LEARN HOW TO CONTINUOUSLY CAST STEEL ON THE INTERNET AT STEELUNIVERSITY.ORG

LEARN HOW TO CONTINUOUSLY CAST STEEL ON THE INTERNET AT
STEELUNIVERSITY.ORG
D.J. Naylor1, C. Bernhard2, A.M. Green and T. Sjökvist3
1. INTRODUCTION
There is a global concern within the steel industry about the decline in the number of students taking metallurgy
and material science degrees and of graduates who are seeking employment in the industry. Without an influx of
young, talented and highly motivated engineers and scientists, the steel industry will find it difficult to retain its
ability to innovate and remain competitive. Furthermore, those graduates that do join the industry often do not have
sufficient ferrous metallurgy knowledge to become quickly effective in the operation or development of steelmaking
processes or their applications. Consequently steel companies around the world are spending increasing amounts
of time and money providing training programmes for their new recruits. Whilst some of these may be tailored to
the companies’ specific requirements, much of the basic knowledge is common to the whole industry. Another
consequence of this decline is that the number of academics and universities with specialist knowledge of ferrous
metallurgy and with up to date experience of the modern steel industry is also in decline and could soon reach
terminal levels. Without action now, the teaching and researching of ferrous metallurgy in many universities will, in
the medium term, become unsustainable. It is therefore vitally important that the steel industry presents an
improved image of itself to the academic community and to potential recruits, who also need to be better informed
of and more interested in steel and convinced that a career in the industry is stimulating, challenging and
rewarding.
The International Iron and Steel Institute (IISI) has the vision to address this complex problem through the
development of a freely-available, comprehensive package of interactive e-learning resources on steel processing
technologies, products and applications. Targeted at undergraduate students and their professors and in-company
engineers in the steel industry, http://www.steeluniversity.org will help to fill the gap in the knowledge of ferrous
metallurgy.
steeluniversity.org also plays an important role in offering extensive educational resources, which will assist,
support and help to develop academic expertise on steel technologies. This web-based solution also opens up new
opportunities for wider collaboration between universities and with industry at an international level, irrespective of
location and class size.
steeluniversity.org provides the student/trainee with practical examples from the steel industry that illustrate and
apply fundamental scientific, metallurgical and engineering principles. It will also provide a realistic series of linked
simulations of steel processing from raw materials to semi-finished steel products and their applications, in which
the learner takes control of a virtual steel plant and makes operational decisions and experiences the
consequences of these decisions. Other exercises involve the selection of appropriate steels for different
applications and markets. Virtual on-line testing of steel properties is also envisaged. steeluniversity.org also
provides an appreciation of the environmental impacts that steel creates and its contribution to sustainability,
together with and introduction to life cycle assessment techniques. In order to make the contents of this ambitious
e-learning resource attractive to students is the mix of a game and industrial simulation and scientific depth and the
potential for competitions between teams and individuals.
The quality of this website was confirmed when steeluniversity.org was selected as a recipient of one of the
prestigious European Academic Software Awards, 2004. The jurors commended the website for its "Innovative and
Excellent Graphical Simulations, Open-Ended Problems and Integrated Educational Approach".
1
International Iron and Steel Institute, Belgium
Montanuniversität Leoben, Austria
3
University of Liverpool, UK
2
The steeluniversity.org website already has a detailed simulation of secondary steelmaking and currently under
development are simulations of the electric arc furnace and continuous casting. The latter will be of particular
interest to this conference.
2. SIMULATION OF THE ELECTRIC ARC FURNACE
At the beginning of this simulation, the student selects the grade of steel they intend to make and then selects the
type of scrap they want to use and identifies a charging policy for the scrap basket(s) and other alloy or slag
forming additions. To assist in this step a stochiometric sum of all the materials selected is presented to the
student, without any allowance for chemical reactions. The student may assign yields to each element and hence
calculate the amount of oxides that may be formed and the corresponding slag forming additions that may be
necessary. The raw materials then have to be distributed between the scrap baskets, taking account of the density
differences between the various alloys selected. Again, provided the melting process has not commenced the
student may add or remove materials until they are satisfied with their decisions and selections.
