scholarly journals Study of phase transformations in complex phase steel using a mesoscale cellular automaton model Part I: Modeling Fundamentals

2020 ◽  
Vol 72 (3) ◽  
pp. 17-31
Author(s):  
Jarosław Opara ◽  
Roman Kuziak
Keyword(s):  
Phase Transformations ◽  
Mesoscale Model ◽  
Concentration Field ◽  
Carbon Diffusion ◽  
Study Phase ◽  
Homogeneous Microstructure ◽  
Complex Phase ◽  
Hybrid Cellular Automata ◽  
Microhardness Distribution ◽  
Digital Material

A two-dimensional mesoscale model based on the concept of hybrid cellular automata is developed to study phase transformations in a complex phase steel during continuous cooling. The model is capable of simulating microstructure evolution with carbon diffusion in the volume and along grain boundaries, γ/α interfaces migration into austenite, as well as formation of bainite and martensite islands during intensive cooling in lower temperatures. In contrast to the classic statistical approaches which are based on the assumption of modeling one point in the material with homogeneous microstructure, the proposed phase transformations’ model in the mesoscale accounts for material heterogeneity. The simulation results in the form of a digital material representation with microstructures and maps showing the carbon concentration field as well as microhardness distribution are presented. One of the main advantages of the model is that has only seven adjustment coefficients that are used in the fitting process.

scholarly journals Study of phase transformations in complex phase steel using a mesoscale cellular automaton model Part II: Experiments and Validation

2020 ◽  
Vol 72 (3) ◽  
pp. 32-44
Author(s):  
Jaroslaw Opara ◽  
Roman Kuziak
Keyword(s):  
Phase Transformations ◽  
Mesoscale Model ◽  
Goal Function ◽  
Study Phase ◽  
Complex Phase ◽  
Microhardness Distribution ◽  
Validation Parameters ◽  
Wide Range ◽  
Microstructure Morphology ◽  
Predicted Values

A two-dimensional mesoscale model based on the concept of hybrid cellular automata was used to study phase transformations in a complex phase steel during continuous cooling. This model enables simulation of the decomposition of austenite into ferrite, bainite, and martensite, accompanied by calculations of volume and grain boundary diffusion of carbon. In effect, as a result, one can observe the morphology of simulated microstructures, corresponding carbon segregation as well as microhardness distribution. These results with the kinetics of austenite to ferrite phase transformation and predicted values of the complex phase steel hardness are the subject of model validation. A series of dilatometric experiments were carried out with constant cooling rates in order to construct a CCT diagram and validate the presented model. The convergence of simulated results with empirical outcomes was confirmed quantitatively using a dedicated goal function and data summaries in the table and graphs. However, some qualitative and quantitative discrepancies in terms of microstructure morphology are indicated which was possible thanks to applying a wide range of different validation parameters of the model. It is emphasized how crucial is the use of appropriate validation methodology.

PHASE TRANSFORMATIONS DURING HEATING OF AMORPHOUS/NANOCRYSTALLINE Ni–Ti POWDERS

2010 ◽  
Vol 24 (09) ◽  
pp. 1137-1140 ◽  
Author(s):  
M. M. VERDIAN ◽  
M. SALEHI ◽  
K. RAEISSI
Keyword(s):  
Differential Scanning Calorimetry ◽  
Solid State ◽  
Phase Transformations ◽  
Low Energy ◽  
Heating Process ◽  
Study Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Niti Phase

Amorphous/nanocrystalline 50 Ni –50 Ti powders were synthesized from elemental Ti and Ni powders by solid state synthesis utilizing low energy mechanical alloying with times up to 100 h. The produced powders were investigated by X-ray diffraction and differential scanning calorimetry to study phase transformations that occurred during heating in the calorimeter. It was found that at the first stage of the heating process, a disordered NiTi phase was formed at temperature of about 400°C. Further investigations indicated that this phase transformed into the Ni 3 Ti and Ti 2 Ni intermetallic compounds after heating at a temperature of about 800°C.

scholarly journals Numerical Modeling of Phase Transformations in Dual-Phase Steels Using Level Set and SSRVE Approaches

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5363
Author(s):  
Krzysztof Bzowski ◽  
Łukasz Rauch ◽  
Maciej Pietrzyk ◽  
Marcin Kwiecień ◽  
Krzysztof Muszka
Keyword(s):  
Phase Transformations ◽  
Level Set ◽  
Numerical Solutions ◽  
Computing Time ◽  
Carbon Diffusion ◽  
Computational Domain ◽  
Numerical Tests ◽  
Austenitic Transformation ◽  
Reliable Model ◽  
New Phase

