STS BLOOM CASTER FOR SPECIAL STEELS

STARTED 2010 IN THE OLDEST HIGH-TECH

METALLURGICAL CENTRE OF RUSSIA

CELEBRATING 250th

YEAR OF PRODUCTION OF

TOP LEVEL STEEL QUALITY

Giorgio CABAI president STS Fabrizio CABAI managing director STS Matteo BELLINA technical manager STS

IZHSTAL celebrated its 250 year anniversary in 2010 and STS had the honor to supply &

successfully commission the Continuous Casting Machine tailored to their peculiar melting

shop layout and designed to meet the highest quality demand of blooms, mini-slabs and

billets.

STS is proud to have been an active part of this celebration where quality and pioneering

leading high technology was the philosophy of this company.

In fact IZHSTAL is since so many years the Steel Metallurgical Centre with no stop

research and achievement, even the famous Mr. Nobel was a manager in this plant and

Mr. Putin himself witness the STS caster start-up, confirming the high strategic value of

this plant.

Mr. Putin at plant cast ceremony (source: from Russian TV)

The unique technological processes have been implemented over the years with quality

results that would surprise any visitor of their marvelous private Museum where processes

are so well reproduced.

STS got the order for the CASTER on turn-key basis including initial consumables, with

performance guarantees, based on a thick book of strict standards covering more than 150

steel grades covering of most extreme and wide industrial applications.

IZSHTAL highly qualified and experienced managers and staff has been extremely

cooperative in all phases of the project but at the same time very demanding for their

quality targets exceeding the world standards.

Finally after long and comprehensive testing on a wide range of products fulfilling the

performance guarantees, STS obtained from JSC MANAGEMENT COMPANY MECHEL that

owns this plant, the acceptance certificate and a letter of compliments.

In line with STS conservative philosophy, we have decided to release news on this plant

only after full good plant production and performance and in full agreement with the

owners.

The caster with three strands, is designed to serve the two E.A. Furnaces and LF

respectively with 30t and 42t maximum capacity, to produce sizes of sections ranging from

#100x100mm to #180x180mm and cutting lengths ranging from 4m to 12m.

The main characteristics of the plant equipment supplied can be summarized as follows:

MAIN TECHNICAL FEATURES

Machine Radius 7m

Number of Strands Three (3)

Steel Grades Low, medium and high carbon steels, stainless, medium

and high alloyed

Ladle Capacity Maximum 42t with sliding gate system and porous plugs

Sequencing Facility Ladle car for two ladles with hydraulic lifting system

Weighing Management Tundish and Ladle monitoring by load cells

Tundish type 10t capacity operating with protected or open stream,

controlled by stopper rods or nozzle changers

Tundish Car Fully cantilevered, equipped with hydraulic lifting system

Casting Equipment #125x125mm and #140x180mm

Mould Type Curved, tubular, multi tapered 1.000mm long with

electromagnetic stirrer

Speed Control With minimum radioactive emission and automatic start

Mould Lubrication By alternative proportioning pump with variable flow and

automatic powder delivery system

Mould Oscillator Hydraulically controlled with adjustable stroke and

frequency

Guiding Apron In line electromagnetic stirrers, pneumatically

pressurized guiding rolls with progressive force

according to billet size and casting speed, optical billet

temperature monitoring

Withdrawal Straightener Double radius 7/13m, two withdrawal powered rolls,

computer pneumatic pressure control during casting

according to cast size and speed or re-stranding function

Dummy Bar System Solid type with overhead tilting/parking, pneumatically

controlled

Cutting System By automatic innovative oxygen / gas, cutting torch

suitable also for stainless steel, having high speed

cutting capability with long flame powerful cutting tip for

minimum metal loss and perfect cutting surface creating

minimum scarf

Scarf Removal Automatic blade type system

Cutting length Adjustable from minimum 4m to 12m with very strict

tolerances of few millimetres

Billet Identification Unique STS impact type computer controlled marking

machine installed on transfer roller table with combine b

billet weighing, marking 12 personalized characters each

billet

Billet Transfer Single rollers for all strands

Billet Discharge Overhead bridge picking up each billet, lifting by

approximately 2m and transferring on first notch of

cooling bed, same bridge can feed hot billet transfer or

short billet sorting

Cooling System Hydraulic turnover walking beam cooling bed with

grouping of billets for easy removal and storing by

overhead crane (machine already designed for future

application of billet slow cooling system for special steels

treatment)

Pollution Control The machine is equipped with fume extraction also in the

torch area

Auxiliary Equipment Controlled cooling furnaces designed for a wide range of

qualities

Plant Supervision HMI level 2

Erection of the caster has been executed focusing on the utmost precision and care

required by the strategic and high quality production of this plant.

