ASTM E1457-23
(Test Method)Standard Test Method for Measurement of Creep Crack Growth Times in Metals
Standard Test Method for Measurement of Creep Crack Growth Times in Metals
SIGNIFICANCE AND USE
6.1 Creep crack growth rate expressed as a function of the steady state C* or K characterizes the resistance of a material to crack growth under conditions of extensive creep deformation or under brittle creep conditions. Background information on the rationale for employing the fracture mechanics approach in the analyses of creep crack growth data is given in (11, 13, 30-35).
6.2 Aggressive environments at high temperatures can significantly affect the creep crack growth behavior. Attention must be given to the proper selection and control of temperature and environment in research studies and in generation of design data.
6.2.1 Expressing CCI time, t0.2 and CCG rate, da/dt as a function of an appropriate fracture mechanics related parameter generally provides results that are independent of specimen size and planar geometry for the same stress state at the crack tip for the range of geometries and sizes presented in this document (see Annex A1). Thus, the appropriate correlation will enable exchange and comparison of data obtained from a variety of specimen configurations and loading conditions. Moreover, this feature enables creep crack growth data to be utilized in the design and evaluation of engineering structures operated at elevated temperatures where creep deformation is a concern. The concept of similitude is assumed, implying that cracks of differing sizes subjected to the same nominal C*(t), Ct, or K will advance by equal increments of crack extension per unit time, provided the conditions for the validity for the specific crack growth rate relating parameter are met. See 11.7 for details.
6.2.2 The effects of crack tip constraint arising from variations in specimen size, geometry and material ductility can influence t0.2 and da/dt. For example, crack growth rates at the same value of C*(t), Ct in creep-ductile materials generally increases with increasing thickness. It is therefore necessary to keep the component dimensions in mind when selecti...
SCOPE
1.1 This test method covers the determination of creep crack initiation (CCI) and creep crack growth (CCG) in metals at elevated temperatures using pre-cracked specimens subjected to static or quasi-static loading conditions. The solutions presented in this test method are validated for base material (that is, homogenous properties) and mixed base/weld material with inhomogeneous microstructures and creep properties. The CCI time, t0.2, which is the time required to reach an initial crack extension of δai = 0.2 mm to occur from the onset of first applied force, and CCG rate, a˙ or da/dt are expressed in terms of the magnitude of creep crack growth correlated by fracture mechanics parameters, C* or K, with C* defined as the steady state determination of the crack tip stresses derived in principal from C*(t) and Ct (1-17).2 The crack growth derived in this manner is identified as a material property which can be used in modeling and life assessment methods (17-28).
1.1.1 The choice of the crack growth correlating parameter C*, C*(t), Ct, or K depends on the material creep properties, geometry and size of the specimen. Two types of material behavior are generally observed during creep crack growth tests; creep-ductile (1-17) and creep-brittle (29-44). In creep ductile materials, where creep strains dominate and creep crack growth is accompanied by substantial time-dependent creep strains at the crack tip, the crack growth rate is correlated by the steady state definitions of Ct or C*(t) , defined as C* (see 1.1.4). In creep-brittle materials, creep crack growth occurs at low creep ductility. Consequently, the time-dependent creep strains are comparable to or dominated by accompanying elastic strains local to the crack tip. Under such steady state creep-brittle conditions, Ct or K could be chosen as the correlating parameter (8-14).
1.1.2 In any one test, two regions of crack growth behavior may be present (12, 13)....
General Information
Relations
Buy Standard
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1457 − 23
Standard Test Method for
1
Measurement of Creep Crack Growth Times in Metals
This standard is issued under the fixed designation E1457; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Steady-state creep crack growth rate behavior is covered by
this standard. In addition, specific recommendations are made
1.1 This test method covers the determination of creep crack
in 11.7 as to how the transient region should be treated in terms
initiation (CCI) and creep crack growth (CCG) in metals at
of an initial crack growth period. During steady state, a unique
elevated temperatures using pre-cracked specimens subjected
correlation exists between da/dt and the appropriate crack
to static or quasi-static loading conditions. The solutions
growth rate relating parameter.
presented in this test method are validated for base material
1.1.3 In creep ductile materials, extensive creep occurs
(that is, homogenous properties) and mixed base/weld material
when the entire un-cracked ligament undergoes creep defor-
with inhomogeneous microstructures and creep properties. The
mation. Such conditions are distinct from the conditions of
CCI time, t , which is the time required to reach an initial
0.2
small-scale creep and transition creep (1-10). In the case of
crack extension of δa = 0.2 mm to occur from the onset of first
i
extensive creep, the region dominated by creep deformation is
applied force, and CCG rate, a˙ or da/dt are expressed in terms
significant in size in comparison to both the crack length and
of the magnitude of creep crack growth correlated by fracture
the uncracked ligament sizes. In small-scale-creep only a small
mechanics parameters, C* or K, with C* defined as the steady
region of the un-cracked ligament local to the crack tip
state determination of the crack tip stresses derived in principal
2
experiences creep deformation.
