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Modelling of creep damage development in ferritic steels

Abstract

The physical creep damage, which is observed in fossil-fired power plants, is mainly due to the formation of cavities and their interaction. It has previously been demonstrated that both the nucleation and growth of creep cavities can be described by power functions in strain for low alloy and 12 % CrMoV creep resistant steels. It possible to show that the physical creep damage is proportional to the product of the number of cavities and their area. Hence, the physical creep damage can also be expressed in terms of the creep strain. In the presentation this physical creep damage is connected to the empirical creep damage classes (1-5). A creep strain-time function, which is known to be applicable to low alloy and 12 % CrMoV creep resistant steels, is used to describe tertiary creep. With this creep strain - time model the residual lifetime can be predicted from the observed damage. For a given damage class the remaining life is directly proportional to the service time. An expression for the time to the next inspection is proposed. This expression is a function of fraction of the total allowed damage, which is consumed till the next inspection. (orig.) 10 refs.
Authors:
Sandstroem, R [1] 
  1. Swedish Institute for Metals Research, Stockholm (Sweden)
Publication Date:
Dec 31, 1998
Product Type:
Conference
Report Number:
VTT-SYMP-185(v.2); CONF-980999-
Reference Number:
SCA: 360103; 200104; PA: FI-99:003084; EDB-99:036261; SN: 99002064698
Resource Relation:
Conference: 4. Baltica seminar on plant maintenance for managing life and performance, Helsinki (Finland), 7-9 Sep 1998; Other Information: PBD: 1998; Related Information: Is Part Of BALTICA IV. Plant maintenance for managing life and performance; Hietanen, S.; Auerkari, P. [eds.] [VTT Manufacturing Technology, Espoo (Finland). Operational Reliability]; PB: 398 p.
Subject:
36 MATERIALS SCIENCE; 20 FOSSIL-FUELED POWER PLANTS; FOSSIL-FUEL POWER PLANTS; CREEP; DAMAGE; CAVITATION; MATHEMATICAL MODELS; FERRITIC STEELS; SERVICE LIFE; TIME DEPENDENCE
OSTI ID:
325010
Research Organizations:
Technical Research Centre of Finland, Espoo (Finland)
Country of Origin:
Finland
Language:
English
Other Identifying Numbers:
Other: ON: DE99730863; ISBN 951-38-4577-X; TRN: FI9903084
Availability:
OSTI as DE99730863
Submitting Site:
FI
Size:
pp. 587-589
Announcement Date:
Apr 05, 1999

Citation Formats

Sandstroem, R. Modelling of creep damage development in ferritic steels. Finland: N. p., 1998. Web.
Sandstroem, R. Modelling of creep damage development in ferritic steels. Finland.
Sandstroem, R. 1998. "Modelling of creep damage development in ferritic steels." Finland.
@misc{etde_325010,
title = {Modelling of creep damage development in ferritic steels}
author = {Sandstroem, R}
abstractNote = {The physical creep damage, which is observed in fossil-fired power plants, is mainly due to the formation of cavities and their interaction. It has previously been demonstrated that both the nucleation and growth of creep cavities can be described by power functions in strain for low alloy and 12 % CrMoV creep resistant steels. It possible to show that the physical creep damage is proportional to the product of the number of cavities and their area. Hence, the physical creep damage can also be expressed in terms of the creep strain. In the presentation this physical creep damage is connected to the empirical creep damage classes (1-5). A creep strain-time function, which is known to be applicable to low alloy and 12 % CrMoV creep resistant steels, is used to describe tertiary creep. With this creep strain - time model the residual lifetime can be predicted from the observed damage. For a given damage class the remaining life is directly proportional to the service time. An expression for the time to the next inspection is proposed. This expression is a function of fraction of the total allowed damage, which is consumed till the next inspection. (orig.) 10 refs.}
place = {Finland}
year = {1998}
month = {Dec}
}