Development of a reliable model of phase transformations in steels presents significant challenges, not only metallurgical but also connected to numerical solutions and implementation. The model proposed in this paper is dedicated to austenitic transformation during heating and ferritic transformation during cooling. The goal was to find a solution which allows for the decreasing of computing time without noticeable decreasing the accuracy and reliability of the model. Proceedings to achieve this goal were twofold. Statistically Similar Representative Volume Element was used as a representation of the microstructure. It allowed for the reducing of the complexity of the computational domain. For the purpose of the model, carbon diffusion was assumed to be the main driving force for both transformations. A coupled finite element–level set method was used to describe growth of a new phase. The model was verified and validated by comparing the results with the experimental data. Numerical tests of the model were performed for the industrial intercritical annealing process.

Phase Transformations and Interstitial Atom Diffusion in Iron-Nitride, Iron-Carbonitride and Iron-Carbide Layers

2006 ◽  
Vol 46 ◽  
pp. 32-41 ◽  
Author(s):  
Andreas Leineweber ◽  
Tatiana Liapina ◽  
Thomas Gressmann ◽  
Marc Nikolussi ◽  
Eric J. Mittemeijer
Keyword(s):  
Solid State ◽  
Phase Transformations ◽  
Interstitial Atom ◽  
Iron Carbide ◽  
Layer Growth ◽  
Iron Nitrides ◽  
Iron Nitride ◽  
Study Phase ◽  
Atom Diffusion ◽  
Kinetics Of

α-Iron foils were exposed to various gas atmospheres containing all or a number of the components NH3, CO, H2 and N2 for different periods of time at 550°C. In this way surficial compound layers were generated which contain different iron nitrides (ε, γ’), iron carbonitride (ε) and/or iron carbide (cementite, Fe3C). These compound layers were used to study phase transformations associated with N- and/or Cdiffusion processes in the corresponding phases. These studies involved (a) the layer-growth kinetics of cementite and (b) various solid-state phase transformations occurring in compound layers upon annealing in vacuum.

A method of heat treating samples to study phase transformations

1966 ◽  
Vol 7 (11) ◽  
pp. 740-740
Author(s):  
M. P Braun ◽  
I. G. Neizhko
Keyword(s):  
Phase Transformations ◽  
Heat Treating ◽  
Study Phase

Phase Transformations and Photocatalytic Activity of TiO2 Powders Preparation via Microwave-Assisted Sol-Gel Method

2013 ◽  
Vol 717 ◽  
pp. 79-83
Author(s):  
Weerachai Sangchay ◽  
Pichet Chantawee ◽  
Weerachai Madtharak
Keyword(s):  
Phase Transformations ◽  
Anatase Phase ◽  
Sol Gel ◽  
Microwave Oven ◽  
Study Phase ◽  
Photocatalytic Efficiency ◽  
Gel Method ◽  
Sol Gel Method ◽  
Microwave Assisted ◽  
Photocatalytic Activities

The purpose of this research was to study phase transformation and photocatalytic properties of TiO2powders. TiO2powders were prepared by microwave-assisted sol-gel method. The prepared powders were refluxed at 18 W to 450 W for 1 h and dried at 180 W for 1 h by a conventional microwave oven. The phase transformations of powders were characterized by XRD and photocatalytic activities of powders were evaluated by UV-Vis spectrophotometer. The results show all samples reveal that only the anatase phase and has the crystallite size is 13.8, 10.3 and 9.2 nm when the refluxed at 180, 300 and 450 W. It was found that TiO2powders refluxed at 450 W were found to give the highest photocatalytic efficiency is about 90.06% under UV irradiation for 6 h.

scholarly journals Metallurgical phase transformations in the rubbing of steels

1988 ◽  
Vol 418 (1855) ◽  
pp. 405-424 ◽  
Keyword(s):  
Phase Transformations ◽  
Carbon Diffusion ◽  
First Time

The theory of the transient frictionally generated temperatures that are necessary to produce hard metallurgically transformed material in the rubbing of steels is re-examined and it is found that these temperatures are much higher than has previously been assumed. Carbon diffusion is shown to be the rate-determining process. The revised theory is confirmed by experiments in which, for the first time, such phase-transformed material is produced as a result of a single rubbing contact.

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