3D Cellular Automata Modelling of Solid–state Transformations Relevant in Low–alloy Steel Production

2011 ◽  
Vol 172-174 ◽  
pp. 1140-1145 ◽  
Author(s):  
Maria Giuseppina Mecozzi ◽  
C. Bos ◽  
Jilt Sietsma
Keyword(s):  
Cellular Automata ◽  
Three Dimensional ◽  
Steel Production ◽  
Structural Defects ◽  
Low Alloy Steels ◽  
Transformation Kinetics ◽  
Austenite Transformation ◽  
Ferrite Transformation ◽  
Alloy Steels ◽  
Microstructural Modelling

A three-dimensional cellular automata (CA) model is developed for the kinetic and microstructural modelling of the relevant metallurgical mechanisms occurring in the annealing stage of low–alloy steels: recrystallisation, pearlite–to–austenite transformation and ferrite–to–austenite transformation on heating and austenite–to–ferrite transformation on cooling. In this model the austenite–to–ferrite transformation is described by a mixed–mode approach, which implies that the transformation kinetics is controlled by both the interface mobility and the diffusivity of the partitioning elements. This approach also allows incorporation of the ferrite nucleation occurring on structural defects. The developed CA algorithm, in which the transformation rules for the grain boundary and interface cells are controlled by the growth kinetics of the forming phase, allows three-dimensional systems to be treated within relatively short simulation times. The simulated microstructure reproduces quite well the microstructure observed in experimental samples. A good agreement is obtained between the experimental and simulated ferrite recrystallisation and ferrite and austenite transformation kinetics. The present approach also models the development of the carbon concentration profile in the austenite, which is, for instance, essential for subsequent martensite formation.

Microstructure Modelling of Solid-State Transformations in Low-Alloy Steel Production

2012 ◽  
Vol 706-709 ◽  
pp. 2782-2787 ◽  
Author(s):  
Maria Giuseppina Mecozzi ◽  
C. Bos ◽  
J. Sietsma
Keyword(s):  
Dual Phase Steel ◽  
Three Dimensional ◽  
Steel Production ◽  
Transformation Kinetics ◽  
Band Formation ◽  
Cellular Automata Model ◽  
Cold Rolled ◽  
Microstructural Band ◽  
Mn Concentration ◽  
Metallurgical Processes

In this work the formation of microstructural banding in a dual-phase steel is investigated by using a three-dimensional cellular automata model for phase transformations. Originally developed for describing the metallurgical processes occurring during the annealing stage of cold-rolled strips, this model is presently applied to investigate microstructural-band formation during the austenite-to-ferrite transformation kinetics during cooling after hot rolling. The recent incorporation in the model of an inhomogeneous concentration of Mn, the alloying element most responsible for the development of microstructural banding, and the local nucleation behaviour dependent on the Mn concentration allows the study of the effect of material and process parameters on the banding formation.

Evaluation of Empirical Kinetics Models of Athermal Martensite Transformation in Plain Carbon and Low Alloy Steels

2013 ◽  
Vol 798-799 ◽  
pp. 39-44 ◽  
Author(s):  
Seok Jae Lee
Keyword(s):  
Exponential Function ◽  
Martensite Transformation ◽  
Low Alloy Steels ◽  
Transformation Kinetics ◽  
Kinetics Models ◽  
Alloy Steels

In this paper, the empirical kinetics models for athermal martensite transformation in plain carbon and low alloy steels were reviewed. Four models based on an exponential function were selected and evaluated by comparing with the published values of M50 and M90 temperatures. It was confirmed that the model proposed by Lee and Van Tyne resulted in more accurate predictions of athermal martensite transformation kinetics by considering the composition dependent parameters and the exponent term to express a sigmoidal shaped curve.

