Stacking Fault Energy in Relation to Hydrogen Environment Embrittlement of Metastable Austenitic Stainless CrNi-Steels
Metastable austenitic steels react to plastic deformation with a thermally and/or mechanically induced martensitic phase transformation. The martensitic transformation to α’-martensite can take place directly or indirectly via the intermediate stage of ε-martensite from the single-phase austenite. T...
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MDPI AG
2021-07-01
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| Online Access: | https://www.mdpi.com/2075-4701/11/8/1170 |
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| author | Robert Fussik Gero Egels Werner Theisen Sebastian Weber |
| author_facet | Robert Fussik Gero Egels Werner Theisen Sebastian Weber |
| author_sort | Robert Fussik |
| collection | DOAJ |
| description | Metastable austenitic steels react to plastic deformation with a thermally and/or mechanically induced martensitic phase transformation. The martensitic transformation to α’-martensite can take place directly or indirectly via the intermediate stage of ε-martensite from the single-phase austenite. This effect is influenced by the stacking fault energy (SFE) of austenitic steels. An SFE < 20 mJ/m<sup>2</sup> is known to promote indirect conversion, while an SFE > 20 mJ/m<sup>2</sup> promotes the direct conversion of austenite into α’-martensite. This relationship has thus far not been considered in relation to the hydrogen environment embrittlement (HEE) of metastable austenitic CrNi steels. To gain new insights into HEE under consideration of the SFE and martensite formation of metastable CrNi steels, tensile tests were carried out in this study at room temperature in an air environment and in a hydrogen gas atmosphere with a pressure of p = 10 MPa. These tests were conducted on a conventionally produced alloy AISI 304L and a laboratory-scale modification of this alloy. In terms of metal physics, the steels under consideration differed in the value of the experimentally determined SFE. The SFE of the AISI 304L was 22.7 ± 0.8 mJ/m<sup>2</sup> and the SFE of the 304 mod alloy was 18.7 ± 0.4 mJ/m<sup>2</sup>. The tensile specimens tested in air revealed a direct γ → α’ conversion for AISI 304L and an indirect γ → ε → α’ conversion for 304 mod. From the results it could be deduced that the indirect phase transformation is responsible for a significant increase in the content of deformation-induced α’-martensite due to a reduction of the SFE value below 20 mJ/m<sup>2</sup> in hydrogen gas atmosphere. |
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| spelling | doaj.art-1ff1dd941123421c863bc9de1f3c22f92023-11-22T08:40:27ZengMDPI AGMetals2075-47012021-07-01118117010.3390/met11081170Stacking Fault Energy in Relation to Hydrogen Environment Embrittlement of Metastable Austenitic Stainless CrNi-SteelsRobert Fussik0Gero Egels1Werner Theisen2Sebastian Weber3Lehrstuhl für Neue Fertigungstechnologien und Werkstoffe, Bergische Universität Wuppertal, 42651 Solingen, GermanyLehrstuhl Werkstofftechnik, Institut für Werkstoffe, Ruhr-Universität Bochum, 44780 Bochum, GermanyLehrstuhl Werkstofftechnik, Institut für Werkstoffe, Ruhr-Universität Bochum, 44780 Bochum, GermanyLehrstuhl Werkstofftechnik, Institut für Werkstoffe, Ruhr-Universität Bochum, 44780 Bochum, GermanyMetastable austenitic steels react to plastic deformation with a thermally and/or mechanically induced martensitic phase transformation. The martensitic transformation to α’-martensite can take place directly or indirectly via the intermediate stage of ε-martensite from the single-phase austenite. This effect is influenced by the stacking fault energy (SFE) of austenitic steels. An SFE < 20 mJ/m<sup>2</sup> is known to promote indirect conversion, while an SFE > 20 mJ/m<sup>2</sup> promotes the direct conversion of austenite into α’-martensite. This relationship has thus far not been considered in relation to the hydrogen environment embrittlement (HEE) of metastable austenitic CrNi steels. To gain new insights into HEE under consideration of the SFE and martensite formation of metastable CrNi steels, tensile tests were carried out in this study at room temperature in an air environment and in a hydrogen gas atmosphere with a pressure of p = 10 MPa. These tests were conducted on a conventionally produced alloy AISI 304L and a laboratory-scale modification of this alloy. In terms of metal physics, the steels under consideration differed in the value of the experimentally determined SFE. The SFE of the AISI 304L was 22.7 ± 0.8 mJ/m<sup>2</sup> and the SFE of the 304 mod alloy was 18.7 ± 0.4 mJ/m<sup>2</sup>. The tensile specimens tested in air revealed a direct γ → α’ conversion for AISI 304L and an indirect γ → ε → α’ conversion for 304 mod. From the results it could be deduced that the indirect phase transformation is responsible for a significant increase in the content of deformation-induced α’-martensite due to a reduction of the SFE value below 20 mJ/m<sup>2</sup> in hydrogen gas atmosphere.https://www.mdpi.com/2075-4701/11/8/1170hydrogen environment embrittlementmetastable austenitic stainless steelstacking fault energydeformation modesaustenite stability |
| spellingShingle | Robert Fussik Gero Egels Werner Theisen Sebastian Weber Stacking Fault Energy in Relation to Hydrogen Environment Embrittlement of Metastable Austenitic Stainless CrNi-Steels Metals hydrogen environment embrittlement metastable austenitic stainless steel stacking fault energy deformation modes austenite stability |
| title | Stacking Fault Energy in Relation to Hydrogen Environment Embrittlement of Metastable Austenitic Stainless CrNi-Steels |
| title_full | Stacking Fault Energy in Relation to Hydrogen Environment Embrittlement of Metastable Austenitic Stainless CrNi-Steels |
| title_fullStr | Stacking Fault Energy in Relation to Hydrogen Environment Embrittlement of Metastable Austenitic Stainless CrNi-Steels |
| title_full_unstemmed | Stacking Fault Energy in Relation to Hydrogen Environment Embrittlement of Metastable Austenitic Stainless CrNi-Steels |
| title_short | Stacking Fault Energy in Relation to Hydrogen Environment Embrittlement of Metastable Austenitic Stainless CrNi-Steels |
| title_sort | stacking fault energy in relation to hydrogen environment embrittlement of metastable austenitic stainless crni steels |
| topic | hydrogen environment embrittlement metastable austenitic stainless steel stacking fault energy deformation modes austenite stability |
| url | https://www.mdpi.com/2075-4701/11/8/1170 |
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