They then have to define an activity plan for their EAF process operation, involving the selection of several trigger
and action events. These act as a signal for changing a parameter controlling the operation, e.g. time for the next
basket to be charged, set points for turning power on or off, time to take a sample, the timing of deoxidation and
other alloy and ferro-alloy additions and the time to inject oxygen or carbon. The student may change their activity
plan at any stage, in the light of experience and other events. Some alarm warnings are available to the learner,
e.g. cooling water temperature.
The final action is always tapping. When the required conditions have been satisfied, the steel may be tapped from
the furnace and the simulation is completed. If desired the student can then progress to the secondary steelmaking
operations. As in the secondary simulation, the flexibility of the system allows the learner to define an infinite
number of process routes and charging combinations. The objective is to meet the final requirements of steel
composition, mass, temperature and time at minimum cost. An overview of the simulation is shown in Fig.1.
EAF simulator
User
Start
Stored data
Activity
Plan
Preparation
Furnace
Operation
Evaluation
Preparation:
The user may prepare raw material
additions and design the first process
operations schedule - the activity plan.
The user mainly feeds information to the
system, with some feedback presented in
return to assist in the preparation work.
Furnace Operation:
The user monitor the furnace operation
according to the activity plan. Necessary
corrections, based on sample analysis
and other experiences, are made
throughout the furnace processing.
Evaluation:
The system presents an evaluation of the
process operation to the user :
- Technical objectives fulfilled?
- Economical performance?
The user may also view data for further
understanding of the furnace operations.
End
Fig. 1 Overview of the Electric Arc Furnace Simulation at steeluniversity.org
The student running this simulation will experience something close to running a real modern electric arc furnace.
This means that he/she will be relatively "blind" up to the first sampling and temperature measurement, even
though model calculations are running continuously in the background to simulate the state of the steel in the
furnace. A graphical user interface will be available to student to show how full the furnace is, the position and
condition of the electrodes, the location of the roof, the volume of metal and slag, the temperature and composition
of the steel (when requested).
When the furnace has been tapped the student receives detailed feedback on how they have performed, in terms
of the all the activities performed and the changes to mass, temperature and composition during the operation and
comparing the tap time and temperature, mass and cast composition with the targets and a summary of the
processing costs incurred, broken down into raw materials, energy and time.
Two levels of operation will be available that will be suitable for students and steel works technical personnel
respectively. The former will be offered a basic functionality to enable them to understand and control the process
principals, without too many operational complications, whilst the latter will also have to take into account and cope
with practical disturbances that they had not planned for. These will include short electrodes, electrode breakage,
water panel overheating, and furnace over-filling.
The operating model takes account of the solid, liquid metal, slag and gas phases present in the EAF during its
operation, in terms of their type, mass, composition and density. Several interface models deal with their
interactions and transfers between the phases. The model calculation principle is iterative and prior to each time
step all the material and energy from the previous step are combined with the contributions from external events,
e.g. electrical heating, additions and heat losses and a new calculation is performed including thermal and mass
balances and chemical and thermodynamic modeling, including desulphurisation, dephosphorisation and red-ox
reactions. Various sub-models are also used that take account of the oxygen activity, heat content of the furnace,
liquidus temperature, energy input and heat losses through water cooled panels, radiation, foaming slag.
In this way the simulation should present the learner with a realistic, stimulating and challenging scenario that will
enable them to apply important scientific principles to an industrial process, within an economic framework. It
should also provide them with detailed operational understanding of the electric arc furnace and vividly illustrate
how the EAF is a primary recycling tool, converting scrap steel into new prime product.
The steel produced in this simulation can then be further processed in the virtual secondary steelmaking plant.
This module will be available later in 2005.
