Estimation of the effective growth rate of a plate of bainitic ferrite in dynamic theory

Abstract

Abstract-The growth of a bainite plate is considered to be a relay type process, in which fast (with τ g ~ 10 -10 s) acts of the formation of sublaths (with a width 3d ~ 1 μm, where d is the thickness of the sublath) occur in an ultrasonic regime and the successive acts are separated by pauses of length τ p ~ 10 -2 s. The value τ p corre sponds to the time of diffusion on a scale d with allowance for the pipe diffusion. The effective growth rate of the plate of bainite ferrite v eff is estimated by the relationship 3d/τ p .

Fundamental Achievements of the Dynamic Theory of Reconstructive Martensitic Transformations

“…If the condition of diffusion suppression at the spatial scale d is satisfied, the critical rates of austenite cooling required for transition to martensite lamellar morphology of several alloyed steels [33] acquire a natural valuation [34]. On the contrary, characteristic times of incubation under isothermal exposure of austenite (overcooled to temperature B s > M s ), preceding the fast growth of lath crystals of bainitic ferrite, are caused by carbon diffusion within the spatial scale d [35].…”

Possibility of wave control of the formation of twinned austenite in the process of the formation of bainitic ferrite

“…In our previous works [4][5][6][7], the formation of a macroplate of bainitic ferrite has been considered based on the assumption that the lath crystals in the macroplates that arise in the supersonic regime via the martensitic mechanism [8,9]. This means that, in the elastic fields of defects, there are local regions with lowered interphase barriers for the appearance of ini tial excited states (IESs) in the form of extended rect angular parallelepipeds.…”

Possible Wave Processes Controlling the Growth of Martensite Crystals at B2-B19, B2-B19' and B2-R Transformations

“…16. The estimations of scales of incubatory times during the forming of a macroplate of bainitic ferrite [15]. This opens a wide field of activity for using the diverse tools of physical acoustics in the analysis of the morphological features of separate crystals (e.g., of plate-like or wedge-like forms), their junctions (acute and obtuse), mutual intersections, interactions with grain boundaries, etc., on the basis of the concepts of the CWP as a superposition of wave beams propagating in metastable austenite and capable of disturbing its stability.…”