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Implications of carbon, nitrogen and porosity on the γ→α′ martensite phase transformation and resulting hardness in PM-steel Astaloy 85Mo

Damon, James; Dietrich, Stefan; Schulze, Volker

Abstract:
This study aims at a thorough characterization of the relationship of interstitially solved carbon and nitrogen on the γ → α′ transformation in PM steels, the accompanied volume change and the resulting hardness. Furthermore, the investigations include multiple porosity levels of 6.9, 7.2 and 7.35 g/cm$^{3}$ to characterize porosity effects. Dilatometric samples were carburized and carbonitrided to seven distinct compositions to account for common compositions in the process of thermochemical case hardening heat treatment. The dilatometric samples were rapidly austenitized and quenched and the dilatometric response was evaluated. To fully characterize the martensitic transformation of PM steels, X-ray diffractometry evaluated the amount of retained austenite after quenching. Conclusive results of iterative quenching procedures along with elemental analysis after heat treatment give distinct evidence that PM steels underlie rapid decarburization. This effect ultimately leads to an erroneous evaluation of the martensite transformation kinetics, especially the often proposed effect of porosity on M$_{S}$. However, a distinct effect on the accompanied volume change from austenite to martensite is proposed. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000120119
Veröffentlicht am 12.10.2020
Originalveröffentlichung
DOI: 10.1016/j.jmrt.2020.05.035
Dimensions
Zitationen: 3
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Angewandte Materialien - Werkstoffkunde (IAM-WK)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 07.2020
Sprache Englisch
Identifikator ISSN: 2238-7854
KITopen-ID: 1000120119
Erschienen in Journal of materials research and technology
Verlag Elsevier
Band 9
Heft 4
Seiten 8245–8257
Vorab online veröffentlicht am 09.05.2020
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