3. SIMULATION OF SECONDARY STEELMAKING
The on-line simulation of a secondary steelmaking shop incorporates an argon-stirring station, ladle furnace, an RH
degasser, a tank degasser and a CAS-OB unit, Fig 2. The learner has to make one of several steel grades (a
construction steel, an ultra-low carbon automotive steel, a low sulphur linepipe steel and a low alloy engineering
steel) and is presented with a ladle of steel from the BOS or the EAF (using the output from the module described
above if desired). From here they must decide what additions to make (when and where), which equipment to use
and in what sequence, in order to get the ladle to the right caster within specification, at the required time, at the
right temperature and at minimum cost. They also have to learn how to manipulate the cranes and ladle cars
efficiently and also how to cope with unexpected interruptions and complications.
Supplementary learning packages are also available within this demonstration module which cover deoxidation,
desulphurisation, decarburisation and dehydrogenation, steel cleanness and the importance of slag composition.
A detailed user manual, to assist with the calculations of the required additions is also available on-line.
Feedback is given at the end of the exercise on how successful the student has been in meeting their objectives, in
terms of the composition produced, the time and temperature at casting, the inclusion content and the costs
incurred, Fig 3. The student can also track the changes in chemical composition during their attempt and this can
be used to help them analyse how to do better next time.
Fig 2. The Virtual Secondary Steelmaking Shop at steeluniversity.org
Fig. 3 Feedback to the learner at the end of the Secondary Steelmaking Simulation
The end-point of this simulation is the delivery of the ladle of liquid to steel to a slab, bloom or billet caster,
depending on the grade being produced. It will be possible for the student to further process their steel through the
continuous casting machine.
4. SIMULATION OF CONTINUOUS CASTING
The on-line simulation of the continuous casting process can be run as a stand-alone exercise or can take ladles of
refined steel produced by the learner in the secondary steelmaking simulation described above. One of three
casting machines to produce bloom, slab or billet is available depending on the steel grade being produced and the
application
The user will be able to study what happens in the tundish, in the mold and during the strand formation and cooling
and be able to explore metal flow behaviour in the tundish and into the mold, inclusion removal, the role of tundish
slag and mold flux powders, the effects of superheat, secondary cooling rates, mold stirring and casting speed,
temperature changes, the formation of the meniscus, solidification, soft reduction, the origins of surface and
internal strains, the formation of surface and internal cracking, causes and consequences of break-outs,
segregation, steel cleanness and product geometry.
In operating the virtual continuous casting machine at steeluniversity.org the learner has many critical decisions to
take. These include: •
•
•
•
•
•
•
•
•
•
•
•
•
Which grade of steel to make?
Which product form - bloom, slab or billet?
Ordering of ladles for sequence casting
Operation of the ladle turret to change ladles
Control of metal flow rates from the ladle to the tundish and from the tundish into the mold, through the use
of slide gates and stopper rods
Selection of mold powder
Casting speed
Mold oscillation
Use of EMS
Secondary cooling rate
Use of soft reduction
Control of roll alignment
Cutting the cast product to the required lengths
Several complex models, Figs. 4 and 5, are running in the background of this simulation to ensure that the learner
experiences a realistic impression of the continuous casting process. During the simulation the learner receives
information on the temperature of the steel, flow rate selected, the levels of steel in the ladle, tundish and mold, the
time left for them to empty at the current flow rate, and an indication of the surface and internal quality, inclusion
content and extent of segregation, with a quantification of the number and length of cut strand and the costs they
have incurred.
In 2006 it is planned that a simulation of the hot rolling mill will be available at steeluniversity.org to enable to
student to further process the virtual steel that they have made and cast into a product.
