Metallography of bainitic transformation in silicon containing steels

Journal Article · Tue Nov 01 04:00:00 EST 1977 · Metall. Trans., A; (United States)

DOI:https://doi.org/10.1007/BF02646868· OSTI ID:6378380

Huang, D H ^[1]; Thomas, G

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1. Rohm and Haas Co. Research Laboratories, Bristol, PA

The formation of carbide in lower bainite was studied in two silicon containing carbon steels by transmission electron microscopy and diffraction techniques. Epsilon carbide was identified in the low temperature isothermally transformed bainite structure. The crystallographic relationship between epsilon carbide and bainitic ferrite was found to follow the Jack orientation relationship, viz, (0001) epsilon parallel (011)..cap alpha.., (10 anti 1 1) epsilon parallel (101)..cap alpha... The cementite observed in the lower bainite was in the shape of small platelets and obeyed the Isaichev orientation relationship with the bainitic ferrite, viz, (010)c parallel (1 anti 1 1)..cap alpha.., (103)c parallel (011)..cap alpha... Direct evidence showing the sequence of carbide formation from austenite in bainite has also been obtained. Based on the observations and all the crystallographical features, it is strongly suggested that in silicon containing steels the bainitic carbide precipitated directly from austenite instead of from ferrite at the austenite/ferrite interface as has been proposed by Kinsman and Aaronson. The uniformity of the carbide distribution is thus envisaged to be the outcome of precipitation at the austenite--ferrite interphase boundary.

• OSTI ID: 6378380
• Journal Information: Metall. Trans., A; (United States), Journal Name: Metall. Trans., A; (United States) Vol. 8:11; ISSN MTTAB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
AUSTENITE
BAINITE
CARBIDES
CARBON ADDITIONS
CARBON COMPOUNDS
CARBON STEELS
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
ELECTRON MICROSCOPY
IRON ALLOYS
IRON BASE ALLOYS
MARTENSITE
METALLOGRAPHY
MICROSCOPY
PHASE TRANSFORMATIONS
SILICON ALLOYS
STEELS
TWINNING