Record installation time was not a point of discussion on a plant so fully accessorized and

with a so high target of quality and production level.

In fact from the first meetings was clear and agreed that the important point was to have

the best available technologies installed, for a casting plant that must be a reference for

the biggest Russian steel company on his historical and most important production site.

Thus the caster, as can be deducted by the preliminary data reported above, had been

equipped and completed in the better way with accessories for high quality production,

with the most advanced automation and controls for the process on line monitoring, for

precise and sure bloom managing system with bloom weighting, sorting, marking and with

controls and supervision for operators help and for monitoring of machine operation and

status.

We report here below some details on the most advanced and peculiar characteristics of

this machine.

MACHINE DETAILS

In details and specifically for bloom quality the following special cares and equipment

have been applied on the caster to fulfill the requests, just to mention the most important

technical solutions of a caster that was considered for STS as “special” from any point of

view:

1. Mould powder automatically controlled powder addition system The system is independent for each strand and is installed on top part of tundish cars as

per below sketch.

The system is composed by dedicated silos with capacity sufficient for a complete

sequence, the silo is equipped with heating system to assure moisture free powder to be

fed into the mould, with level controls and at silo base a suitable dosing system

pneumatically actuated delivers the right amount of powder according to casting condition

in a completely automatic way.

Suitable duct flushed with Argon convey and distribute the powder on the meniscus.

With this system the operators are only monitoring the situation on the meniscus, being

able with 1 operator to monitor more than 1 strand in more safe and with more consistency

and reliability of the process.

2. Argon feeding controls for tundish to mould area The system is composed by a dedicated Argon box installed on the tundish and equipped

with flow controls to deliver the right amount of purging gas to the connection between

tundish nozzle and submerged shroud.

The system allows fulfilling the requested guaranteed values over gas pick–up in the final

product.

3. Multi taper copper tubes with profiles selected specifically for the condition of the Izhstal plant

The copper tube design was very critical due to the wide variety of steel grades to be cast

and so to the wide range of casting speed values, the best solution has been found with

complex multi taper design in several steps to assure proper contact for all the grades to

be cast, with first priority at most critical ones.

4. Automatic mould level control with fast start-up The STS in house developed control system has been utilized for fast response even with

low power radioactive source; this system allows full control by STS of all working

parameters for a fast set up and immediate performance just after start-up.

The capability of the STS mould level control system was of prime importance in Izhstal

plant mainly for the requests on bloom surface quality that requires an absolutely stable

level in every condition.

The precise and easily adjustable response of the STS controller allow also the Customers

to work even with old radioactive sources that with other systems must be changed earlier

for decay with time spending procedures.

5. Mould electromagnetic stirrer with external coils for the quickest cast size change and better flexibility of the machine and strand stirrer with adjustable position to be moved according to cast size and casting condition in the best possible way to comply with the solidification and metallurgical requirement of ALL the steel grades to be cast and produced in TOP quality

Due to stringent requests of bloom internal quality and segregation a couple of stirrers

have been considered in all strands: the upper one giving the best improvement on

surface and primary solidification structure, and the second one along the curve giving his

contribution to the internal quality soundness and eliminating segregation.

In consideration of the quite different size of the cast product and the wide range of steel

grades the strand stirrer in the apron has been designed to be moved along the radius be

positioned at correct solidification point in any casting condition and precisely for the

segregation-critical steels.

6. Completely automatic cooling water management for both primary and secondary cooling, with dedicated nozzles on secondary cooling cages and bloom continuous temperature monitoring for all strands at cooling chamber exit

The system is adjusted in a completely automatic mode via control valves and suitable

sensors following the specific casting condition and steel grade according to specific

“recipes” inserted in the system.

Additional feedback of bloom temperature measured at the exit of the cooling chamber is

also giving control for double checking that the process is running as per set and

requested metallurgical condition.

7. Cutting torches with powder addition system for stainless steel fast and precise cutting in any condition and with fume suction system

For the blooms cutting the torches were chosen for the absolute need of avoiding the

deformation created by the shears, and the special high alloyed steels to be produced in

Izhstal requires the iron powder addition, so this system has been integrated in STS

designed high speed simple and reliable cutting torches creating a dedicated machines

set, that has been equipped also with fume suction system due to the local stringent rules

also for safety and health in the working environment.

The torches has been tested during performance period on all steel grades cutting with

reliability and safety all products.

8. Bloom de-burring system The absolute care of Izhstal for product quality and the need of eliminating time consuming

procedures of bloom conditioning STS was asked also to install device to clean the little

burr created on the lower face of the blooms by torch cutting.