140
Casting speed vc
Shell thickness, mm
120
1.0 m /m in
2.0 m /m in
100
80
60
40
20
Secondary cooling rate:
0.4 l/kg
0.8 l/kg
0
0
5
10
15
20
25
30
35
40
Distance from meniscus, m
Strain, %
Fig. 4 Model to predict the shell thickness of an Ultra Low Carbon steel slab for different casting conditions
2,4
2,2
2
1,8
1,6
1,4
1,2
1
0,8
0,6
0,4
0,2
0
Zone I
Zone II
Zone III
Zone IV
Critical strain
Accumulated strain
Total strain
0
10
20
30
Roll number
40
50
60
Fig. 5 Model to predict total strain (bulging + bending/straightening + misalignment) and accumulated strain of an
Ultra Low Carbon steel slab
5. OTHER E-LEARNING RESOURCES AND FEATURES AT STEELUNIVERSITY.ORG
The website already also contains two modules devoted to the use of steel in two major market applications –
construction and automotive sectors. In the former the diversity of steel types in construction are illustrated and the
student has to identify the key requirements, properties and composition of some of these. The important design
formulae are used and the student has to distinguish between elastic and plastic behaviour and between modulus
and strength. The attributes of different structural materials are then studied. Some of the fabrication techniques
used in structural steelwork are illustrated and the student has to select appropriate corrosion protection methods
and finally the learner identifies the importance of steel to sustainable developments in construction. In the other
steel applications module the student plays to role of a materials engineer in a multi-disciplinary project team, with
the objective of selecting a material (a high strength steel) to reduce the weight of a car door by 25%, again at
minimum cost. They have to address design issues and also the consequences of a higher strength steel on
fabrication and manufacturing techniques such as forming and joining, as well as selecting the most appropriate
corrosion protection method.
A module that will be released in 2005 will deal with the mechanical properties of steel in which the learner will be
introduced to steel standards and specifications for a variety of steel products and applications. An exercise is then
undertaken in which the student has to take samples from a steel plate and undertake virtual tensile, Charpy
impact and hardness tests, within time and budget constraints. A subsequent module will deal with strengthening
mechanisms and alloy design in steels.
Another module to be released in 2005 will address sustainability, steel and the environment. The learner will first
examine the complex social, economic and environmental issues associated with sustainable development and the
important role that steel plays in sustainable development. The IISI sustainability indicators are then introduced to
the learner. The complexity of the environmental impacts caused by mankind and its activities are studied and then
the principles of life cycle thinking are explored, with particular reference to the car as a product. The user then
studies the procedures for undertaking life cycle assessments, with examples of their applications drawn from the
automotive, construction and steel industries. The aim is to give them the confidence and inspiration to use these
techniques and philosophies in their decision-making concerning jobs and life styles.
Over the next three years, it is intended to add new resources to steelunversity.org with simulations of the Blast
Furnace, BOF, continuous casting, hot and cold rolling and modules on the design and selection of engineering
steels, steels for power generation, steels for packaging, environmental management in the steel industry, phase
transformations and heat treatment, recrystallisation and grain growth, coke, sinter, refractories, coatings, corrosion
protection and stainless steels.
It is also planned to introduce an on-line database of expertise involved with the teaching and researching on steel
technologies in academia and steel companies and research institutes, in order to facilitate knowledge and
technology transfer and cooperation between steel industry and academia.
6. CONCLUSIONS
steeluniversity.org is an ambitious, freely-available, initiative being undertaken by the IISI with the help of experts
around the world on steel technologies and the MATTER team at the University of Liverpool who are performing
the coding of these e-learning resources. It provides highly interactive simulations of the major steelmaking
processes and exercises on the selection of steels for important applications, together with an understanding and
implementation of the underlying scientific, engineering and metallurgical principles. These resources are aimed at
raising awareness and interest in students and their teachers about steel and providing valuable, low cost training
and continuing professional development resources for employees in the steel industry supply chain. The
simulations, either singly or in combination, can used as a basis for competitions between individuals or teams.
New simulations on the continuous casting process and the electric arc furnace
http://www.steeluniversity.org.
will be released shortly on
7. ACKNOWLEDGEMENTS
The authors would like to thank the International Iron and Steel Institute and its members for the support to develop
this ambitious website. Particular thanks are also expressed to Mr. A Karangabo, Mr. R. Pierer, Mr. B. Linzer, Mr.
M. Lechner, Mr. S. Michelic of the Institut für Eisenhüttenkunde, Montanuniversität Leoben, Dr C. Chimani, VAI,
Linz and Dr. M Forsthuber, Voest Alpine Donawitz for their significant contributions to the development of this
continuous casting simulation.