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АНИЗОТРОПНАЯ ЭЛЕКТРОТЕХНИЧЕСКАЯ СТАЛЬ

 

RUS-CORE*

(Grain Oriented Steel for Transformer Cores)

Novo-Lypetsky Metallurgical Company (NLMK)

GO-manufacturing facilities located in Lypetsk and Ekaterinburg, Russia

 
  • RUS-CORE is being registered as a trademark.  At this time it’s a tentative name. 

Presently, electronic version of this catalogue is available at www.queencitysteel.net

 
 

 

 

 

 



FOREWORD

 

In December of 2005 the Russia’s fourth largest metallurgical company – NLMK – acquired VIZ-Stal, which specializes exclusively in silicon steel.  The acquision created one of world largest producers of Grain Oriented silicon steel (GO), with annual output of more than 320,000 tons.  

Last year, NLMK initiated a major Investment Program to modernize the equipment and processing technologies on both production sites: in Ekaterinburg (VIZ-Stal) and Lypetsk (NLMK).  Upon completion (2010-2011), this will reinforce NLMK’s position as a world leader in producing high quality GO by adding High Permeability steel (HiB) to the wide range of regular grades (RGO) produced today.

Presently, NLMK supplies regular (R) and selected (S) grades of GO in 0.23 – 0.50 mm range of gauges (trademarks: RUSCORE-R and RUSCORE-S).  Production of domain refined high permeability GO with ultra-low core loss (RUSCORE-D) is planned to begin in 2010.

NLMK has an established network of trade offices worldwide and all the logistics to ensure timely supply of GO in coils (up to 1000 mm wide), slit to width strips and cut to length sheets directly to customer’s doors.  Any grade of silicon steel listed in this brochure is tested and certified in accordance with one of the major International Standards and/or as required by customer’s Technical Specification (after confirming specific quality parameters with NLMK sales representative).

 

1.                 Delivery Formats, Gauges, Dimensions

 

Delivery Formats

Geometry Parameters

Gauges and Sizes, mm

RUSCORE-R

RUSCORE-S

Coils and Strips

Thickness

0,23; 0,27;0,30; 0,35; 0.50

0.27; 0.30

Width

Coil

930;970;1000 *)

Strip

50 - 500, (with 10 мм increments)

Coil and Strip ID

508-512

Sheets

Width and thickness

Same as for coils and strips

Length

1500 - 3000

*)   Coils over 1000 mm wide supplied with mill edge (no burr height guarantee), so that edge trim by the customer is required prior the steel can be cut into core laminates.

 

2.       Technical Characteristics fo RUS-CORE grades

 

2.1              Typical Magnetic Properties 1)

 

Grade 2)

Nominal 3) Thickness,

mm

Specific Core Loss 4)

W,  В/кг

Flux Density, B,

Тeсла

1.5/50

1.7/50

В8

В25

NV23S

0,23

Properties defined depending on intended use by the customer

NV27P-100

0,27

0.70

0.99

1,89

1,96

NV27S-105L

0.72

1,04

1,87

1,95

NV27S-110

0,75

1,08

1,87

1,94

NV27S-120

0,80

1,18

1,86

1,94

NV27S-130

0,84

1,27

1,85

1,94

NV27S-140

0,89

1,36

1,85

1,93

NV30P-105

0.30

 

0.73

1,04

1,88

1,95

NV30S-110L

0.76

1,08

1,87

1,94

NV30S-120

0,80

1,18

1,86

1,94

NV30S-130

0,85

1,27

1,85

1,94

NV30S-140

0,89

1,36

1,84

1,93

NV35S-120

0.35

0,90

1,19

1,87

1,94

NV35S-130

0,94

1,27

1,86

1,94

NV35S-145

0.99

1,40

1,85

1,93

NV50S-150

0,50

1,42

2.00

1.84

1,91

NV50S-200

1.60

2.30

1.82

1,90

 

 Notes:     1)   Guaranteed values (maximum for Core Loss and minimum for Flux Density) provided    for  individual coil,  average guaranteed values provided for one shipment and for the  whole contract, depending on the order size (statistical analysis is used).

2)       Grades with indices S and P certified by Epstein method (IEC 60404- 2:1996), grades with index L – by Single Sheet method (IEC 60404-3:1992).   Grades with index L shall not be used to produce laminations and cores subject to stress rellief anneal

3)       For thickness, the typical (actual) values presented in section 2.3 of this brochure.

4)    Core Loss at 60 Hz = Core Loss at 50 Hz x 1.31

                         

2.2              Magnetic properties vs. Flux Density (B) and Field Strength (H) 

Graphs for W=f(B) and VA=f(B) for some of the grades listed in the above table presented at the end of this brochure.  Polynomial equations for W=f(B) and VA=f(B), as well as graphs for B=f(H), emu = f(B), and H/m = f(B)  may be requested through our local sales offices. 

