TY - JOUR
T1 - Formation mechanism of bainitic ferrite in an Fe-2 Pct Si-0.6 Pct C alloy
AU - Tsuzaki, Kaneaki
AU - Kodai, Aki
AU - Maki, Tactashi
PY - 1994/9/1
Y1 - 1994/9/1
N2 - The bainite transformation at 723 K in an Fe-2 pct Si-0.6 pct C alloy (mass pct) was investigated with transmission electron microscopy (TEM) and quantitative metallography to clarify the growth mechanism of the ferritic component of bainite. In early stages of transformation, the bainitic ferrite was carbide free. The laths of bainitic ferrite within a packet were parallel to one another and separated by carbon-enriched retained austenite. The average carbon concentration of the bainitic ferrite was estimated to be 0.19 mass pct at the lowest, indicating that the ferrite was highly supersaturated with respect to carbon. The laths did not thicken during the subsequent isothermal holding, although they were in contact with austenite of which the average carbon concentration was lower than the paraequilibrium value. In the later stage of transformation, large carbide plates formed in the austenite between the laths, resulting in the decrease in the carbon concentration of the austenite. Subsequently, the ferrite with a variant different from the initially formed ferrite in the packet was decomposed for the completion of transformation. The present results indicate that the bainitic ferrite develops by a displacive mechanism rather than a diffusional mechanism.
AB - The bainite transformation at 723 K in an Fe-2 pct Si-0.6 pct C alloy (mass pct) was investigated with transmission electron microscopy (TEM) and quantitative metallography to clarify the growth mechanism of the ferritic component of bainite. In early stages of transformation, the bainitic ferrite was carbide free. The laths of bainitic ferrite within a packet were parallel to one another and separated by carbon-enriched retained austenite. The average carbon concentration of the bainitic ferrite was estimated to be 0.19 mass pct at the lowest, indicating that the ferrite was highly supersaturated with respect to carbon. The laths did not thicken during the subsequent isothermal holding, although they were in contact with austenite of which the average carbon concentration was lower than the paraequilibrium value. In the later stage of transformation, large carbide plates formed in the austenite between the laths, resulting in the decrease in the carbon concentration of the austenite. Subsequently, the ferrite with a variant different from the initially formed ferrite in the packet was decomposed for the completion of transformation. The present results indicate that the bainitic ferrite develops by a displacive mechanism rather than a diffusional mechanism.
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U2 - 10.1007/BF02649049
DO - 10.1007/BF02649049
M3 - Article
AN - SCOPUS:0028495606
VL - 25
SP - 2009
EP - 2016
JO - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
JF - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
SN - 1073-5623
IS - 9
ER -