Austenite decomposition during continuous cooling of an HSLA-80 plate steel
- Colorado School of Mines, Golden, CO (United States)
Decomposition of fine-grained austenite (10-{micro}m grain size) during continuous cooling of an HSLA-80 plate steel (containing 0.05C, 0.50Mn, 1.12Cu, 0.88Ni, 0.71Cr, and 0.20Mo) was evaluated by dilatometric measurements, light microscopy, scanning electron microscopy, transmission electron microscopy, and microhardness testing. Between 750 C and 600 C, austenite transforms primarily to polygonal ferrite over a wide range of cooling rates, and Widmanstaetten ferrite sideplates frequently evolve from these crystals. Carbon-enriched islands of austenite transform to a complex mixture of granular ferrite, acicular ferrite, and martensite (all with some degree of retained austenite) at cooling rates greater than approximately 5 C/s. Granular and acicular ferrite form at temperatures slightly below those at which polygonal and Widmanstaetten ferrite form. At cooling rates less than approximately 5 C/s, regions of carbon-enriched austenite transform to a complex mixture of upper bainite, lower bainite, and martensite (plus retained austenite) at temperatures which are over 100 C lower than those at which polygonal and Widmanstaetten ferrite form. Interphase precipitates of copper form only in association with polygonal and Widmanstaetten ferrite. Kinetic and microstructural differences between Widmanstaetten ferrite, acicular ferrite, and bainite (both upper and lower) suggest different origins and/or mechanisms of formation for these morphologically similar austenite transformation products.
- OSTI ID:
- 264075
- Report Number(s):
- CONF-941016--
- Journal Information:
- Metallurgical Transactions, A, Journal Name: Metallurgical Transactions, A Journal Issue: 6 Vol. 27; ISSN 0360-2133; ISSN MTTABN
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BAINITE
CHROMIUM ADDITIONS
COPPER ALLOYS
DILATOMETRY
FERRITE
GRAIN SIZE
IRON BASE ALLOYS
KINETICS
MANGANESE ADDITIONS
MARTENSITE
MICROHARDNESS
MICROSTRUCTURE
MOLYBDENUM ADDITIONS
NICKEL ADDITIONS
OPTICAL MICROSCOPY
PHASE TRANSFORMATIONS
SCANNING ELECTRON MICROSCOPY
TEMPERATURE DEPENDENCE
TRANSMISSION ELECTRON MICROSCOPY
WIDMANSTAETTEN STRUCTURE