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Article
Nitriding of Lightweight High Manganese and Aluminum Steels
International Journal of Metalcasting
  • Laura Bartlett, Missouri University of Science and Technology
  • Sabra C. Serino
Abstract

Austenitic high manganese and aluminum steels have exceptional combinations of high strength and toughness with excellent wear resistance. Adding aluminum in levels from 6 to 8.8 wt% reduces the density by 10-15 % compared with quenched and tempered Cr and Mo steels but also decreases strain hardening and abrasive wear resistance. Wear resistance may be improved by a low-cost heat treatment in a nitrogen atmosphere to produce a hard layer of surface AlN. In the current study, the effect of aluminum and silicon content on the kinetics of nitriding process was evaluated for a Fe- 30 %Mn-(6-9 %) Al-(1-1.6 %)Si-0.9 %C steel in the temperature range of 900-1100°C (1652-2012°F). Results show that up to a 550-lm-thick surface layer ofAlN plates can be produced, depending on the time and temperature. Increasing the amount of silicon from 1.1 to 1.6 % Si had no statistical effect on the diffusion of nitrogen in the temperature range of 900-1100°C (1652-2012°F). Increasing the amount of aluminum from 6 to 8.8 % Al decreased the diffusivity of nitrogen and increased the calculated activation energy from 64 to 79 kJ/mol. The lower than expected values of the activation energy for the diffusion of nitrogen in austenite is suggested to be the result of the development of high-diffusivity pathways at the interface between the AlN and the austenite matrix.

Department(s)
Materials Science and Engineering
Keywords and Phrases
  • Activation energy,
  • Aluminum,
  • Austenite,
  • Chemical activation,
  • Heat resistance,
  • High strength steel,
  • Manganese,
  • Nitriding,
  • Nitrogen,
  • Strain hardening,
  • Wear resistance,
  • High diffusivities,
  • High manganese steel,
  • High strength and toughness,
  • Nitriding process,
  • Nitrogen atmospheres,
  • Precipitation kinetics,
  • Statistical effects,
  • Surface nitriding,
  • Aluminum nitride
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2016 American Foundry Society, All rights reserved.
Publication Date
4-1-2016
Citation Information
Laura Bartlett and Sabra C. Serino. "Nitriding of Lightweight High Manganese and Aluminum Steels" International Journal of Metalcasting Vol. 10 Iss. 2 (2016) p. 190 - 200 ISSN: 1939-5981
Available at: http://works.bepress.com/laura-bartlett/9/