We’ve done this in line with our common view of the machinery, that need to be simple

sturdy and reliable, and we’ve created a simple “knife device” pneumatically actuated that

hits the blooms under face cleaning it very efficiently.

On the following picture the appearance of 140x180 mm bloom ends as per STS cut and

de-burring process.

9. Bloom slow cooling system The wide variety of steel grades produced, comprising steels for bearings, steels for tools

and for springs had suggested to have in the CCM provision for future installation of bloom

slow cooling system.

This was required from metallurgical point of view to assure quality of the hard steel

grades preventing in these qualities cooling cracks and assuring proper structure for

further processing.

The slow cooling system has been fully engineered from STS with a dedicated couple of

beds totally insulated and covered, designed for 10 and 12 m bloom lengths.

The bloom handling system in the caster has been already made suitable for discharging

the blooms on dedicated roller tables for immediate transfer to the slow cooling beds.

The system installation has then been postponed for organization reasons.

On the other side specifically for bloom control and management the following special

cares and equipment have been applied on the caster to fulfill the requests:

1. Bloom weighting system on transfer roller table The wide variety of steels produced and the need of optimize the length and weights for

production control and further rolling optimization asked for on line weighting of the

blooms.

The weighting system is installed on the transfer roller table and is served by a lifter that

lifts up the bloom from the roller table and sits it on load cells.

the weight is registered on the production tracking system for each bloom produced and

can be recovered from the historical data base.

Bloom laid down on the roller table just after weighting and punch marking is visible in the

following picture.

The system is installed just in front of the marking machines, so that just after weighting

the blooms are punch marked on the head and then proceeds to the de-burring, cooling

and discharging system.

2. Bloom marking system on transfer roller table With the aim of avoiding costly controls and bloom mixing the caster was equipped with

marking machines.

The marking machines are completely automatic and are punching o the heads of the

blooms suitable code, decided and modifiable by the Customer recording furnace used to

produce the liquid-heat number-billet number- strand.

The codes are defined automatically by the control system during proceeding of the

production and are punched and recorder in bloom SW historical data and quality control

system for any further analysis.

The appearance of head punch is shown in the following picture.

3. Bloom discharge system with possibility of selecting short blooms and to discharge to roller table dedicated to hot charging or bloom controlled slow cooling

The design of the discharge system has been made to allow billets and blooms to be

discharged to the cooling bed or to a roller table for immediate transportation and storage

to a pit for slow cooling dedicated for the crack prone high carbon and high alloyed steels.

On opposite side of the cooling bed a suitable frame has been designed to receive the

short billets or any billet not fitting the severe quality standards in force.

4. Bloom automatic SW for quality control and tracking system The full set of information available by all sensors and controls on the machinery are used

to provide on line monitoring of the process via software as already available on all up to

date casters.

In Izhstal all production parameters together with all surveyed parameters are thus

recorded from the field sensors and collected on the fly for every 10 mm slices of

bloom/billet to provide an historical record of data suitable for easy classification of all

materials produced (casting speed, temperatures, water flows, bloom temperature,

withdrawal pressures, cutting data, bloom weights, marked codes etc.).

Examples of Billet Tracking system pages from which the data are manageable are

reported here below.

MACHINE TEST PHASE AND PERFORMANCES

During erection the base mechanical equipment has been installed with perfect alignment

and leveling that was a must in this peculiar situation, moreover the additional equipment

mentioned above had requested additional effort during installation and setting up.

In the same period and before plant start-up a proper and full training with lessons have

been done covering the continuous casting theory, the machinery mechanical details and

the automation and controls, this to allow all operators to operate, manage and maintain

the machinery in the better way.

Even if only the specific details of the new machinery really needed some clarification;

since the metallurgical heritage of the plant operators and the full passion of all people

involved had really helped the preliminary and start-up phases of the plant.

Theoretical training has been then completed by practical operation on the caster during

cold testing period and during first hot testing, always done in full cooperation between

STS personnel and Izhstal operators.

After erection the machine cold testing procedure has been agreed and executed between

STS and Izhstal as per detailed protocol issued together and in full collaboration.

All measures, parameters, data sets, and details have been considered, verified and

tested to safely start production in the better way with the shortest possible learning curve.

With these premises the plant start-up took really limited amount of time, and after the first

cast with the presence of Mr. Putin the plant go on casting and passing satisfactorily the

preliminary phases of hot start-up.

Then the performance tests have been started according to contractual statements and

with sequence and procedure agreed between the parties.

