex and Super Duplex Stainless Steels Processed through Laser Powder Bed Fusion |
| title_fullStr | A Comparative Investigation of Duplex and Super Duplex Stainless Steels Processed through Laser Powder Bed Fusion |
| title_full_unstemmed | A Comparative Investigation of Duplex and Super Duplex Stainless Steels Processed through Laser Powder Bed Fusion |
| title_short | A Comparative Investigation of Duplex and Super Duplex Stainless Steels Processed through Laser Powder Bed Fusion |
| title_sort | comparative investigation of duplex and super duplex stainless steels processed through laser powder bed fusion |
| topic | duplex stainless steel super duplex stainless steel electron backscatter diffraction nanoindentation laser powder bed fusion additive manufacturing |
| url | https://www.mdpi.com/2075-4701/13/11/1897 |
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