Symposium Steel in Hydropower, Dillingen 7 th April 2011 1

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High Strength Steel in Hydropower:Production and Application

AG der Dillinger Hüttenwerke Martin Steffen

Contact:Martin Steffen66748 DillingenPostfach 1580Phone: +49 6831 47-3455Fax: +49 6831 47-3089martin.steffen@dillinger.biz

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Content

• Introduction

• Production

• Delivery conditions

• Delivery possibilities and application in Hydropowe r

• TM processed high strength steel DILLIMAX500ML

• Calculating Example

• Application of high strength TM material of DILLIMA X500ML type

• Conclusion

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High Strength Steel – What´s that?

End of 1920: Introduction of the steel grade St52 (S355) for bridge-building (Prof. Klöppel)

→→→→ St52 was called a high strength steelfor a long period

Now: S355 is a standard material for bridge-building

→→→→ Definition of „high strength“ depends onthe technical developement

Today´s Definition: high strength steel⇔

Steel with ReH > 355 MPa

Definition of high strength steel

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High Strength Steel

weight reduction economical processing

General Advantages of high strength steel

X-weld

S23

5

S69

0

ratio ratioYield strengthPlate thicknessAmount of weld metalCost of weld consumableAuxilliary weld costWeighed welding cost

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Coking plant

Sintering plant

Blast furnaces

Desulphurisation

Steel mill

Converter

Vacuum treatment

Ingot casting

Continuous casting Rolling mill

Production

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DELIVERY CONDITIONS

Delivery Conditions

AR N Q+T TM

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Delivery Conditions

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hot rolling

Delivery Condition AR (as rolled)

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hot-rolling + Normalising

Delivery Condition N

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hot-rolling Quenching + Tempering

Delivery Condition Q+T

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Carbon solvedin the lattice Austenite

Ferrite + Cementite(Carbon can leave

the lattice)

[°C]

1390

910

slowcooling:

Ferrite+

Pearlite

fastcooling:

Martensite

Martensite(Carbon staysin the lattice,

distorted structure)

Q+T: the effect of quenching

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Typical applications of Q+T steels

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ThermoMechanical rolling

Delivery Condition TM

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TM Fine grain

Grain size ↓

Hall-Petch:

Strength ↑

Toughness ↑

Excellent weldability+

TM (ACC)Normalised TM (air)

Aims of TM processing

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Differentiation between normalising rolling and TM(CP)

Normalising rolling:

rolling process in which the final deformation is carried out in a certain temperature range leading to a material condition equivalentto that obtained after normalizingso that the specified values of the mechanical properties are retained even after normalizing

Thermomechanical rolling:

rolling process in which the final deformation is carried out in a certain temperature range leading to a material condition with certain properties which cannot be achieved or repeated by heat treatment alone

• material has to be suitable for a furnacenormalising in the delivery condition

• heating above 580°C may impair tensileproperties if such conditions are foreseensupplier should be notified in advance

Remark:in international publications you may find both pro cesses referred to as „controlled rolled“

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N (+T)

Q (+T)

TM

Plat

e w

idth

[mm

]M

ax. plate length: 28 m

Max. plate w

eight: 40 t

Plate thickness [mm]N = normalising, normalised rolledTM = thermomechanically rolledQ = quenchedT = tempered

Plate dimensions outside this production range may be feasable upon special agreement, but restrictions may apply for certain grades/requirements.

General delivery programme for different delivery conditio ns

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200

250

300

350

400

450

500

550

600

650

700

0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375

Plate thickness [mm]

Yie

ld S

tren

gth

[MP

a]Hydropower : actual application, thickness vs. yield strength

NTMQ+T

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Reference thickness 50 mm

Tensile Requirements (transversal)

ReH: ≥490 MPa / Rm: 610 - 750 MPa / A5: ≥ 17 %

Toughness Requirements (transversal)

at -50 °C ≥ 30 J

Chemical Composition

For the ladle analysis, the following limiting values are applicable:

Alloying Concept

low carbon content (C < 0.09), microalloying with Nb

Carbon Equivalent: CE(iiw) – 0.45 CET – 0,30 Pcm – 0.24

Plate design of DILLIMAX 500 ML

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typical microstructure - 32 mm

Quarter plate thickness

Ferrite grain size acc. to

ASTM E112 - Table 2:12-13

DILLIMAX 500 ML

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Mechanical properties of DILLIMAX 500 ML

20 - 50 mm thickness

0

5

10

15500 520 540 560 580 600 620 640

Yield Stress Rp0,2 [MPa]

Pro

ba

bili

ty [

%]