For casting purposes the steel grades to be produced have been divided in groups/families

having similar behavior, so that the casting parameters can be defined for the families

grouping similar steels.

In this way the caster set up is easier and must be changed less frequently, the so called

“recipes” have been defined for all families in a comprehensive technological manual

submitted to the Customer in due time before the testing.

The wide range of steels to be produced did a little complicate this preliminary phase of

work and the number of families for Izhstal come out to be not so small, as per details

reported in the following table.

Steel GROUP

№

Type of Steel Specific Steel grades in Izhstal Production Program

Production 125x125

[t]

Production 140x180

[t]

1 Peritectic Steel 1a: 20Г, Св-08, Св-08ГА, Св-08ГС, Св-08Г2С, Св-08А, Св-08АА, Св-08ХГ2С, Св-10ГА, Св-10Г2, Св-12ГС, Св-08ХМ, 10, 15, 20, А11, А20, 09Г2С 1b: 12ХН, 12ХН2, 12ХН2А, 12ХН3А, 12Х2Н4А, 20ХН, 20ХН3А, 20Х2Н4А, 15Г, Св-06НЗ

50000 5000

2 Medium Carbon Steel

30ХН3А,40ХН, 45ХН,50ХН, 15ХГН2ТА, 19ХГН, 20ХГНМ, 40ХГНМ, 20ХН2М, 40ХН2МА, 25Г,35Г, 40Г,45Г, 50Г, 30Г2, 35Г2, 40Г2, 45Г2, 50Г2, 25Г2С, 25, 30, 35, 40, 45, 50, А12, А35, АС35Г2, А40Г, АС40, 17ГС, 20ГС

64000 18000

3 HIGH carbon Steel

65, 70, 75, 80, 85, 65Г, 70Г, С62D2-C98D2, 50Р, 55, 60, У7А, У8А, У8ГА

50000 12000

Steel GROUP

№

Type of Steel Specific Steel grades in Izhstal Production Program

Production 125x125

[t]

Production 140x180

[t]

4 4a: Steel Alloyed with

Cr/Cr-Si/Cr-Si-V/Cr-B-Mn

4b: Steel Alloyed with

Cr+Si+Ni

18ХГ, 18ХГТ, , 25ХГТ, 25ХГМ, 15ХМ, 20ХМ, 30ХМ, 30ХМА, 35ХМ, 38ХМ, 38ХМА, 40ХМФА, 25ХГСА, 30ХГС, 30ХГСА, 30ХГСН2А, 35ХГСА, 15Х, 15ХА, 20Х, 30Х, 30ХРА, 35Х, 35ХА, 38ХА, 40Х, 45Х, 50Х, 50ХГ, 20ХГР, 7Х3-9Х1, 15Г, 35Г, 50Г, 10Г2, 40Г2, 17Г-17ХГ, 35ГС, 20ХГСА 20ХНР, 20ХГНР, 20ХГНТР

89500 60000

5 Steel Alloyed with Cr-Mo

/Cr-Mo-Ni-V-Ti

15ХФ, 40ХФА, 47ГТ, C3D2-C60D2, АС38ХГМ, АЦ20ХГНМ

24000 40000

6 Steel for Bearings/

Tools

ШХ15, ШХ15СГ, ШХ20СГ, У9А, У10А, У11А, У12А, У13А

2500 9000

7 Spring and structutal steel

with Cr-Si

33ХС, 38ХС, 40ХС, 55С2, 55С2А, 60С2, 60С2А, 60С2Г, 65С2ВА, 70С3А

8000 4000

8 Stainless steel and

Cr-Ni steel of high treatment

АЦ20ХН, 08Х13, 20Х13, 12Х18Н10Т

2000 12000

For each one of the above groups specific information have been listed in the Operation &

Technological Manual for machine setting-up, casting parameters, and operations details.

The set of information and process data comprises synthetically the following:

tundish preparation procedures

tunsish pre-heating cycle& final temperature

tundish nozzle characteristics

covering powder type and adding procedure

mould lubricant (oil or powder) and addition procedure/quantity

Argon flushing procedure and set data

mould level set point and regulation

primary cooling water characteristics and set points

M-EMS set point data

oscillation frequency and stroke data

secondary cooling nozzle set-up

secondary cooling water characteristics and set points

F-EMS position and set point data

bloom exit temperature data

casting speed data

cutting torch pressures set points

cutting torches iron powder set points

bloom cut length data

bloom marking code

bloom weight set point

Some of the data are of course automatically set from the caster control system just by

selecting the steel grade and cast size on the recipes page on HMI.

The operators were in any case free to modify-enter-adjust the set point parameters on the

STS user friendly and very intuitive MHI interface.

