Interphase boundary precipitation of VC accompanying ferrite and pearlite transformation in medium carbon steels

Goro Miyamoto, Poorganji Behrang, Tadashi Furuhara

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)

Abstract

Demands for medium carbon steels with high strength used for forging parts in automobile have been increasing. V addition to such steels leads to interphase boundary precipitation (IBP) of VC and thus an increase of strength. However, mechanism and strengthening effect of IBP have not been clarified in detail. In this study, precipitation of VC accompanying ferrite and pearlite transformations and its effect on hardness have been examined in medium carbon steels microalloyed with 0.3%V. Specimens transformed in a temperature range between 873 and 973K consist of pearlite and small amount of proeutectoid ferrite. Hardness increase by the V addition becomes larger by lowering transformation temperature at these temperatures. Meanwhile the alloying effect of V on the hardness remarkably decreases at 823K where bainite transformation takes place partly. TEM characterization has revealed that VC are precipitated in both of proeutectoid and pearlitic ferrites in the manner of fine rows parallel to the austenite / ferrite interphase boundary. The size of VC decreases and its number density increases by lowering transformation temperature, corresponding to the larger hardness increase. Orientation relationship analyses between ferrite and austenite in the V-added specimen based of EBSD measurements reveals that proeutectoid ferrite grows preferentially towards an austenite grain with which ferrite does not hold a specific orientation relationship, indicating that classical ledge mechanism does not play a role for interphase boundary precipitation of VC in this alloy.

Original languageEnglish
Title of host publicationSolid-Solid Phase Transformations in Inorganic Materials
PublisherTrans Tech Publications Ltd
Pages420-425
Number of pages6
ISBN (Print)9783037851432
DOIs
Publication statusPublished - 2011

Publication series

NameSolid State Phenomena
Volume172-174
ISSN (Print)1012-0394

Keywords

  • EBSD
  • Ferrite transformation
  • Interphase boundary precipitation
  • Orientation relationship
  • Precipitation strengthening

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Materials Science(all)
  • Condensed Matter Physics

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