Prediction of creep life of X10CrMoVNbN-91 (P-91) steel through short term stress relaxation test methodology

Abstract

The methodology proposed here adopts short-term stress relaxation testing (SRT) to predict creep strength/life of X10CrMoVNbN 91 (P-91) steel. SRT has been performed at three temperatures (853, 873, 898 K), and at each temperature two prestrains (0.7 and 1.2%) were applied with a hold time of 7 h. The initial data, stress versus time, were converted to stress versus inelastic strain rate by computation and compared with conventional steady state creep rate. Creep life was predicted from the SRT results using the Monkman-Grant relationship, and compared with creep data. The comparison showed the predicted life to agree extremely well with the creep-rupture life (≈30 000 h). The calculated activation energy for SRT (719 kJ mol^-1) was found to be higher than the creep (415 kJ mol^-1). Detailed SEM and TEM studies revealed that the degradation of microstructure in terms of coarsening of M₂₃ C₆, and martensitic lath grains, had taken place and was commensurable to long term creep exposure.

Keywords

P-91 STEEL FERRITIC MARTENSITIC STEEL STRESS RELAXATION CREEP MICROSTRUCTURE

Get full access to this article

View all access options for this article.

References

KIMURA

, KUSHIMA

and ABE

: Proc. 5th Int. Conf. 011 ‘Advanced materials for 21st century turbines and power plants’, 3-7 July, (ed. Strang

et al.), 590-602; 2000, London, The Institute of Materials.

ASM metals handbook, 10th edn, Vol. 8, ‘Mechanical testing’, 364; 2000, Materials Park, OH, ASM International.

ALY

A. A.

, ABDEL-MALIK

T. G.

, ABDEEN

A. M.

and ELABAMY

H. M.

: Met. Sci Eng., 1984, 62, 181–185.

WOODFORD

D. A.

and IIJIMA

: in ‘Advances in turbine materials, design and manufacturing’, (ed. Strang

et al.), 613-624; 1997, London, The Institute of Materials.

ROHDE

R. W.

and SWEARENGEM

J. C.

: in ‘Stress relaxation testing’, (ed. Fox

), STP 676, 21-35; 1978, Philadelphia, PA, ASTM.

CANINICO

D. A.

: ‘Thick-walled pressure vessels for energy system. Technical programme and data package for use of modified 9Cr— 1Mo steel’, ASME Section land VIII, April 1982.

SIKKA

V. K.

, WARD

C. T.

and THOMAS

K. C.

: Proc. Conf. ‘Modified 9Cr — 1Mo steel’, October 1981, Warrendale, PA, 65–84.

KULVIR SINGH, S. C. BOSE and G. J. REDDY ‘Studies 011 creep rupture behaviour of weld joints of X10 CrMoNbN 91 and X20 CrMoV 12 1 steels’. Report no. RD: MTL: KS: 06:71, Corp. R&D, BHEL, 1999, India.

ANDERSON

, BELLGARDT

and JONES

F. L.

: Mater. Sci. Technol., 2003, 19, 207–213.

10.

ELLIS

F. V.

and SWINDEMAN

R. W.

: J. Press. Vess. Piping ASME, 1993, 262, 157–166.

11.

MONKMAN

F. C.

and GRANT

N. J.

: Proc. ASTM, 1956,56, 593–605.

12.

KUBON

, FOLDYNA

, HAJDUK

and SIMCEK

: ‘Parsons 2000: Advanced materials for 21st century turbines and power plant’, (ed. Strang

et al.), 485–497; 2000, London, IOM.

13.

KIMURA

, KUSHIMA

, ABE

, YAGI

and IRIE

: Proc. 4th Int. Charles Persons Turbine Conference’,(ed. Strang

et al.), 257–269; 1997, UK, IOM.

14.

WOODFORD

D. A.

: Mater. High Temp., 1997, 14, 413–420.

15.

BOSE

S. C.

, KULVIR SINGH and G. JAYARAMAN: J. Test. Eval., 2003, 31, (3), 183–195.

16.

ZAMARIK

S. Y.

and DAVIS

D. C.

: Trans. ASME, 1991, 113, 180 — 186.

17.

GHOSH

A. K.

: Acta Metall., 1980, 28, 1443–1465.

18.

STRANG

, FOLDYNA

, JACOBOVA

, KUBON

, VODAREK

and LENERT

: Proc. 4th Int. Charles Parsons Turbine Conf., (ed. Strang

et al.), 603–612; 1997, UK, IOM.

19.

LAFLEN

J. H.

and JASKE

C. E.

: ‘Stress relaxation testing’, (ed. Fox

), 182-205; 1978, ASTM STP 676.

20.

DALEO

J. A.

, ELLISON

K. A.

and WOODFORD

D. A.

: J. Eng. Gas Turbines Power, 1999, 121, 121–137.

21.

GOLDHOFF

R. M.

and GILL

R. F.

: Trans. ASME, Paper no. 71 WA/ Met-2, December 1971, pp. 1–6.

22.

WOODFORD

D. A.

: Accelerated high temperature performance evaluation for alloy optimization, embrittlement and life assessment. MPa Inc. Santabarbara, CA 93101. Private Communication. 2001.

23.

STRUDEL

J. L.

: in Proc. Int. Symp. on ‘Materials ageing and life management’, Vol. 2, (ed. Baldev

Raj

et al.), 649-656; 2000, New Delhi, Allied Publishers.

24.

GUO

J. T.

, YUAN

, YANG

H. C.

, LUPINC

and MALDINI

: Metall. Mater. Trans. A, 2001, 32A, 1103–1110.

25.

EVANS

R. W.

and WILSHIRE

: ‘Creep of metal and alloys’, 1985, London, The Institute of Metals.

26.

SPIGARELLI

, CERRI

, BIANCHI

and EVANGELISTA

: Mater. Sci Technol., 1999, 15, 1433— 1440.

27.

HORSEWELL

: Scand J. Metall., 1978, 7, 36–37.

28.

ASHBY

K. F.

: Surf Sci, 1972, 31, 498–542.