Bainite

About: Bainite is a research topic. Over the lifetime, 9520 publications have been published within this topic receiving 145305 citations.

Mechanical Properties of Low-Temperature Bainite

Abstract: The mechanical properties of a bainitic microstructure with slender ferrite plates (20-65 nm in thickness) in a matrix of carbon-enriched retained austenite were characterized. The microstructure is generated by isothermal transformation at temperatures in the range 200-300°C. A yield strength as high as 1.5 GPa and an ultimate tensile strength between 1.77 to 2.2 GPa was achieved, depending on the transformation temperature. Furthermore, the high strength is frequently accompanied by ductility (£ 30%) and respectable levels of fracture toughness (

Kinetics of the bainite transformation

Abstract: A theory is developed for the evolution of bainite as a function of time, temperature, chemical composition and austenite grain size. The model takes into account the details of the mechanism of transformation, including the fact that nucleation begins at the austenite grain surfaces, and that the growth of a sheaf occurs by the repeated nucleation of small platelets. Predictions made using the model are shown to compare well against published isothermal and continuous cooling transformation data.

High-strength steel plate and manufacturing method thereof

Abstract: Disclosed is a high-strength steel plate having superior ductility and stretch flangeability and a tensile strength (TS) of 980 MPa or higher, and having 0.17-0.73% C, 3.0% or less Si, 0.5-3.0 or less Mn, 0.1% or less P, 0.07% S, 3.0% or less Al, 0.010% or less N, and 0.7% or more Si + Al, an area ratio of martensite of 10-90% with respect to the entire steel plate composition, a residual austenite amount of 5-50%, and an area ratio of bainitic ferrite in the upper bainite of 5% or less with respect to the entire steel plate composition. Twenty-five percent or more of the aforementioned martensite is tempered martensite, and the total of the area ratio of the aforementioned martensite with respect to the entire steel plate composition, the aforementioned residual austenite amount and the area ratio of the aforementioned bainitic ferrite in the upper bainite with respect to the entire steel plate composition is 65% or more. The area ratio of polygonal ferrite with respect to the entire steel plate composition is 10% or less (including 0%), and the average amount of C in the aforementioned residual austenite is 0.70% or more.

Variant Selection of Reversed Austenite in Lath Martensite

Abstract: The microstructure of partially reversed lath martensite in 13%Cr–6%Ni steel was examined by electron backscatter diffraction, and the crystallographic character of the reversed austenite is discussed in relation to the mechanism of ‘austenite memory’. Most of the reversed austenite grains had the same orientation as the original austenite matrix before martensitic transformation. However, some austenite grains had a different orientation in a twin relationship to the other major austenite grains, although all the reversed austenite grains retained a Kurdjumov–Sachs relationship to the martensite matrix. On the basis of the crystallographic relationships among the habit plane, the close packed direction of austenite and the martensite lath boundary, we suggest that the austenite variants are theoretically limited to two kinds within one packet and five kinds within one original austenite grain. In addition, we found that internal stress introduced by martensitic transformation plays an important role in determining the austenite variant: internal stress operates so that reversed austenite selects the same variant as that present in the original austenite matrix before martensitic transformation. This phenomenon is understood as the austenite memory.