Manufacturing of advanced Rotor Forgings for Highly ... 1520 Donth.pdf · Introduction Development...

© 2011 Saarschmiede GmbH Freiformschmiede

8th International Charles Parsons Turbine Conference5 - 8 September 2011, Portsmouth, UK

1

Manufacturing of advanced Rotor

Forgings for Highly Efficient Fossil

Power Plants

B. Donth

N. Blaes

D. Bokelmann

Saarschmiede GmbH Freiformschmiede

Völklingen, Germany



2

Introduction

Development of the creep resistant steel grades FB2 and FB4

9-12% Cr Steels for Steam Temperatures 620°C

Boron-free and boron-containing steel grades

Manufacturing of turbine rotor forgings in steel grade FB2

Pilot turbine rotor

Commercial turbine rotor parts

Manufacturing of trial rotor forging in steel grade FB4

Manufacturing

Testing

Summary and Conclusions

Content



3

Efficiency of Coal Fired Power Plants

Coal maintains to be a major source for future power generation

CO2 emissions must be reduced for the protection of the climate

Combination of increasing use of coal world wide and protection of the climate

technology development to increase efficiency

high efficiency coal fired power plants

new advanced and reliable high temperature steels are needed

• World energy demand expands by

45% until 2030 (1,6% per year)

• Coal accounting for more than a

third of the overall rise

IEA, World Energy Outlook 2008 Reference case



4

Efficiency of Coal Fired Power Plants

- High efficiency Power Plants require high steam temperature and high pressure

Rotor shaft for HP and IP parts with suitable creep properties at operating temperature

- Strong development of creep resistant steels



5

Content

Introduction





Pilot turbine rotor



Manufacturing

Testing




6

Rotor materials for USC Power Plants

Boron-alloyed 10% Cr-steels

100,000 hrs rupture strength about 100 MPa

Resistance to corrosion

Resistance to thermo-mechanical cycling

Sufficient weldability

Creep rupture strength at 100.000h for new martensitic Cr-Steels

Abe, Kern and Viswanathan (Eds.). Creep-resistant steels, 2008

Addition of boron enables

to increase application

temperature by ca. 20°C



7

Rotor materials for USC Power Plants

Chemical composition of new Steels for high temperature rotor application



8

High Temperature Materials for Turbine Shafts

Materials used for high temperature rotors

30 CrMoNiV 5-11 HP/IP up to 565°C

23 CrMoNiWV 8-8 HP/IP/LP up to 565°C European

X12 CrMoWVNbN 10-1-1 HP/IP up to 610°C European COST E

X14 CrMoVNbN 10-1 HP/IP up to 600°C European COST F

TMK1 HP/IP up to 600°C Japanese similar Cost F

X13CrMoCoVNbNB 9 2 1 HP/IP up to 625°C European COST FB2

X18 CrMoVNbB 10 1 HP/IP up to 625°C European COST FB4

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Year

Application development of

COST E material for high

temperature rotors

(Saarschmiede)

Now launch of COST FB2 into regular production



9

Content

Introduction





Pilot turbine rotor



Manufacturing

Testing




10

COST FB2 Trial Shaft – Ingot Making

C Si Mn P S Cr Mo Ni V Al As Cu

X 12CrMoCoB 9 FB2 min. 0,12 0,05 0,30 9,00 1,40 0,10 0,18 0,005

SSF 1.4926.07 max. 0,14 0,10 0,40 0,010 0,005 9,50 1,60 0,20 0,22 0,010 0,012 0,10

ESU 1300, 56600kg 930726 0,135 0,076 0,31 0,0058 0,001 9,28 1,51 0,15 0,19 0,007 0,002 0,031

Chemical analysis

steel grade N B Co Nb Ti

0,015 0,0080 1,20 0,045

0,030 0,0100 1,40 0,065 0,005

0,026 0,0091 1,33 0,053 0,001

Developing of boron content in ESR ingot ESR-Ingot for manufacturing of the FB2 trial shaft



11

COST FB2 Trial rotor - Forging

ESR ingot: Ø 1300 mm / 57 t

Forging: Ø 1260 mm / 30 t

Forging Temperature: 1170 °C



12

Final shape of the rotor

0

10

20

30

40

50

60

70

80

90

100

600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300

Temperature [°C]

