Sistemska tehnika

FORGED PRODUCTS FOR ALUMINIUM INDUSTRY

Shells for continuous casting produced by Sistemska tehnika enable optimal casting speeds, maximal casted ton-nage per campaign, minimal crack appearance, minimal crack progres-sion and low, evenly distributed rough-ness of the casted material’s surface. Our customers experience up to 25% increase in the tonnage of the casted material in comparison to their average supplier’s mixed performance.

This is achieved by using specially developed proprietary

steel grade combined with our own heat treatment. All of

the heat treatment equipment was developed, designed

and produced in-house together with appropriate technol-

ogy. The results show optimal characteristics of our shells

such as high heat conductivity and resistance to thermal fa-

tigue. Microstructure of shells for continuous casting is opti-

mized during the production process. Final microstructure

of shells consists of determined relation between tempered

martensite and finely dispersed carbides.

Steel grade for shells was developed by our experts,

specifically for the needs of non-ferrous industry. Besides

optimal content of chemical alloys it is also characterized

by the lowest possible levels of trace elements. In addition

to high cleanliness, steel is also homogenized, which

further improves mechanical characteristics. We guarantee

the same material properties from start to scrap diameter.

ST shells for continous strip casting

Chemical composition of steel PO209:

PO209 C Mn Cr Mo V Ni

Max 0,25 0,40 2,00 0,80 0,20 0,20

Min 0,50 0,80 4,00 1,80 0,50 0,60

2

3

Mechanical properties:

Hardness (HB): 380 – 420

Yield strength (MPa): 1150

Impact strength (J): avg. 55*

Grain size (acc. ASTM E112): min. 7

Thermal conductivity (Wm-1K-1): 39

Thermal coefficient of 20 – 200 °C 20 – 400 °C 20 – 600 °Clinear expansion (10-6 °C-1): 12,2 13,3 13,6

* KU2 specimen according to EN ISO 148-1

UHP / EAF 40 T

FORGING

HARDENING

GRINDING AND MT(EDDY CURRENT CINTROL)

VAD

CUTTUNG

TEMPERING

DIMENSION CONTROL

INGOT

ROUGH TURNING

HARDNESS CONTROL

HARDNESS CONTROL

PUNCHING

ULTRASONIC AND MAGNETIC CONTROL

TURING

PACKAGING OROVERSEAS PACKAGING

Flow chart representing the production of shells for continuous strip casting

VD + LF

QUENCHING TURNING

UHP / EAF 40 T INGOT PUNCHING

ULTRASONIC ANDMAGNETIC CONTROL

ROUGH TURNINGCUTTINGFORGING

TURNINGHARDNESS CONTROLTEMPERINGQUENCHING

GRINDING AND MT (EDDY CURRENT CONTROL)

DIMENSION CONTROL HARDNESS CONTROL PACKAGING OROVERSEAS PACKAGING

4

5ULTRA CLEAN STEEL Nonmetallic inclusion in trace (acc. DIN 50602 met. K1 < 10)

Homogeneous microstructure: Tempered martensite and equally distributed fine carbides.

JOMINY TEST HARDENABILITY (the Jominy end quench test)

00

60

50

40

30

20

10

2010 30 40 50 60 70

Har

dnes

s [H

Rc]

Depth [mm]

Forged rolls for cold rolling of non-ferrous alloys produced by Sistemska tehnika fulfill the customer’s demands for increased productivity, high reli-ability, safety of operation, finer sur-face quality, higher rolling speeds, and more demanding rolled materials and thus positively influence TCO (Total Cost of Ownership).

This is achieved by combining the best steel grades, state-

of-the-art heat treatment, precise machining, multi-step

inspection of each roll, and continuous investments in the

development of new qualities. Our forged rolls withstand

high area pressure and are characterized by highly uniform

hardness of +/-0,5 HRC throughout the working barrel and

a very homogenous microstructure. We guarantee that the

minimum hardness drop throughout the hardened layer is

up to max. 3%.

ST forged rolls for cold rolling mills

Microstructure of induction hardened layer is low tempered

martensite and small carbides

Microstructure of induction hardened layer is low tempered

martensite and small carbides

6

7

With each shipment the customer receives the inspection certificates and the quality guarantee.

