AusEvol Pro: the program for modeling of steel microstructure and mechanical properties (Program...

AusEvol Pro

Program Instructions

2

AusEvol Pro


This program was developed in the “Physical Metallurgy” laboratory (Institute of Applied

Mathematics and Mechanics) of the St. Petersburg State Polytechnic University.

Version 2.5

© 2014

D.F. Sokolov, S.F. Sokolov, A.A. Vasilyev

e-mail: [email protected] or [email protected]

mailto:[email protected]

mailto:[email protected]

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AusEvol Pro


Table of contents

1. GENERAL PROGRAM CHARACTERISTICS ........................................... 4

2. DESCRIPTION OF THE USER INTERFACE …………. ........................... 5

3. GENERAL RULES FOR PORGRAM OPERATION ….. ............................ 7

Entering initial data ...................................................................................... 7

Modeling results . ............................................................................................ 9

Creating a report on modeling results ...................................................... 12

4. LIMITATIONS ON PROGRAM USE ......................................................... 15

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AusEvol Pro


1. GENERAL PROGRAM CHARACTERISTICS

The AusEvol Pro computer program is meant to be used for modeling the evolution of

austenite microstructure during hot deformation, as well as its transformation during subsequent

cooling, to form a set of practically important structural components. The program makes it

possible to quantitatively describe the changes in microstructure of modern low-alloy steels

(including micro-alloyed) under complex regimes of hot rolling or forging, and to evaluate their

final mechanical properties.

The AusEvol Pro program implements an integral mathematical model of the following

interrelated processes of the structuring of steel:

grain growth;

dynamic recrystallization;

static recrystallization taking into account of the effects of recovery and microalloying

elements carbonitrides precipitation on the dislocations of deformed austenite;

austenite phase transformation under continuous cooling with formation of ferrite, pearlite

bainites of different morphology and martensite.

The mathematical models used for the above-given processes of structuring are

distinguished by a physically reasonable allowance for the influence of all practically important

alloying elements. This characteristic is what makes using the AusEvol Pro program effective for

a large number of grades of steel with a wide range of changes in their chemical composition. A

mathematical model is used to calculate the final mechanical properties of steel (yield stress,

tensile stress, elongation) in which the physically reasonable contributions of all practically

important microstructural constituents are accounted for.

The program can be useful in developing new and optimizing existing hot rolling regimes

of modern low-alloy steels, as well as in evaluating the relevant power parameters of equipment.

When using the AusEvol Pro program, one can quantitatively analyze:

the processes of deformed austenite strengthening and softening;

austenite grain size change;

retained strain variation;

microalloying elements carbonitrides volume density and average size changes;

kinetics of austenite transformation and the final microstructure parameters;

mechanical properties of steels.

The AusEvol Pro program was developed in the С++ programming language and can work

on all modern Microsoft Windows family operating systems.

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AusEvol Pro


2. DESCRIPTION OF THE USER INTERFACE

This section provides a general description of the program's interface, namely the elements

of the main user window.

Several functional fields can be highlighted in the main user window of the program (Fig.

1):

Main menu (1);

Instrument panel (2);

Field for working with source data and the results of calculations (3);

Calculation indicator (4);

Status line (5).

Fig. 1. The main window of the AusEvol Pro program.

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AusEvol Pro


The main menu of the program contains the following points:

Menu point Description

Project → New new project creation

Project → Open... opening a previously-created project

Project → Save

save a current project Project → Save as...

Project → Exit exit from the program

Report → Build Report create a report on the results of the modeling of the current

temperature-deformation regime

Help → Manual program instructions

Help → About... program information

The instrument panel provides quick access to the main management functions of the

program:

Quick access button Description

new project

corresponds to menu point: Project → New

download project

corresponds to menu point: Project → Open...

save project

corresponds to menu point: Project → Save

create report

corresponds to menu point: Report → Build Report

The field for entering source data and displaying the results of calculations is made in a

three-paged panel with the windows “Input Data”, “Results” and “Chart”. The “Input Data”

window is meant for entering all of the necessary source data, while the “Results” window is for

viewing the results of modeling, and the “Chart” window is for seeing the graphic results of

calculations. A more in-depth description of how to work with these windows is given in section

3 of these instructions.

