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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 [email protected]
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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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yiel
d st
reng
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desi
gn v
alue
[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