Nucleation and growth kinetics of inclusions during liquid steel deoxidation

Abstract

The phenomenon of solid inclusion nucleation and V m molar volume, m3 molÕ 1 growth during the liquid steel deoxidation process is studied numerically. It is shown that the diffusion a i number of pseudomolecules which dissociate of atoms, the Ostwald ripening effect, and per unit time from unit area of particle of class Brownian movement together control the growth of i, mÕ 2 sÕ 1 small size particles. It appears that this stage of b 1i rate constant of growth reaction initial precipitation lasts for only about 10 s. When (i)+ (1) ! (i+ 1), m3 sÕ 1 the particle diameter exceeds a threshold of d i,j collision rate constant, m3 sÕ 1 ~1 mm, the growth process becomes dominated by e turbulent energy dissipation rate, m2 sÕ 3 particle collisions and agglomeration. The efficiency m dynamic viscosity of liquid, Pa s of these mechanisms depends on the particle size n kinematic viscosity of liquid, m2 sÕ 1 distribution as produced during growth. P supersaturation of parent phase or Comprehensive evaluations are still impeded by the dimensionless concentration of limited capacity of computers at present. I&S/1774 pseudomolecules r L density of liquid, kg mÕ 3 At the time the work was carried out the authors were r p density of particles, kg mÕ 3

Inclusion Population Evolution in Ti-alloyed Al-killed Steel during Secondary Steelmaking Process

“…(8). It should be noted that the derived exponent is very close to the value of -3.3 predicted from numerical simulation studies 7,8) where f(r) is the population density function of Al2O3 inclu- ) recalculated by integration of the inclusion PDF in Fig. 10 per size bin.…”

“…A lognormal shape PDF appears whenever evidences indicated the occurrence of active nucleation (deoxidation or reoxidation) in the present study, which is supported by the modeling of nucleation and growth kinetics. 7,8,[18][19][20] This situation is characterized by net mass transfer between solute and inclusion. Inclusion PDF show a power-law distribution that is linear on the logarithm PDF plots when there is no deoxidation or reoxidation event for a while in the secondary steelmaking, which is expected for the processes where particle breakup/coalescence control the size distribution (e.g.…”

“…However, as discussed by Van Ende et al, 6) the Population Density Functions (PDF) provides a practical and user-independent form of the summary of the inclusion size distribution. From theoretical numerical calculations 7,8) of inclusion PDF's, it is known that an inclusion size distribution can change with time, from a lognormal shape distribution at the early stage after nucleation, to a power-law shape distribution at a later mature state after growth, agglomeration and separation. Thus, inclusion size distribution data (PDF) can provide insights on the inclusion formation event/timing and on the inclusion formation mechanism.…”

Nucleation, Growth, Transport, and Entrapment of Inclusions During Steel Casting

“…4, 74 nucleation occurs at nanoscales in both time and length and is governed by diffusion of the deoxidization elements and oxygen, 71,72,75,76 Brownian collision, 27,72,75,76 and Ostwald ripening. 72,[75][76][77][78][79] Particle growth occurs at microscales depending on the microscale phenomena of bubble attachment, turbulent collisions, 27,72,75,76 interface reactions, reoxidation, and local thermodynamics.…”

“…4, 74 nucleation occurs at nanoscales in both time and length and is governed by diffusion of the deoxidization elements and oxygen, 71,72,75,76 Brownian collision, 27,72,75,76 and Ostwald ripening. 72,[75][76][77][78][79] Particle growth occurs at microscales depending on the microscale phenomena of bubble attachment, turbulent collisions, 27,72,75,76 interface reactions, reoxidation, and local thermodynamics. 20,[80][81][82][83] Finally, inclusion transport and removal at the slag or by bubble flotation 24,26,84,85 and particle entrapment in solidifying dendritic interfaces [3][4][5]73 depend on flow transport and on the nature of the flow pattern and shape of the metallurgical vessel.…”