Visualization of austenite formation during heating in alloy steels

Eric Schmidt, Sridhar Seetharaman

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


Experiments utilizing a hot-stage confocal scanning laser microscope (CSLM) have been carried out to observe phase transformations in two steels, 4118 and 4320. Austenite formation during continuous heating and isothermal conditions were investigated on the surface of samples that were etched to reveal the ferrite and eutectoid regions. It was found that the austenite precipitated at eutectoid/ferrite boundaries. Austenite would then proceed to cover the eutectoid regions first and thereafter a distinguishable γ/α front would proceed advance through the ferrite. Anywhere from 2 to 5 fronts could be observed in each ferrite grain, but did not originate preferentially based on surrounding microstructure. In most cases, only 1 austenite front was observed to advance through a eutectoid colony. The rates of front advancement occurred at higher temperatures and were slightly faster in 4118 than 4320 when subjected to non-isothermal growth conditions. Non-isothermal growth rates were generally non-linear. Front advancement rates under isothermal conditions were generally linear, were significantly faster in 4320 than 4118, and displayed a first order relationship to superheat (T - Tα→γ).

Original languageEnglish (US)
Title of host publicationMaterials Science and Technology 2005 - Proceedings of the Conference
Number of pages13
StatePublished - 2005
Externally publishedYes
EventMaterials Science and Technology 2005 Conference - Pittsburgh, PA, United States
Duration: Sep 25 2005Sep 28 2005

Publication series

NameMaterials Science and Technology
ISSN (Print)1546-2498


OtherMaterials Science and Technology 2005 Conference
Country/TerritoryUnited States
CityPittsburgh, PA


  • Austenite formation
  • CSLM
  • Phase transformations
  • Steel

ASJC Scopus subject areas

  • Engineering(all)


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