Nature of the dark component in carbonitrided steels

Akhant'ev, V. P.; Ivlev, V. I.; Kurbatov, V. P.

doi:10.1007/bf00703174

Cited by 3 publications

(1 citation statement)

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“…B. [7,13,14], dass es unter bestimmten Bedingungen zu einer Porenbildung im Austenit kommen kann. Als Grund werden zum einen eine Übersättigung des Austenits mit C und N und eine Rekombination des Stickstoffs zu N 2 an Gefügestörstellen genannt.…”

Section: Hochtemperaturphasen (T Hoch > a (C3r3cm) ; Austenit)unclassified

Neue Randschichtgefüge carbonitrierter Bauteile und deren Festigkeitseigenschaften

Steinbacher¹,

Hoffmann²,

Zoch³

et al. 2015

HTM Journal of Heat Treatment and Materials

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Kurzfassung/AbstractToday case hardening of highly stressed gear wheels is state of the art, to meet the specific load demands at flank and tooth root. The heat treatment is including a carburization and quenching step in liquids or in gaseous media. The result of the heat treatment of gear wheels is strongly impacting the strength and the load capacity at flank and foot of the treated gears. The typical requirement for the microstructure in the surface near case is a well balanced mixture of finely dispersed retained austenite and martensite. Hard intermediate phases like cementite or other carbides are objectionable. Carbonitriding is an up to now unusual thermo-chemical treatment for parts made of case hardening steels. In the past it was typically applied to increase hardness or hardenability of low alloy steels of moderate hardenability. To do so, the treatment atmosphere was modified by the addition of fixed ammonia rates at low treatment temperatures. Newly developed automatically controlled carbonitriding processes make it possible to set up defined carbon-and nitrogen-depth profiles leading into a significant altered phase-composition of the case. The paper will give an overview on different phase compositions being achievable via carbonitriding and will give examples of carbonitrided samples made of case hardening steels, showing the influence of the heat treatment process and its atmosphere parameters. Also a perspective on the latest development of heat treatment technology for a designated set up of independently controlled carbon and nitrogen potentials for defined depth profiles will be given regarding the interdependency of both elements with each other and the alloy elements. n

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Section: Hochtemperaturphasen (T Hoch > a (C3r3cm) ; Austenit)unclassified