Numerical modeling of diffusion-controlled phase transformations in ternary systems and application to the ferrite/austenite transformation in the Fe-Cr-Ni system

Isothermal and continuous cooling transformation (CT) diagrams help users map out diffusion-controlled phase transformations of austenite to various mixtures of ferrite and cementite. This chapter discusses the application as well as limitations of these engineering tools in the context of heat treating eutectoid, hypoeutectoid, and proeutectoid steels. It also provides references to large collections of transformation diagrams and includes several diagrams that plot quenching and hardening transformations as a function of bar diameter.

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Kinetic Monte Carlo Method to Model Diffusion Controlled Phase Transformations in the Solid State

Handbook of Materials Modeling ◽

10.1007/1-4020-3286-2_115 ◽

2005 ◽

pp. 2223-2248 ◽

Cited By ~ 2

Author(s):

Georges Martin ◽

Frédéric Soisson

Keyword(s):

Monte Carlo ◽

Solid State ◽

Monte Carlo Method ◽

Phase Transformations ◽

Kinetic Monte Carlo ◽

Kinetic Monte Carlo Method ◽

Diffusion Controlled ◽

Model Diffusion

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Effects of Austenitization Temperature and Pre-Deformation on CCT Diagrams of 23MnNiCrMo5-3 Steel

Materials ◽

10.3390/ma13225116 ◽

2020 ◽

Vol 13 (22) ◽

pp. 5116

Author(s):

Ivo Schindler ◽

Rostislav Kawulok ◽

Petr Opěla ◽

Petr Kawulok ◽

Stanislav Rusz ◽

...

Keyword(s):

Phase Transformations ◽

Deformation Temperature ◽

True Strain ◽

Austenitization Temperature ◽

Diffusion Controlled ◽

Significant Acceleration ◽

Wide Range ◽

Mean Grain Size ◽

Cct Diagrams ◽

Kinetics Of

The combined effect of deformation temperature and strain value on the continuous cooling transformation (CCT) diagram of low-alloy steel with 0.23% C, 1.17% Mn, 0.79% Ni, 0.44% Cr, and 0.22% Mo was studied. The deformation temperature (identical to the austenitization temperature) was in the range suitable for the wire rolling mill. The applied compressive deformation corresponded to the true strain values in an unusually wide range. Based on the dilatometric tests and metallographic analyses, a total of five different CCT diagrams were constructed. Pre-deformation corresponding to the true strain of 0.35 or even 1.0 had no clear effect on the austenite decomposition kinetics at the austenitization temperature of 880 °C. During the long-lasting cooling, recrystallization and probably coarsening of the new austenitic grains occurred, which almost eliminated the influence of pre-deformation on the temperatures of the diffusion-controlled phase transformations. Decreasing the deformation temperature to 830 °C led to the significant acceleration of the austenite → ferrite and austenite → pearlite transformations due to the applied strain of 1.0 only in the region of the cooling rate between 3 and 35 °C·s−1. The kinetics of the bainitic or martensitic transformation remained practically unaffected by the pre-deformation. The acceleration of the diffusion-controlled phase transformations resulted from the formation of an austenitic microstructure with a mean grain size of about 4 µm. As the analysis of the stress–strain curves showed, the grain refinement was carried out by dynamic and metadynamic recrystallization. At low cooling rates, the effect of plastic deformation on the kinetics of phase transformations was indistinct.

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A New Diffusivity Database for Multi-Component Al Alloys: Focusing on Ternary Systems and its Effect on Microstructure Evolution during Solidification

Materials Science Forum ◽

10.4028/www.scientific.net/msf.794-796.611 ◽

2014 ◽

Vol 794-796 ◽

pp. 611-616 ◽

Cited By ~ 8

Author(s):

Li Jun Zhang ◽

Dan Dan Liu ◽

Wei Bin Zhang ◽

Shao Qing Wang ◽

Ying Tang ◽

...

Keyword(s):

Microstructure Evolution ◽

Hybrid Approach ◽

Ternary Systems ◽

Atomic Mobility ◽

First Principles Calculations ◽

Liquid Phases ◽

Diffusion Controlled ◽

Mobility Database ◽

Diffusion Paths ◽

Diffusion Properties

A new atomic mobility database for Fcc_A1, L12, Bcc_A2, Bcc_B2, and liquid phases in the Al-Cu-Fe-Mg-Mn-Ni-Si-Zn system has been established via a hybrid approach of experiment, first-principles calculations and DICTRA (DIffusion Controlled TRAnsformation) software, focusing on the atomic mobility parameters in ternary systems. Various diffusivities can be computed as a function of temperature and composition. The reliability of this diffusivity database is further validated by comparing the calculated and measured diffusion properties in a series of ternary and quaternary diffusion couples, including concentration profiles, diffusion paths, interdiffusion fluxes, and so on. The effect of the diffusivity database on microstructure evolution during solidification is demonstrated by the phase field simulation of primary (Al) grains in Al356.1 alloy. The simulation results indicate that such accurate diffusivity database is highly needed for the quantitative simulation of microstructural evolution during solidification.

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