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An Atom Probe Study of Κ-Carbide Precipitation in Austenitic Lightweight Steel and the Effect of Phosphorus
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
  • Laura Bartlett, Missouri University of Science and Technology
  • David C. Van Aken, Missouri University of Science and Technology
  • Julia E. Medvedeva, Missouri University of Science and Technology
  • D. Isheim
  • N. Medvedeva
  • K. Song
Abstract

The influence of phosphorus on κ-carbide precipitation and alloy partitioning in an austenitic Fe-30Mn-9Al-1Si-0.9C-0.5Mo cast steel was studied utilizing a combination of transmission electron microscopy, 3D atom probe tomography, X-ray diffraction, and first-principles atomistic modeling. Increasing the amount of phosphorus from 0.006 to 0.043 wt pct P increased the kinetics of the initial ordering reaction. Specimens from the high-phosphorus steel showed some degree of short-range ordering of Fe-Al-C that took place during the quench. It was shown that phosphorus increases both the size and volume fraction of κ-carbide during aging. However, the distribution of phosphorus appears to be homogeneous, and thus long-range diffusion of phosphorus was not responsible for the observed increase in hardening. It is shown that phosphorus encourages the initial short-range ordering into the E21 structure of κ-carbide and also accelerates spinodal decomposition associated with carbon and aluminum diffusions.

Department(s)
Materials Science and Engineering
Second Department
Physics
Comments
This study was supported in part by the Army Research Laboratory under contracts from Battelle Memorial Institute (contract W911NF-07-D-0001) and Benet Laboratories (contract W15QKN-07-2-0004), and by the National Science Foundation€™s MRSEC program (DMR-0520513) and made use of its Shared Facilities at the Materials Research Center of Northwestern University. Laura Bartlett was also supported by a U.S. Department of Education GAANN fellowship under contract P200A0900048. The FEI Tecnai F20 scanning/transmission electron microscope was obtained through a Major Research Instrumentation grant from the NSF under contract DMR-0922851.
Keywords and Phrases
  • Alloy steel,
  • Aluminum,
  • Austenite,
  • Carbides,
  • Carbon,
  • High resolution transmission electron microscopy,
  • Manganese,
  • Molybdenum,
  • Precipitation (chemical),
  • Probes,
  • Reaction kinetics,
  • Spinodal decomposition,
  • Transmission electron microscopy,
  • X ray diffraction, 3d atom probe tomographies,
  • Atomistic modeling,
  • Carbide precipitation,
  • First principles,
  • Light-weight steels,
  • Long-range diffusion,
  • Order reactions,
  • Short range ordering, Phosphorus
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2017 The Minerals, Metals & Materials Society and ASM International, All rights reserved.
Publication Date
11-1-2017
Disciplines
Citation Information
Laura Bartlett, David C. Van Aken, Julia E. Medvedeva, D. Isheim, et al.. "An Atom Probe Study of Κ-Carbide Precipitation in Austenitic Lightweight Steel and the Effect of Phosphorus" Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science Vol. 48 Iss. 11 (2017) p. 5500 - 5515 ISSN: 1073-5623; 1543-1940
Available at: http://works.bepress.com/laura-bartlett/17/