The calculation indicator helps the user to follow the calculation process.

In the status line (Fig. 2) the user gets additional information in the form of hints on what

to do with various elements of the program (menu options, buttons, etc.).

Fig. 2. Example of status line display.

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3. GENERAL RULES FOR PROGRAM

OPERATION

This section of the instructions describes the main rules for working in the program:

entering initial data;

modeling results;

creating a report on modeling results.

ENTERING INITIAL DATA

Before making calculations, it’s necessary to enter all the necessary bench mark data using

the “Input Data” tab, including (Fig. 3):

chemical composition of the steel;

the initial size of the austenite grain;

the temperature-deformation regime.

Fig. 3. “Input Data” window with completed tables.

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The chemical composition of steel is entered in the table “Chemical composition” (Fig. 3)

(the content of alloying elements is given in mass %).

The initial Volumetric size of the austenite grain is entered in the field “Initial Grain

Size” (μm).

The according table is used to enter the temperature-deformation regime (Fig. 3), in which

four columns must be entered:

“Time, s” – for entering base times (s);

“Temp., C” – for entering the according temperatures (°С);

“Strain” – for entering deformation values;

“Strain rate” – for entering the according deformation rates (s-1

).

Adding or deleting lines in the given table is done using the buttons: “Add Point” and

“Delete Point”.

The given temperature change regime can be seen on the graph using the “Apply” button.

Fig. 4а gives an example of a complex hot rolling regime. The content of the table

corresponding to this mode is shown in Fig. 4b. It’s noteworthy that the temperature of the

material changes under linear law in the time intervals between base times entered in the table, in

other words the program makes linear interpolations.

a) b)

Fig. 4. An example of entering baseline data in the table (b) in relation to the temperature and

deformation modes shown in the respective graph (a).

The necessary temperature-deformation regime can be entered using the according text file

as well. The user can find an example of such a file in the root catalogue, where the program was

set up during installation (the following route to the file is used by default: C:\Program

Files\SVS Software 2.4\Demo-Projects\AusEvol Pro\test.txt). The “Load…” button must be used

for entering the temperature-deformation regime from the prepared file (Fig. 3).

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AusEvol Pro


After entering all initial data, calculations are then made by using the “Start” button.

MODELING RESULTS

The calculation results received can be viewed in the “Results” and “Chart” windows.

The “Results” window (Fig. 5 and 6) gives calculation data on the corresponding austenite

transformation modes start temperatures, the temperature of the austenite transformation finish,

final microstructure, microalloying elements carbonitrides parameters (volume fraction and size)

and mechanical properties.

Fig. 5. View of the “Results” program window illustrating the results of calculating the

structural composition of final microstructure.

There’s a two-page panel with the tabs “Composition of final microstructure” and “Size

distribution of particles” in the “Result” window for analyzing final microstructure.

One must enter the “Composition of final microstructure” tab to see the final composition

of microstructure (see Fig. 5). The program makes it possible to model the formation of the main

structural components of steel – ferrite, pearlite, bainites of different morphology (granular and

conventional bainite, acircular ferrite) and martensite.

Analysis of the distribution of carbonitride particles of microalloying elements by their size

is done in the “Size distribution of particles” tab (Fig. 6). The user can choose several types of

particles, the delineation of which is modeled in the program:

“Nb(CN) particles” – niobium carbonitride;

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“V(CN) particles” – vanadium carbonitride;

“TiC particles” – titanium carbide.

The choice of particle type is done in the pop-up list “Select size distribution” (Fig. 6).

Fig. 6. “Results” window opened in the program illustrating the results of calculating the

distribution of carbonitride niobium particles by size (“Size distribution of particles” tab).

Fig. 7. “Chart” window opened.

