The sub-zero Celsius treatment of precipitation hardenable semi-austenitic stainless steel

Matteo Villa, Mikkel Fougt Hansen, Marcel A. J. Somers

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Abstract

A precipitation hardenable semi-austenitic stainless steel AISI 632 grade was austenitized according to industrial specifications and thereafter subjected to isothermal treatment at sub-zero Celsius temperatures. During treatment, austenite transformed to martensite. The isothermal austenite-to-martensite transformation was monitored in situ by magnetometry and data was used to sketch a TTT diagram for transformation. As an alternative treatment, after austenitization the material was immersed in boiling nitrogen and up-quenched to room temperature by immersion in water prior to be subjected to isothermal treatment. Magnetometry showed that the additional thermal step in boiling nitrogen yields a minor increment of the fraction of martensite, but has a noteworthy accelerating effect on the transformation kinetics, which more pronounced when the isothermal holding is performed at a higher temperature. Data is interpreted in terms of instantaneous nucleation of martensite during cooling followed by time dependent growth during isothermal holding.
Original languageEnglish
Title of host publicationHeat Treating 2015: Proceedings of the 28th ASM Heat Treating Society Conference
Number of pages5
PublisherASM International
Publication date2015
Pages431-435
ISBN (Electronic)978-1-62708-105-4
Publication statusPublished - 2015
Event28th ASM Heat Treating Society Conference - Detroit. MI, United States
Duration: 20 Oct 201522 Oct 2015
Conference number: 28

Conference

Conference28th ASM Heat Treating Society Conference
Number28
CountryUnited States
CityDetroit. MI
Period20/10/201522/10/2015

Cite this

Villa, M., Hansen, M. F., & Somers, M. A. J. (2015). The sub-zero Celsius treatment of precipitation hardenable semi-austenitic stainless steel. In Heat Treating 2015: Proceedings of the 28th ASM Heat Treating Society Conference (pp. 431-435). ASM International.