Red

of

Are

a [

%]

FT 7 270 ppm B

FB2 100ppm B

COST FB2 Trial Rotor

Forgeability of boron-alloyed Cr-steels

Limitation of boron content to

max. 100ppm



13

FB2 Trial rotor - Heat Treatment

PHT (preliminary heat treatment after forging)

- martensitic transformation

QHT (quality heat treatment)

- austenitizing 1100 °C/water spray

- 1st tempering 570 °C,

- 2nd tempering 700 °C



14

COST FB2 Trial rotor – UT inspection

FB2 trial rotor in machined condition after QHT



15

COST FB2 Trial rotor – mechanical properties

2100

815

T

A

B

C

D11086

ca. 300

410

1000

E F

ca. 200

1

21

5

1

05

0

D2

80

0

0.2 YS [MPa] RT

625°C

UTS [MPa] RT

625°C

EL [%] RT

625°C

RA [%] RT

625°C

Impact [J] RT 35, 27, 26 29 37, 36, 35 36 48, 42, 29 40 19, 28, 18 22 26, 18, 27 24 32, 23, 33 29 25, 21, 27, 22 24

FATT [°C]

67,470,584,7 83,8 82,1 82,5

25,3 26,7 26,0 28,7

473 464 463 464

D2 E

55,1

51

403 392 395 393 396

A B C D1 F

722

855

15,0

720

846

15,0

718

849

15,0

56,4

47

710

840

16,0

56,4

40

55,1

50

726

860

15,0

53,8

60

710

843

12,5

45,3

465

22,5

58 40

32,5

10,0

849

710

395

467

23,0



16

COST FB2 Trial rotor – microstructure

good through-hardenability for 1200mm

- 100% tempered martensite

- no dferrite detectable

- grain size (ASTM): 00 – 2



17

COST FB2 Creep rupture properties of trial rotors(Kern et al, 9th Liege Conference, 2010)

COST FB2 Trial rotor – creep properties



18

COST FB2 (X13CrMoCoVNbNB 9 2 1)

Production Parts (since 2007)

7 IP-turbine rotor parts ( 5 ESR Ingots, Ø 1300mm, 30mt – 56mt)

COST FB2 regular production parts

Part-

No.:

component Melt No. dimensions for

QHT [mm]

weigth for

QHT [kg]

delivery

weigth [kg]

1 IP turbine rotor part 930974 1100x2144 15936 9597









19

Mechanical Properties

and MDDS

COST FB2 regular production parts



20

Content

Introduction





Pilot turbine rotor



Manufacturing

Testing




21

0

50

100

150

200

500 550 600 650 700

Temperature [°C]

100.0

00 h

Cre

ep

Str

en

gth

[M

Pa]

Design

Criterion1%CrMoV

12%Cr MoV

X12CrMo(W)VNbN1011

X18CrMoVNbB9 1 Alloy 617

Alloy 625

K.H. Mayer: Werkstoffentwicklungen für Effizienzsteigerung von fossilen Kraftwerken, Düsseldorf, 2006

Comparison COST FB2 – FB4 (X18 CrMoVNbB 10 1)

- comparable creep properties, also significantly better creep strength than boron

free steels (COST E/F)

- similar chemical composition, but FB4 without cobalt more cost-effective

Type C Mn Cr Ni Mo V B N2 Nb W Co

FB2 0,13 0,35 9,3 0,10 1,50 0,20 0,0100 0,020 0,05 1,3

FB4 0,18 0,80 9,3 0,15 1,50 0,27 0,0100 0,015 0,06

COST FB 4 (X18 CrMoVNbB 10 1) – Chemical composition

COST FB4 Trial rotor



22


FB4 material very promising for high temperature turbine rotor

application

Problem: difficulties in manufacturing, because of insufficient UT-

Detectability (Minimum Detectable Defect Size - MDDS)

Several attempts without success

A new heat treatment have been applied to trial shaft of COST 536

program

solution: perlitic phase transformation for grain refinement

100 : 1 Pikrin-HCl-verdünnt 10´ 200 µm

30% Perlite



23

COST FB 4 trial rotor

- real production size forging (29,8 t)