 

2.3      Thickness, Width, Mechanical, and Physical Properties

  

Nominal thickness

(mm)

Thickness,

microns

Stacking Factor,

%

Hardness

Number

of bends

HV5

HR30

Typical

+/-

Typical

Mini-

mum

Aver-

age

Range

Aver-

age

Range

Typical 1)

0.23

226

10

95.0

94.5

190

186-193

75

73-78

>10

0.27

262

10

95.8

95.0

186

182-190

74

71-77

>10

0.30

293

10

96.4

95.5

183

180-186

73

69-76

>10

0.35

341

15

97.0

96.0

177

173-182

71

68-73

>10

0.50

483

30

98.2

96.5

175

170-178

70

67-72

>10

1)      Guaranteed value = 1

 

Nominal thickness

(mm)

Yield Strength, N/мм2

Tensile Strength, N/мм2

Along RD

Across RD

Along RD

Across RD

Aver-age.

Range

Aver-age.

Range

Aver-age.

Range

Aver-age.

Range

0.23

330

315-345

350

337-362

359

354-365

402

393-407

0.27

326

312-340

345

330-360

354

350-360

395

388-400

0.30

320

310-330

340

325-355

350

345-355

390

385-396

0.35

314

305-325

333

320-345

345

335-353

384

379-388

0.50

305

290-320

325

315-335

340

330-350

380

373-384

 

Nominal thickness

(mm)

Camber, mm

 

Burr,

micron

Waviness,

maximum

Width tolerance,

mm

 

Residual Stress

(deviation from straight line after cut along RD)

%

мм

0.23

</= 0.5

for 1500 mm long samples

< 20

(except coils with mill edge)

1.0

2.0

< +0.8 for

width > 500 мм;

< +0.5 for

width = 250 – 500 мм

< +0.3 for

width < 250 мм.

</= 1.0 мм.

Measured only for strips > 500 mm

0.27

0.30

0.35

0.50

 

 

Nominal thickness

(mm)

Density

кg/м3

Specific

Resistivity

mOhm/см3

Elongation, %

Ageing corefficient,

К 1)

Along RD

Actross RD

Average

Range

Average

Range

%

0.23

7650

48-49

20

16-24

45

40-49

<2

 

0.27

18

15-22

43

38-46

0.30

16

13-20

40

36-42

0.35

15

12-18

37

33-40

0.50

12

9-16

32

28-35

<3

1)      К=100*(W2-W1)/W1,  where W1  = core loss before and  W2 = core loss after the Epstein sample is annealed for 24 hrs at 225 oC  (according to EN 10107:2005)

 

.3.    Insulation Coatings

 

3.1 General information.

RUS-Core steel is supplied with one of three types of coating:

-          Conventional, designated CC (Coating Conventional)

-           Stress Coating, designated CM (Coating to lower Magnetostriction)

-           Soft Coating, designated CS (Coating Soft).

СС и СМ coatings applied on ECOMAG-Core grades intended for stacked and wound cores produced by slitting and cutting the steel strip (with disc or guillotine knives), while CS is typically1) applied on GO 0.5 mm, which is intended mainly for punching of laminates for magnetic circuits of large generators and motors or for small cores (used in appliances) with E and I shaped laminates. 

While technologically the СС и СМ coatings are similar to С5 + С2 type (ASTM designation), their chemistry differs in such a way that СМ has coefficient of thermal expansion ~ half that of CC. As a result, CM induces higher tensile stress in the steel, which leads to lower core loss and reduces sensitivity to stress, introduced during core manufacturing.  In addition, CM reduces acoustic noise in stacked cores (by 2-4 dB at operating flux density = ~ 1.7 Tesla).

Properties of CS coating are similar to that of С4 – type coating (ASTM designation). 

 

3.2 Typical Technical Characteristics of Insulation Coatings

 

Type of coating

Franklin Resistance 1)

(coil average)

Thickness per surface

Adherence after bend over  20 mm radius 2), 

% undamaged, per side

Ability to withstand thermal treatment in protective atmosphere

Ohm*см2

micron

Convex

Concave

Hrs at Т , оС

CC

> 20

2-3

100

> 90

> 10 при 800-900

CM

> 30

2-3

100

> 90

>10 при 800-900

CS

> 5

1-2

100

100

</=0.5 при </= 750

1)         Calculated according to IEC 60404-11:1991, after measuring Franklin current, IF. RF= 6.45*(1/IF –1).

2)       On customer’s request, adherence can be tested for other bending radii (e.g., 10 or 30 mm).

 

 

 

 

 

 

 

4.  Quality Assurance (main elements)

NLMK incorporates complete cycle of steel-making operations: from charge preparation to testing and packaging finished GO coils, strips and sheets.   All production processes for Rus-Core are subject to consistent and uniform quality control procedures, which certified according to ISO 9001-2000.   Considering the critical importance of hot band processing to obtain consistency of magnetic properties of the final product, manufacturing process is organized in such a way that one hot-rolled band is processed as one piece (“master coil”) from pickling to flattening anneal.

 

4.1 Control of Magnetic Properties   

Production of RUS-Core steel of given nominal gauge follows very similar processing steps, which requires thorough monitoring of magnetic quality to determine actual grade to which the finished coil shall be certified.   Four-step procedure is used to achieve statistically sound grade designation for coils with the same nominal gauge.

