Modelling of {gamma}/{alpha} transformation in niobium-containing microalloyed steels

Journal Article · Fri Mar 05 04:00:00 EST 1999 · Scripta Materialia

DOI:https://doi.org/10.1016/S1359-6462(99)00025-1· OSTI ID:347543

Lee, K J; Lee, J K ^[1]

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1. Pohang Iron and Steel Co., Ltd. (Korea, Republic of). Technical Research Labs.

In Nb-containing steels where Nb is a strong carbide former throughout rolling and cooling, {gamma}/{alpha} transformation is usually retarded. However, the formation of Nb precipitates formed during rolling retards recrystallization of austenite, which would subsequently result in an acceleration of {gamma}/{alpha} transformation due to reduction in the amount of solute Nb as well as in the austenite grain size. In Fe-C-M systems, where M is a substitutional alloying element, there is a transition from the M-controlled slow-reaction regime with low-supersaturation to the carbon-controlled fast-reaction regime with high-supersaturation. If M is a strong carbide forming element such as Nb, V, Ti, and Mo, interface precipitation occurs at a proper migration rate of a {gamma}/{alpha} grain boundary, whereas matrix precipitation in ferrite is prevailed when the growth rate is fast. In the present study, the transformation modes for ferrite, pearlite, bainite, and interface NbC precipitation were derived based on the experimental and the theoretical approaches.

• OSTI ID: 347543
• Journal Information: Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 7 Vol. 40; ISSN 1359-6462; ISSN SCMAF7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BAINITE
CARBIDES
CRYSTAL-PHASE TRANSFORMATIONS
FERRITE
MATHEMATICAL MODELS
NIOBIUM ADDITIONS
PEARLITE
PRECIPITATION
STEELS
THERMODYNAMICS