- sectioning of the rotor after PHT

ESR Ingot: 1300mm, 45t weight


Chemical analysis

C Si Mn P S Cr Mo Ni V Al As Cu Sn Sb N B Co

X 18CrMoVNbB 10-1 1.4926.04 min. 0,17 0,05 0,20 9,00 1,40 0,10 0,24 0,005 0,010 0,0080

SSF FB4 max. 0,19 0,10 0,40 0,010 0,005 9,60 1,60 0,20 0,29 0,010 0,012 0,10 0,0040 0,0010 0,020 0,0100

ESR 1300 mm 0,18 0,09 0,28 0,005 0,001 9,21 1,50 0,17 0,03 0,007 0,003 0,03 0,0035 0,0006 0,016 0,0097 0,012

X 9CrMoCoB FB2 min. 0,12 0,30 9,00 1,45 0,10 0,18 0,015 0,0080 1,20

SSF max. 0,14 0,08 0,40 0,010 0,005 9,50 1,55 0,20 0,22 0,008 0,006 0,035 0,0040 0,001 0,030 0,0090 1,40

Melt No. 931005

steel grade W Nb

0,055

0,075

0,003 0,066

0,040

0,005 0,060



24

COST FB 4 Trial Rotor – Heat Treatment

Preliminary Heat Treatment

- martensitic transformation

perlitic transformation

Final QHT

MDDS (KSR) at core [mm - 2 MHz)

reading point 1 2 3 4 5

after PHT MDDS 2,0 6,3 5,3 5,3 2,7

after QHT* MDDS 12:00 2,1 5,7

04:00 1,9 6,0

08:00 2,1 5,3

MDDS (KSR) at core [mm - 2 MHz)

reading point 1 2 3 4 5

after PHT MDDS 2,0 6,3 5,3 5,3 2,7

after QHT* MDDS 12:00 2,1 5,7

04:00 1,9 6,0

08:00 2,1 5,3

sectioning

First QHT



25

UT results after grain refining and second quality heat treatment

reading point diameter

12:00 04:00 08:00 12:00 04:00 08:00 12:00 04:00 08:00

1.1 1205 1,1 1,1 1,1 0,7 0,9 0,8 0,9 0,8 0,8

1.2 1205 1,1 1,1 1,1 0,8 0,8 0,8 0,8 0,8 0,8

2.1 805 1,0 1,0 1,0 0,8 0,7 0,7 0,7 0,7 0,6

2.2 805 1,1 1,1 1,1 0,8 0,8 0,8 1,0 0,9 1,0

2.3 805 1,8 1,5 1,5

MDDS [mm]

2 MHz 4 MHz 5 MHz


MDDS significantly better than for FB2

MDDS values in the range of boron-free steels (COST E) can be achieved



26

T [°C]

0.2 YS [MPa] 20

625

UTS [MPa] 20

625

EL [%] 20

625

RA [%] 20

625

Impact [J] 20 25, 29, 20 25 54, 48, 38 47 34, 22, 32 29

FATT [°C]

microstructure 100% martensite 100% martensite 100% martensite

68 26

82,9 92

27,9 27,1

56,4 61,2 58,7

393 410

16,1 16,9 16,6

316 323

804 819 803

T1 A1 A2

658 659 657

COST FB4 Trial rotor - mechanical properties



27

99.9 : 1 RNO - Ätzmittel 200 µm

ASTM 3-6 ASTM 00 to -2

COST FB4 Trial rotor - microstructure

T1 surfaceA1 core



28

Content

Introduction





Pilot turbine rotor



Manufacturing

Testing




29


Long standing experience with 10 % Cr steel type Cost E with an reliable

production route - market share is increasing

Steel type Cost FB 2 is a successful development for steam

temperatures 620°C

Successful manufacturing and testing of FB2 Trial rotor

Introduction of FB2 into commercial application - several production parts

have been already manufactured

Type Cost FB 4 alloy is a promising candidate alloy and alternative to FB 2

Successful manufacturing and testing of FB4 Trial rotor

Perlitic Transformation improved MDDS considerably due to grain

refinement



30

Many thanks for

your attention!

The Saarschmiede GmbH Freiformschmiede is a company of the Saarstahl Group.

Work on COST FB4 sponsored by: Bundesministerium für Wirtschaft und

Technologie on the basis of a decision of the German Parliament

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