I have no measured figures for those dislocation densities as you mentioned. But I can definitely argue that dislocation density strongly depends on the cooling paths traced down by the sample consecutively in the temperature-time-transformation (TTT) diagrams. These diagrams strongly depend on the alloying elements (weakly on the austenitizing temperature, the initial grain size and its distribution, and finally the residual stresses ‘history etc.’).

Case 1) The ferrite-pearlite transformation, which occurs decomposition of the austenite, which contains carbon (i.e., Fe- 0.15wt% C) less then the eutectoid composition (about 0.8wt%C). By slow cooling of the austenite sample from the  austenitizing temperature (range: A3-A1) down to upper pearlite formation temperature range (A1 –pearlite nose T), the pre-eutectoid ferrite precipitates at the austenite grain boundaries and surfaces of inclusions. Subsequent Isothermal annealing below the eutectic temperature A1(723oC)  and well above the TTT nose temperature results formation of very fine pearlite colonies by the nucleation of either cementite or ferrite on an austenite GB. The growth of colony takes place by the edgewise movements of incoherent interface. This process follows by cooling in the air, which results the final microstructure, which is mixture of preeutectic ferrite – pearlite (may be some spheroidized carbide). The Dislocation density depends upon the rate and amount of thermal stresses developed during final quenching cycle, and their relief by micro plastic deformation mechanisms during that period. Depending on the quenching media (water, oil, salt and air etc.) dislocation density may be around 10*8-7 #/cm2 for upper and lower ferrite -pearlite, respectively.

2) Ferrite+bainite+acicular ferrite? The first preeutectic ferrite forms by relatively slow cooling of austenite from the austenitizing region down to bainite isothermal temperature TTT annealing range, and then keeping there for a limited time, the desired amount of bainite formation may be accomplished. The subsequent water quenching below Md temperature the martensite (supersaturated bct ferrite) formation out of retained austenite takes place by shear (diffusionless transformation) mechanisms with a speed of should. This is a duplex structure, where the acicular ferrite phase exist as a thin lenticular shape crystallites form in the interior of the retained austenitic grains. I think very high density of dislocations in the range of 10**10 #/cm2 forms at the interface region to relief the highly localized misfit strain, at room temperature. This closely resembles fine spaced ferrite laths with cementite precipitates during formation of upper bainite, which grows as Widmanstatten side –plate displacement mode.

measure it.

Abhisek, the density of dislocations values are very sensitive to the thermal and mechanical history,  i think you could measure it for your materials. you needs define the technique for the estimation of these values, and the preparation technique because during the preparation also can be modified the dislocations state.

Here is a discussion on techniques for measuring dislocation densities that should be useful:

https://www.researchgate.net/post/How_can_I_calculate_the_dislocation_densities_of_metal_alloys_using_X-ray_diffraction_technique

The determination of dislocation densities in severely deformed copper (cold worked by rolling and/or filings) by NMR technique using quadruple line broadening was described in our Ph.D. thesis at Stanford 1964. This work was also published in METU Journal of Pure and Applied Sciences, Vol.1, No.2 (1968) pp 155-173. Where we found that dislocation densities are 1.8 x 10*11 cm-2 and 7.5 x 10*11 cm-2 deformed samples and filings, respectively.

Where we employed our theoretical work   on the formulation of the  electric field gradient associated with conduction electron redistribution (Friedel type long range oscillations) around dislocations from the first principle. Those findings was applied to  the analysis of Faulkner’s (1959) and Bloembergen and Rowland's (1953) experimental measurements of the derivative maximum Gmax and the integrated intensity I versus Gmax ratios obtained  for the various deformations. Unfortunately, this work was forgotten  in shelves of METU's and Harvard' s  libraries !!!  But it was extensively used by O. Kanert (2006) in his highly regarded work in Germany

Thank you for your comments