First, magnetic permeability is continuously monitored along the whole length of a master coil immediately after flattening anneal.

Second, specific core loss (Single Sheet method) and Franklin currents are measured on samples from both ends of the master coil (also after flattening).

Third, samples are cut from both ends of each finished coil (typically, two finished coils are produced from the master one) and tested in SST, which provides information for preliminary grade designation.

Finally, the coil grade certified, using the core loss value for Epstein test from the end, which corresponds to the worst SST result.

            While Epstein test is used to determine actual grade for all coils, except the ones with domain refined (have index L in grade designation), data measured with SST method can be included in quality certificate (if requested by customer).  The guaranteed values (individual coils) and typical values (shipment and contract) shall be agreed between customer and supplier. 

All guaranteed, typical and average magnetic characteristics as well as Standard Deviations (for shipments no less than 10 coils) are derived from statistical analysis of actual production for 3 to 6 months preceding certification process. 

 

4.2    Other Quality Parameters.

 All quality parameters monitored and measured according to QA manuals, which comply with ISO 9001-2000, major international standards and Russian national Standards (GOST).  In some cases, quality control procedures may be modified or added, if customer has specific requirements, which the mill is capable to satisfy.  Several procedures for quality parameters our customers consider as most relevant ((besides magnetic properties) are commented below in some detail.

 

Franklin current, IF, which used to calculate coating’s Resistance, RF, is measured for both ends of master (immediately after flattening anneal) and finished (full width, before trimming or slitting).  Every time IF is measured in eight test points (two per surface on each end) and the coil is certified using average value of RF, derived from measured IF.  If requested by customer, minimum RF value or maximum IF value (out of eight test points) can be used as certification parameter.

            Coating thickness is measured periodically to ensure 2 to 3 microns of ceramic oxides on each surface for CC and CM coatings and 1 – 2 microns of semi-organic compound on each surface for CS coating.

            Strip thickness is continuously monitored during cold rolling and finishing operations.  The data for each finished coil stored (in digital format) for 6 month after the coil is shipped and it’s available to the customer on request.  For certification, actual thickness is calculated for two ends of each coil using equation: t = m/(w*l*r), where m, w, l represent mass, width and length of single sheet sample (used to test specific core loss) and r = assumed steel density = 7.65 g/cm3.   If necessary, quality certificate may include value of maximum thickness deviation along the coil (from continuous thickness monitoring of the finished coil)

            Burr height is guaranteed not to exceed 20 micrometers (mm) for strips slit at the mill to customer specified width (< 750 mm).  For wider strips the same limit is guaranteed when customer specifies that the steel will be cut into core laminates without trimming.  In other cases, strips wider than 750 mm supplied with burr height =/< 30 mm.  For strips slit at the mill for cores of large power transformers, burr height </= 10 mm is guaranteed for 95% of the strips length and </= 15 mm for the whole order.

4.3    Quality Certificate

Typical format of Quality Certificate (QC), which is provided to the customer with each shipment of RUS-Core steel presented below.  On customer request, the QC may include data for other technical characteristics, such as: specific core loss tested at 60 Hz, value of specific apparent loss (exciting power, VA/kg), values per pound instead of kilogram, core loss and/or exciting power at customer-specified flux density, actually measured Franklin current instead of calculated Franklin resistance, maximum thickness deviation, etc.  

 

              NLMK/VIZ-Stal

EXPORT

QUALITY & QUANTITY CERTIFICATE

Manufacture:                                                                              Package: Metallic case

Contract #:                                                                                  Coating:  CC

Purchase / Order #:                                                                    Lamination factor:

Description of goods: COLD ROLLED GRAIN ORIENTED

                                              SILICON STEEL. PRIME, COILS                R wagon:

Standard                                                                                       RB/L:

 

Grade

 

Mill and shipping coil numbers

Width, mm

 

Weight

Magnetic values for the worst end of a coil

Franklin Resistance,

average per coil.

 

 

 

Thickness,

Actual value,

microns

 

 

Core Loss, W/kg

@ 50 Hz and B=

Flux Density

В8,

 

 

Gross

Net

1.5 Т

1.7 Т

Тесла

Ohm.cm2/

lamination

Front

Back

1

2

3

4

5

6

7

8

9

10

11

 

12

NV27S-110

103554

07905-2

970

4520

4430

 0.77

1.08

1.87

35

    264

 

259

NV30S-120

205543

07910-1

980

4160

4070

 0.81

1.17

1.87

52

    287

 

293

 

Total:                                                                                                  Signature        

Number of coils:                                                                                 Stamp

 

Date:

   

 

Following pages contain graphs for typical dependence of Core Loss (W/kg) and Exciting Power (VA/kg)  on Flux Density (Tesla) at 50 and 60 Hz. 

Similar graphs for all other grades, as well as graphs for DC Magnetization, Magnetic Permeability and Exciting Force for ALL grades listed in Table  2.1 (see above) are available upon request, which shall be addressed to our local sales office.


















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