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The user can make and analyze a whole series of various graphs in the “Chart” window

(Fig. 7). The following parameters can be plotted on the Х and Y axes:

Х axis Y axis

Time or Temperature Temperature

Austenite grain size

Retained strain

Nb(C,N) radius

Nb(C,N) vol. density

Nb(C,N) vol. fraction

V(C,N) radius

V(C,N) vol. density

V(C,N) vol. fraction

TiС radius

TiС vol. fraction

TiС vol. fraction

Nb in solution

V in solution

Ti in solution

C in solution

N in solution

B in solution

Austenite vol. fraction

Ferrite vol. fraction

Pearlite vol. fraction

Bainite vol. fraction

GB vol. fraction

CB vol. fraction

AF vol. fraction

Martensite vol. fraction

Accumulated strain Stress

In order to build graphs, one must choose the type of data to be used on the axes from the

special lists provided, and press the “Build” button. An example is given in Fig. 7, showing

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graphs of the change in austenite grain size and austenite volume depending on the time of the

modeled thermo-deformation treatment.

The results graph has a special context menu with several items which can be accessed by

clicking the right mouse button:

Context menu items Description

Export image file…

saves the graph in one of two accessible formats – jpeg or

bmp

Export data file…

exports data to a text file

Settings…

launches the graph settings window

The graph settings window (Fig. 8) allows the user to change the range of values for the

according axes and to choose the axis

type – linear or logarithmic. Hit the

“Preview” button to see a preview of the

changes made, and hit the “Apply”

button to make the changes take place.

Choosing “Export image file” in

the menu, the user can save graphs in a

standard graphic format (bmp or jpeg).

Furthermore, by choosing “Export data

file…” one can save the calculation

results in a text file from which the data

can be imported into any editor program

for further processing.

CREATING A REPORT ON MODELING RESULTS

The program provides the possibility of creating a report on modeling results of the current

regime of thermo-deformation treatment. The basic form of the report contains the following

data:

chemical composition of the steel;

main parameters of the thermo-deformation treatment;

data on microstructure and mechanical properties.

Fig. 8. Program window for setting the graphical

representation of results.

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The user can also additionally change settings of the report form by using a special

window in the program (Fig. 9). To launch this window, the user can use the Maim menu of the

program, or choose the button on the

Instrument panel. One can additionally

indicate the following in the window for

setting report parameters:

the report name;

the report author;

additional graphic data provided in the

report;

other additional information at the

user's discretion.

Following formation of the report by

pressing the “Report” button, a special

window is launched (see Fig. 10) in which

the user can preview the report and

subsequently print it.

Fig. 9. Program window for setting the report

parameters.

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Fig. 10. Program window for previewing and printing reports.

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4. LIMITATIONS ON PROGRAM USE

The AusEvol Pro program makes it possible the user to make correct calculations of a large

range of parameter changes. That said, there are natural limits to these ranges, which must be

kept in mind when working with the program. Calculations should be made only for the

following intervals of parameter changes:

for temperature: T < 1500°С;

for degree of deformation: 0 < ε < 1;

for rate of deformation: 0.01 < dε/dt < 200 c-1

;

for the size of the initial austenite grain: 10 < Dγ0 < 1000 μm.

There are also limitations on the chemical composition of steel. The allowable ranges of

concentrations of alloying elements are shown in Table. 1.

Table 1. Allowable ranges of changes in the concentration of alloying elements, mass. %.

С Mn Si Cu Ni Mo Cr Al Nb V Ti N B S P

Мin 0.001 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Мах 0.7 5 2 2 5 2 5 0.1 0.2 0.2 0.2 0.1 0.01 0.1 0.1

Upon entering values which are outside the specified range, a window appears with a

description of the error type, as well as recommendations on how to correct the error. An

example of such a warning message is given in Fig. 11. The window that appears in this case

informs the user that he or she has incorrectly entered the source data, namely that the user has

incorrectly filled in the settings for the chemical composition of steel.

Fig. 11. Program window for showing errors and recommendations.

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