Optimal mechanical characteristics are achieved by using our proprietary heat treatment. Rolls

are quenched and tempered to basic hardness and then surface hardened to achieve optimal

working hardness. This is done by using our own bi-frequency induction technology and equipment,

developed, designed and produced in-house. Dual induction frequency (50-100 Hz, 500-1000 Hz)

is continuously variable. Therefore several case depths up to 60 mm are possible. To achieve the

best mechanical characteristics also on roll necks, we use our own award winning 3-D induction

hardening machine. Here also the induction frequency is manually adjustable (2.8 kHz- 25 kHz)

with several possible case depths. Induction hardening is followed by cryogenic treatment. This is

an additional step in the heat treatment hardening process. It completes the transformation of the

steel’s microstructure from austenite to the stronger and harder martensitic structure. The hardness

of the steel increases along with increasing the percentage of martensite in the structure. Hence,

wear resistance increases as it correlates positively with hardness. Wear resistance, in addition,

depends on the presence of carbides.

To ensure the highest quality possible, each roll is inspected six times throughout the production

process. In addition, we measure levels of retained austenite and residual stresses to guarantee

the highest reliability and safety of operation. For this operation we use an accurate and safe X-ray

diffractometer for measuring residual stresses and retained austenite contents. Xstress measures

the stresses on crystalline material by X-rays, based on the phenomenon known as Bragg´s law.

Steel grades:

Ravne brand name

OTV1C

OTV2C

OTV1D

OTV1B

OTV2B

Comparison of main properties:

Grade Wear resistance Hardening layer Max. Roll diameter Toughness

OTV1C

OTV2C

OTV1D

OTV1B

OTV2B

Roll nomenclature

3 % Cr steel

3 % Cr steel

4 % Cr steel

5 % Cr steel

5 % Cr steel

C

0,80

0,80

0,83

0,80

0,80

Si

0,85

0,85

0,80

0,80

0,80

Mn

0,6

0,6

0,4

0,3

0,3

Mo

0,5

0,5

0,5

0,5

0,5

V

0,1

0,1

0,1

0,1

0,1

Cr

3,0

3,0

4,0

5,0

5,0

3

Forged rolls for cold rolling of foil produced in Sistemska tehnika are suitable for the highest rolling speeds and loads. They fulfill the highest demands for surface quality and enable high quality and high speed rolling of foil, down to 6 microns.

ST forged rolls for foil

Microstructure of induction hardened layer is low tempered

martensite and small carbides

Microstructure of induction hardened layer is low tempered

martensite and small carbides

8

9

Steel grades:

Ravne brand name

OHV4

OHV5

OTV1C

OTV2C

Comparison of main properties:

Grade Wear resistance Hardening layer Max. Roll diameter Toughness

OHV4

OHV5

OTV1C

OTV2C

Rollnomenclature

2 % Cr steel

2 % Cr steel

3 % Cr steel

3 % Cr steel

WR. NR.

1.2327

1.2375

/

/

DIN

86CrMoV7

83CrMoV9

/

/

C

0,80

0,88

0,80

0,80

Si

0,80

2,10

0,85

0,85

Mn

0,30

0,35

0,60

0,60

Cr

5,0

2,1

3,0

3,0

Mo

0,5

0,3

0,5

0,5

V

0,1

0,1

0,1

0,1

Experts of Sistemska tehnika have, together with its steel producer, developed a special ESR

technology for production of ultra clean steel grades, optimized for cold rolling of foil. Second

refining, combined with our heat treatment technology gives optimal results in terms of:

- The cleanest steel on the market (DIN 50602 method K, K1<5),

- Dense structure without porosity, higher cleanliness, homogenous structure

and chemical analysis over the whole roll,

- Uniform hardness on the whole working surface of the roll within the tolerance

range of +/-0,5 HRC,

- Minimum hardness drop throughout the hardened layer up to 3%,

- Concentricity between the barrel and bearing seats in tolerance <=0,005

or if required <=0,002 mm.

5 4 4 1 9 25

2540

Quality from the beginning

Tradition, experience, knowledge

and quality assurance make us

a reliable partner. Our strategic

supplier and few additional

international suppliers form a

carefully selected and regularly

checked procurement network.

Complete technology support and cooperation

We are here for you … Sistemska

tehnika is an ideal partner for

a cooperation in the field of

development, production and

assembly of metallurgical

equipment and components on the

basis of your documentation.

Efficient sales networkSistemska tehnika has developed

an efficient sales network to give

our customers full technical and

commercial support when and

where they need it: We think global,

but act local.

Excellent logistics Sistemska tehnika is located in

the heart of Europe and is part

of an international logistics

group. This gives us an excellent

international accessibility.

Sistemska tehnika d. o. o. Koro�ka cesta 14, SI – 2390 Ravne na Koro�kemSlovenia

Phone: +386 2 870 7606Fax: +386 2 870 7605

Url: www.st-ravne.si/en

E-mail: salesast-ravne.si

9/2015