Abstract
Sub-zero treatment of steels with an Mf below 0°C relies (partly) on a continuation of the martensite formation. The present work reports on the observation of isothermal martensite formation in the sub-zero temperature regime for two steels: AISI 1070 and AISI 52100. Samples were austenitized, quenched in oil, and thereafter investigated with vibrating sample magnetometry, which allows a quantitative assessment of the fraction of retained austenite as a function of the sub-zero temperature and time. Isothermal martensite formation was observed on interrupting the continuous cooling (5 K/min) at temperatures in the range of 80-233 K. The kinetics of isothermal martensite formation depends strongly on the temperature and can be described by Johnson-Mehl-Avrami-Kolmogorov kinetics. Isothermal experiments with dilatometry indicated the occurrence of a volume increase on isothermal holding, consistent with a continuation of the martensitic transformation. On prolonged isothermal holding, a volume reduction was observed for AISI 52100, but not for AISI 1070. Copyright © 2011 by ASTM International.
Original language | English |
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Title of host publication | 18th International Federation for Heat Treatment and Surface Engineering Congress : Proceedings |
Number of pages | 13 |
Publisher | ASTM |
Publication date | 2012 |
Chapter | STP153220120004 |
ISBN (Print) | 9780803175181 |
DOIs | |
Publication status | Published - 2012 |
Event | 18th International Federation for Heat Treatment and Surface Engineering Congress - Rio de Janeiro, Brazil Duration: 28 Jul 2010 → 30 Jul 2010 Conference number: 18 |
Conference
Conference | 18th International Federation for Heat Treatment and Surface Engineering Congress |
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Number | 18 |
Country/Territory | Brazil |
City | Rio de Janeiro |
Period | 28/07/2010 → 30/07/2010 |
Series | ASTM Special Technical Publication |
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Number | 1532 |
Keywords
- Dilatometers
- Isotherms
- Magnetometers
- Martensite
- Martensitic transformations
- Surfaces
- Martensitic steel