Growth of Individual Austenite Grains Measured with 3DXRD Microscopy

2007 ◽  
Vol 561-565 ◽  
pp. 2301-2304 ◽  
Author(s):  
V.I. Savran ◽  
S. Eric Offerman ◽  
Niels H. van Dijk ◽  
Erik M. Lauridsen ◽  
L. Margulies ◽  
...  
Keyword(s):  
Three Dimensional ◽  
European Synchrotron Radiation Facility ◽  
Growth Behavior ◽  
Continuous Heating ◽  
Austenite Formation ◽  
Low Alloy Steels ◽  
Alloy Steels ◽  
Austenite Grains ◽  
Individual Grains

Studying austenitisation in steel, so far, was either limited to observations at the surface of the material or to the determination of the average grain growth behavior in the bulk. The development of the three-dimensional X-ray diffraction (3DXRD) microscope at beam line ID11 of the European Synchrotron Radiation Facility in Grenoble, France, made it possible to study the transformation kinetics in-situ and at the level of individual grains in the bulk of the material. Unique in-situ observations of austenite growth kinetics during continuous heating experiments were made for two commercial low-alloy steels (C22 and C35). The observed growth behavior of individual austenite grains gives a valuable contribution to understanding the phase transformations on heating, i.e. austenite formation from ferrite and pearlite.

In Situ Neutron Diffraction during Thermo-Mechanically Controlled Process in Low Alloy Steels

2006 ◽  
Vol 118 ◽  
pp. 419-424
Author(s):  
M.S. Koo ◽  
Ping Guang Xu ◽  
J.H. Li ◽  
Yo Tomota ◽  
O. Muransky ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Volume Fraction ◽  
Structural Evolution ◽  
Low Alloy Steels ◽  
Controlled Processing ◽  
Ferrite Transformation ◽  
Alloy Steels ◽  
Time Division ◽  
In Situ Neutron Diffraction

A challenge was made to examine the micro-structural evolution during thermomechanically controlled processing (TMCP) by in situ neutron diffraction. Since the neutron beam is too weak to achieve a time-division measurement to follow a rapid transformation in alow carbon steel, 2%Mn was added to make the austenite to ferrite transformation slower. Round bar specimens were heated up to 900°C with an electrical resistance method, then cooled down to 700°C, and compressed by 25% followed by step-by-step cooling. During the step-by-step cooling, neutron diffraction profiles were obtained and the volume fraction of ferrite, phase stresses and FWHM were analyzed. Using a similar TMCP simulator, specimens were quenched into water at several stages of the heat schedule to freeze the corresponding microstructures, which were observed with OM and SEM. As results, the ferrite volume fraction determined by neutron diffraction on cooling agrees well with that by microscopy. It is found that the austenite deformation and/or Nb addition accelerate the ferrite transformation to result in finer grain size.

Localization of Partial Magnetization around Artificial Slits in Square Bars of Medium Carbon Low Alloy Steel JIS S45C

2011 ◽  
Vol 217-218 ◽  
pp. 1297-1302 ◽  
Author(s):  
M. Uryu ◽  
Katsuyuki Kida ◽  
Takashi Honda ◽  
Edson Costa Santos ◽  
K. Saruwatari
Keyword(s):  
Stress Concentration ◽  
Three Dimensional ◽  
Hall Probe ◽  
Low Alloy Steels ◽  
Film Sensor ◽  
Medium Carbon ◽  
Alloy Steels ◽  
Probe Microscope ◽  
Non Destructive

Fatigue failure of steel occurs when cracks form and grow in the material’s stress concentration area. In order to understand the relation between stress concentration and crack propagation phenomena, non-destructive evaluation methods that can be related to in-situ measurements around the stress concentration area are necessary. In the present work, we developed a scanning Hall probe microscope (SHPM) equipped in a GaAs film sensor and observed three dimensional magnetic fields at room temperature in air. Medium carbon low alloy steels specimens (JIS, S45C) were used in the experiments. Only the area around the artificial slit had been magnetized and the effect of the magnetization area on the artificial slit was observed.

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