A debate on the bainite reaction

An investigation of the mechanism of bainite transformation in experimental 0.2c-1v-2mn steel

“…The T 0 temperature can be defined [6,9,12] such that stress free austenite and ferrite of the same composition (with respect to both the interstitial and the substitutional alloying elements) are in metastable equilibrium. Thus any displacive transformation involving a full supersaturation of carbon (i.e.…”

“…bainitic ferrite would then inherit the carbon content of the parent austenite) can occur only below the appropriate T 0 temperature. The T 0 ' curve allows for 400J/mol of stored energy in the bainitic ferrite to take account of the strain energy due to the invariant-plane strain shape change that accompanies the growth of bainitic ferrite [6,12,13].…”

Some Aspects of Bainite Transformation in Fe-Based Alloys

“…The kinetic definition for the bainite transformation in steels has been discussed as one of three principle definitions [1,2]. This definition is based on the fact that the bainite transformation has its own C-curve between the pearlite or proeutectoid ferrite and the martensite ranges on a TlT diagram, and becomes incomplete as the decomposition temperature approaches to the upper limiting temperature of this curve (the kinetic-Bs).…”

“…It is however well known that the C-curves of bainite and pearlite overlap extensively in plain carbon steels and the kinetic-Bs appears usually in particular steels containing an appreciable proportion of strong carbide formers such as Mo and Cr. Aaronson and his co-workers [1, 2,5] thus claim that the kinetic-Bs appears to be the result of the solute drag-like effect [ll] of the strong carbide formers on the proeutectoid ferrite reaction, and that the appearance of the kinetic-Bs does not mean a different transformation mechanism for the bainite reaction. It has been proposed that the substitutional elements may segregate to the transformation interfaces and then reduce the activity of carbon in austenite resulting in the low growth rate of proeutectoid ferrite [ll].…”

Bainite Formation in High Carbon Copper Bearing Steels

“…Under this generalised microstructural definition of bainite, bainite is the product of the diffusional nucleation and the competitive diffusional growth of the two phases comprising the products of a eutectoid reaction [7]. In steels a local equilibrium is established at the austenitetfemte interface [15] and the carbides precipitate at the interface [16]. One of the models derived from this theory is the ledge mechanism [17].…”