Deformation Induced Soft and Hard Lath Packets Enhance Ductility in Martensitic Steels
Martensitic steels are widely used structural materials with outstanding mechanical properties. Their high strength is provided by the non-diffusional phase transformation of <i>fcc</i> γ into thin lamellar <i>bcc</i> plates during fast cooling. Coherency strains between the...
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MDPI AG
2020-05-01
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| Series: | Crystals |
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| Online Access: | https://www.mdpi.com/2073-4352/10/5/373 |
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| author | Éva Ódor Bertalan Jóni Gábor Ribárik Nguyen Quang Chinh Tamás Ungár Péter J. Szabó |
| author_facet | Éva Ódor Bertalan Jóni Gábor Ribárik Nguyen Quang Chinh Tamás Ungár Péter J. Szabó |
| author_sort | Éva Ódor |
| collection | DOAJ |
| description | Martensitic steels are widely used structural materials with outstanding mechanical properties. Their high strength is provided by the non-diffusional phase transformation of <i>fcc</i> γ into thin lamellar <i>bcc</i> plates during fast cooling. Coherency strains between the <i>fcc</i> and <i>bcc</i> lamellae induce large dislocation densities in the range of 10<sup>16</sup> m<sup>−2</sup>, well above the densities attainable by conventional plastic deformation. Using high resolution X-ray line profile analysis, scanning electron microscopy, and hardness tests we show that during tensile deformation when the active Burgers vectors are within the lath plane the lath-packets work soften. On the contrary, when the active Burgers vectors are oblique to the lath-plane the lath-packets work harden. The softening and hardening processes in the differently oriented lath-packets produce a composite of hard and soft components on the length scale of lath-packet size. The stress–strain response of the alloy is discussed in terms of the different mean free paths and the different annihilation lengths of dislocations in the softened and hardened lath-packets. The relatively good ductility is shown to be produced by the composite microstructure induced by plastic strain. |
| first_indexed | 2024-03-10T20:01:19Z |
| format | Article |
| id | doaj.art-6de0b65fa0204aa89ac672778453cae9 |
| institution | Directory Open Access Journal |
| issn | 2073-4352 |
| language | English |
| last_indexed | 2024-03-10T20:01:19Z |
| publishDate | 2020-05-01 |
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| series | Crystals |
| spelling | doaj.art-6de0b65fa0204aa89ac672778453cae92023-11-19T23:34:19ZengMDPI AGCrystals2073-43522020-05-0110537310.3390/cryst10050373Deformation Induced Soft and Hard Lath Packets Enhance Ductility in Martensitic SteelsÉva Ódor0Bertalan Jóni1Gábor Ribárik2Nguyen Quang Chinh3Tamás Ungár4Péter J. Szabó5Department of Materials Physics, Eötvös Loránd University Budapest, PO Box 32, H-1518 Budapest, HungaryDepartment of Materials Physics, Eötvös Loránd University Budapest, PO Box 32, H-1518 Budapest, HungaryDepartment of Materials Physics, Eötvös Loránd University Budapest, PO Box 32, H-1518 Budapest, HungaryDepartment of Materials Physics, Eötvös Loránd University Budapest, PO Box 32, H-1518 Budapest, HungaryDepartment of Materials Physics, Eötvös Loránd University Budapest, PO Box 32, H-1518 Budapest, HungaryDepartment of Materials Science and Engineering, Budapest University of Technology and Economics, PO Box 91, H-1521 Budapest, HungaryMartensitic steels are widely used structural materials with outstanding mechanical properties. Their high strength is provided by the non-diffusional phase transformation of <i>fcc</i> γ into thin lamellar <i>bcc</i> plates during fast cooling. Coherency strains between the <i>fcc</i> and <i>bcc</i> lamellae induce large dislocation densities in the range of 10<sup>16</sup> m<sup>−2</sup>, well above the densities attainable by conventional plastic deformation. Using high resolution X-ray line profile analysis, scanning electron microscopy, and hardness tests we show that during tensile deformation when the active Burgers vectors are within the lath plane the lath-packets work soften. On the contrary, when the active Burgers vectors are oblique to the lath-plane the lath-packets work harden. The softening and hardening processes in the differently oriented lath-packets produce a composite of hard and soft components on the length scale of lath-packet size. The stress–strain response of the alloy is discussed in terms of the different mean free paths and the different annihilation lengths of dislocations in the softened and hardened lath-packets. The relatively good ductility is shown to be produced by the composite microstructure induced by plastic strain.https://www.mdpi.com/2073-4352/10/5/373lath martensitecomposite behaviorcharacteristically asymmetric diffraction profileslong-range internal stressesdislocation densities |
| spellingShingle | Éva Ódor Bertalan Jóni Gábor Ribárik Nguyen Quang Chinh Tamás Ungár Péter J. Szabó Deformation Induced Soft and Hard Lath Packets Enhance Ductility in Martensitic Steels Crystals lath martensite composite behavior characteristically asymmetric diffraction profiles long-range internal stresses dislocation densities |
| title | Deformation Induced Soft and Hard Lath Packets Enhance Ductility in Martensitic Steels |
| title_full | Deformation Induced Soft and Hard Lath Packets Enhance Ductility in Martensitic Steels |
| title_fullStr | Deformation Induced Soft and Hard Lath Packets Enhance Ductility in Martensitic Steels |
| title_full_unstemmed | Deformation Induced Soft and Hard Lath Packets Enhance Ductility in Martensitic Steels |
| title_short | Deformation Induced Soft and Hard Lath Packets Enhance Ductility in Martensitic Steels |
| title_sort | deformation induced soft and hard lath packets enhance ductility in martensitic steels |
| topic | lath martensite composite behavior characteristically asymmetric diffraction profiles long-range internal stresses dislocation densities |
| url | https://www.mdpi.com/2073-4352/10/5/373 |
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