The microstructure of lath martensite in quenched 9Ni steel.
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| Title: | The microstructure of lath martensite in quenched 9Ni steel. |
|---|---|
| Authors: | Kinney, C.C.1, Pytlewski, K.R.1, Khachaturyan, A.G.1, Morris, J.W.1 jwmorris@berkeley.edu |
| Source: | Acta Materialia. May2014, Vol. 69, p372-385. 14p. |
| Subjects: | Microstructure, Martensite, Metal quenching, Nickel steel, Backscattering, Electron diffraction, Phase transitions |
| Abstract: | Abstract: Many of the most useful structural steels have dislocated lath martensitic structures. The microstructures of these steels are complex since each prior austenite grain contains as many as 24 different crystallographic variants of the γ(fcc)–α′(bcc) transformation. Recent research, using electron backscatter diffraction (EBSD), has significantly clarified the “block-and-packet” structure of lath martensite in low-carbon steel. The blocks are bivariant composites of two transformation variants, with the three distinct blocks stacked so that all six of the possible variants of the packet are used. The present work was undertaken to complete the description of this structure and identify its underlying causes. We address these issues in two steps. First, we present an EBSD characterization of lath martensite in low-carbon 9Ni steel. The results show that all packets have the bivariant block structure, and, with the proper notation, the full hierarchical structure has a simple pattern that is easily described and visualized. The results are readily explained on the basis of two assumptions: (i) the bivariant block, in contrast to a single-variant block, has an α′–γ invariant plane very near {011}α″||{111}γ, which permits the plate-shaped blocks to stack without significant strain to form a packet; (ii) the transformation goes to completion, with the consequence that the net strain in the prior austenite grain is a simple dilatation, and polygranular bodies can transform martensitically without significant residual stress. In a companion paper we use an appropriate modification of the crystallographic theory of lath martensite to validate the first of these assumptions. [Copyright &y& Elsevier] |
| Copyright of Acta Materialia is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: The microstructure of lath martensite in quenched 9Ni steel. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Kinney%2C+C%2EC%2E%22">Kinney, C.C.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Pytlewski%2C+K%2ER%2E%22">Pytlewski, K.R.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Khachaturyan%2C+A%2EG%2E%22">Khachaturyan, A.G.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Morris%2C+J%2EW%2E%22">Morris, J.W.</searchLink><relatesTo>1</relatesTo><i> jwmorris@berkeley.edu</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Acta+Materialia%22">Acta Materialia</searchLink>. May2014, Vol. 69, p372-385. 14p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Microstructure%22">Microstructure</searchLink><br /><searchLink fieldCode="DE" term="%22Martensite%22">Martensite</searchLink><br /><searchLink fieldCode="DE" term="%22Metal+quenching%22">Metal quenching</searchLink><br /><searchLink fieldCode="DE" term="%22Nickel+steel%22">Nickel steel</searchLink><br /><searchLink fieldCode="DE" term="%22Backscattering%22">Backscattering</searchLink><br /><searchLink fieldCode="DE" term="%22Electron+diffraction%22">Electron diffraction</searchLink><br /><searchLink fieldCode="DE" term="%22Phase+transitions%22">Phase transitions</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Abstract: Many of the most useful structural steels have dislocated lath martensitic structures. The microstructures of these steels are complex since each prior austenite grain contains as many as 24 different crystallographic variants of the γ(fcc)–α′(bcc) transformation. Recent research, using electron backscatter diffraction (EBSD), has significantly clarified the “block-and-packet” structure of lath martensite in low-carbon steel. The blocks are bivariant composites of two transformation variants, with the three distinct blocks stacked so that all six of the possible variants of the packet are used. The present work was undertaken to complete the description of this structure and identify its underlying causes. We address these issues in two steps. First, we present an EBSD characterization of lath martensite in low-carbon 9Ni steel. The results show that all packets have the bivariant block structure, and, with the proper notation, the full hierarchical structure has a simple pattern that is easily described and visualized. The results are readily explained on the basis of two assumptions: (i) the bivariant block, in contrast to a single-variant block, has an α′–γ invariant plane very near {011}α″||{111}γ, which permits the plate-shaped blocks to stack without significant strain to form a packet; (ii) the transformation goes to completion, with the consequence that the net strain in the prior austenite grain is a simple dilatation, and polygranular bodies can transform martensitically without significant residual stress. In a companion paper we use an appropriate modification of the crystallographic theory of lath martensite to validate the first of these assumptions. [Copyright &y& Elsevier] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Acta Materialia is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1016/j.actamat.2014.01.058 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 14 StartPage: 372 Subjects: – SubjectFull: Microstructure Type: general – SubjectFull: Martensite Type: general – SubjectFull: Metal quenching Type: general – SubjectFull: Nickel steel Type: general – SubjectFull: Backscattering Type: general – SubjectFull: Electron diffraction Type: general – SubjectFull: Phase transitions Type: general Titles: – TitleFull: The microstructure of lath martensite in quenched 9Ni steel. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Kinney, C.C. – PersonEntity: Name: NameFull: Pytlewski, K.R. – PersonEntity: Name: NameFull: Khachaturyan, A.G. – PersonEntity: Name: NameFull: Morris, J.W. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 05 Text: May2014 Type: published Y: 2014 Identifiers: – Type: issn-print Value: 13596454 Numbering: – Type: volume Value: 69 Titles: – TitleFull: Acta Materialia Type: main |
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