600 620 640 660 680 700 720 740 760

0

2

4

6

8

10

12

14

16

Tensile Strength Rm [MPa]

Pro

ba

bili

ty [

%]

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0

5

10

15

20

25

30

35480 500 520 540 560 580

Yield strength Rp0,2 [MPa]

Pro

ba

bili

ty [

%]

600 620 640 660 680 700

02468101214161820

Tensile strength Rm [MPa]

Pro

ba

bili

ty [

%]

51 - 80 mm thickness

Mechanical properties of DILLIMAX 500 ML

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20 < t <= 50 mm

0,76 0,80 0,84 0,880

4

8

12

16

20

24

28

32

Yield to Tensile Ratio Rp0,2/Rm

Pro

ba

bili

ty [

%]

16 18 20 22 24 26 28 300

5

10

15

20

25

30

35

40

Pro

ba

bili

ty [

%]

Elongation A5 [%]

Mechanical properties of DILLIMAX 500 ML

20 - 50 mm thickness

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0

5

10

15

20

25

25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450

CVN longitudinal (-50 °C, average), J

rela

tive

freq

uenc

y, %

Toughness level of DILLIMAX 500 ML

MW: 244,3 J1s: 51,5 Jn: 145Min: 125 JMax: 353 J

12 - 50 mm thickness

High resistance against brittle fracture

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Toughness level of DILLIMAX 500 ML

High resistance against brittle fracture

0

10

20

30

40

50

60

25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450

CVN longitudinal (-50 °C, average), J

rela

tive

freq

uen

cy, %

57 mm thickness

MW: 296,3 J1s: 19,0 Jn: 100Min: 211 JMax: 332 J

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Processing

Welding: Toughness in HAZ

FCAW

SAW

0

50

100

150

200

250

300

350

Fusion line

FL + 2 mm

FL + 5 mmCha

rpy-

V e

nerg

y A

vat

-40

°C [J

]

0 1 2 3 4Heat input Q [kJ/mm]

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Reh [MPa] Rm [MPa]

S355J2 345 470 to 630S460M 440 540 to 720DILLIMAX 500 ML 490 610 to 750S500Q 500 590 to 770S550Q 550 640 to 820S690Q 690 770 to 940

Calculation example based on S355 in 40mm thickness

Basic tensile properties up to 40mm plate thickness as per standard or data sheet:

Calculating design values: 1) minimum of R eh and 0.7 x Rm

2) minimum of R eh and 0.8 x Rm

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Design values calculated as minimum of R eh and 0.7 x Rm

0

100

200

300

400

500

600

700

S355J2 S460M 500 ML S500Q S550Q S690Q

yiel

d st

reng

th /

desi

gn v

alue

[MP

a] unused potential

design value

unused potential

design value

Dillimax500 ML

S355J2 S460M S500Q S550Q S690Q

[40 mm] [35 mm] [31 mm] [29 mm] [24 mm][32 mm]

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[MP

a]Design values calculated as minimum of R eh and 0.8 x Rm

0

100

200

300

400

500

600

700

S355J2 S460M DILLIMAX500 ML

S500Q S550Q S690QDillimax500 ML

S355J2 S460M S500Q S550Q S690Q

[40 mm] [32 mm] [28 mm] [27 mm] [22 mm][29 mm]

unused potential

design value

unused potential

design value

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Pipes for a Penstock-lining

High plate thickness / Welding done under severe conditions

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Application

Lang Tan Laxiwa Hydro (China)

6 x 700 MW hydropower plantLocation: Yellow RiverDelivery: about 4,750 tGrades: S550QL, S500M,

DILLIMAX 500 MLThickness: 25 - 190 mm

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Yixing (China)

4 x 250 MW Francis turbines for pump

Delivery: 220 tGrades: DILLIMAX 500MThickness: up to 100 mm

with Z-properties

Application: bifurcations

Application

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Hydro Power Plant Kárahnjúkar, IslandHead: 420 mPower: 690 MegawattPlate thickness: bis zu 150 mmDH-delivery: 5,330 tSteel grade: S355ML, S420ML,

S460ML, S690QL1

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Mayflower TIV I

Jack-up installation for offshore-windmills

Delivery: 5,300 tGrades: DILLIMAX 500M

Thickness: up to 150 mm

(over 75 mm in Q+T)

Application

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Conclusion

• the definition of high strength steel is time depen dant

• each hydropower project is individual

• a wide variaty of steel grades is needed

• different requirements call for different steel sol utions

• DH can offer a wide range of solutions

• individual steel design should be discussed

• out of the many possible grades especially high str ength

TM processed steels show special benefits

• safe welding can be performed in a big working rang e