And some adjustments were easily made during first testing from Izhstal operators or STS

with the aim of optimizing the bloom quality through fine tuning of set points & parameters

for the specific operative situation faced during performances testing.

The requests of quality were in fact so tight that every aspect of operation and process

was analyzed, tested and finally set for the best result.

A short summary of the guaranteed parameters that have been considered during testing

phase is reported here below.

GUARANTEED PARAMETERS

Type of Parameter Notes

General Parameters

Number of heats and sections definition of requested number of heats for each cast size for performance tests

Section sizes and steel grades definition of the specific steel grades to be used for performance tests as selected from each group

Casting Speed

Casting yield

Productivity tests

Dimensional Tolerances Figures

SIZE OF CROSS SECTION

FACE BULGING / DEPRESSION

RHOMBOIDITY (square sections)

BILLET LENGTH

BILLET STRAIGHTENESS

BILLET TWIST

Surface Quality Requests

MACROSTRUCTURE

AXIAL (CENTRE) POROSITY

CENTRE CARBON SEGREGATION

EQUIAXED ZONE

LIGHT CONTOUR (WHITE BAND)

INTERNAL CRACKS

NITROGEN PICK UP

Casting Machine Tests

Re-stranding time

Tundish life and sequence

Mould changing time

Time for section change

Of course all the above guaranteed parameters had to be tested and verified for both cast

sizes and for select specific steel for each steel group.

The steel grades finally selected for testing are reported here below, and are covering

practically each family of steel today in production, represented by the most critical specific

variants.

Steel

Group Steel Type

Specific

Steel Grade

for Test

Heats

Number

of Test

Heats

Billet/Bloom

Section

[mm]

Casting

Mode

2

Medium Carbon

Steel – Alloyed with

Cr Ni and Ti

15ХГН2ТА 2

125х125 Open &

Protected

stream 140х180

4a

Alloyed Steel –

Alloyed with Cr Mo V

and Ti

18ХГТ 2

125х125 Protected

stream 140х180

7

Spring Steel –

Alloyed with C and

Si

60С2 2

125х125 Protected

stream 140х180

6 Steel for Bearings –

Alloyed with high Cr ШХ15СГ 2

125х125 Protected

stream 140х180

4b

Alloyed Steel –

Alloyed with Cr Ni

and Ti

20ХГНТР 2

125х125 Protected

stream 140х180

1a Peritectic Steel Св08 2 125х125 Protected

stream 140х180

1a Peritectic Steel 09Г2С 2 125х125 Protected

stream 140х180

8 Free Cutting Steel –

Alloyed with hhigh S АЦ20ХН 2

125х125 Protected

stream 140х180

8 Austenitic Stainless

Steel 12Х18Н9 2

125х125 Protected

stream --

And even if the stainless steel was not initially introduced in the steel grades selected for

testing we finally agreed to insert al this for completeness and full satisfaction of both

parties in machine testing.

So the testing period last some months, ad during that period more than 500 heats have

been cast.

The surface quality of the billet was immediately good and only small internal cracks on

some of the more critical grades required some tuning.

Finally all requested figures were met with complete satisfaction.

Typical cross sections of some representative sample blooms are reported here below for

information.

Rectangular Bloom 140x180mm Peritectic Steel Св08

Rectangular Bloom 140x180mm Alloyed Steel – Alloyed with Cr Ni and Ti 20ХГНТР

CONCLUSIONS

The strategic new caster in Izhstal was a challenge for the Mechel group, investing in one

of their most important and historical sites, pushing forward for progress aiming to very

important targets for both production and quality.

The wide range of steel grades to be produced and the high quality targets could had been

out of any doubt the best “test bench” for everybody in this field.

And the challenge was picked up from STS with respect in front of such a big group and

stringent performances requests, but also with the strength and the determination of a

small company full of passion.

STS knows that his standard continuous casting machine, as developed internally since

years, simple, sturdy and maintenance free, could meet the highly demanding requests of

Izhstal.

STS knows also that the flexibility of design of this machine gives the possibility to

accessorize and complete the machinery for the most critical and stringent production and

quality requests.

The so completed casting plant, fully accessorized on demand for this specific project, was

thus installed and started up successfully thanks also to the help of prepared personnel of

Izhstal.

The hot phase and the performance tests took reasonable time to cover the wide range of

steel and casting conditions, and finally all the requests were fulfilled for the complete

satisfaction of the Customer.

This caster is the practical success and example how the long tradition of STS machinery

designed to reduce maintenance and increase reliability can be equipped, even step by

step, with the most advanced features to meet the most critical quality requirements.