from C*(t) and C (1-17). The crack growth derived in this
t
1.1.4 The creep crack growth rate in the extensive creep
manner is identified as a material property which can be used
region is correlated by the C*(t)-integral. The C parameter
in modeling and life assessment methods (17-28). t
correlates the creep crack growth rate in the small-scale creep
1.1.1 The choice of the crack growth correlating parameter
and the transition creep regions and reduces, by definition, to
C*, C*(t), C , or K depends on the material creep properties,
t
C*(t) in the extensive creep region (5). Hence in this document
geometry and size of the specimen. Two types of material
the definition C* is used as the relevant parameter in the steady
behavior are generally observed during creep crack growth
state extensive creep regime whereas C*(t) and/or C are the
tests; creep-ductile (1-17) and creep-brittle (29-44). In creep t
parameters which describe the instantaneous stress state from
ductile materials, where creep strains dominate and creep crack
the small scale creep, transient and the steady state regimes in
growth is accompanied by substantial time-dependent creep
creep. The recommended functions to derive C* for the
strains at the crack tip, the crack growth rate is correlated by
different geometries shown in Annex A1 is described in Annex
the steady state definitions of C or C*(t), defined as C* (see
t
A2.
1.1.4). In creep-brittle materials, creep crack growth occurs at
1.1.5 An engineering definition of an initial crack extension
low creep ductility. Consequently, the time-dependent creep
size δa is used in order to quantify the initial period of crack
strains are comparable to or dominated by accompanying
i
development. This distance is given as 0.2 mm. It has been
elastic strains local to the crack tip. Under such steady state
shown (41-44) that this initial period which exists at the start of
creep-brittle conditions, C or K could be chosen as the
t
the test could be a substantial period of the test time. During
correlating parameter (8-14).
this early period the crack tip undergoes damage development
1.1.2 In any one test, two regions of crack growth behavior
as well as redistribution of stresses prior reaching steady state.
may be present (12, 13). The initial transient region where
Recommendation is made to correlate this initial crack growth
elastic strains dominate and creep damage develops and in the
period defined as t at δa = 0.2 mm with the steady state C*
steady state region where crack grows proportionally to
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: E1457 − 19 E1457 − 23
Standard Test Method for
1
Measurement of Creep Crack Growth Times in Metals
This standard is issued under the fixed designation E1457; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1
ε NOTE—Section 4.2.1.1 was editorially corrected in July 2020.
1. Scope
1.1 This test method covers the determination of creep crack initiation (CCI) and creep crack growth (CCG) in metals at elevated
temperatures using pre-cracked specimens subjected to static or quasi-static loading conditions. The solutions presented in this test
method are validated for base material (i.e. (that is, homogenous properties) and mixed base/weld material with inhomogeneous
microstructures and creep properties. The CCI time, t , which is the time required to reach an initial crack extension of δa = 0.2
0.2 i
mm to occur from the onset of first applied force, and CCG rate, a˙ or da/dt are expressed in terms of the magnitude of creep crack
growth correlated by fracture mechanics parameters, C* or K, with C* defined as the steady state determination of the crack tip
2
stresses derived in principal from C*(t) and C (1-17). The crack growth derived in this manner is identified as a material property
t
which can be used in modeling and life assessment methods (17-28).
1.1.1 The choice of the crack growth correlating parameter C*, C*(t),C , or K depends on the material creep properties, geometry
t
and size of the specimen. Two types of material behavior are generally observed during creep crack growth tests; creep-ductile
(1-17) and creep-brittle (29-44). In creep ductile materials, where creep strains dominate and creep crack growth is accompanied
by substantial time-dependent creep strains at the crack tip, the crack growth rate is correlated by the steady state definitions of
C or C*(t), defined as C* (see 1.1.4). In creep-brittle materials, creep crack growth occurs at low creep ductility. Consequently,
t
the time-dependent creep strains are comparable to or dominated by accompanying elastic strains local to the crack tip. Under such
steady state creep-brittle conditions, C or K could be chosen as the correlating parameter (8-14).
t
1.1.2 In any one test, two regions of crack growth behavior may be present (12, 13). The initial transient region where elastic
strains dominate and creep damage develops and in the steady state region where crack grows proportionally to time. Steady-state
creep crack growth rate behavior is covered by this standard. In addition, specific recommendations are made in 11.7 as to how
the transient region should be treated in terms of an initial crack growth period. During steady state, a unique correlation exists
between da/dt and the appropriate crack growth rate relating parameter.
1.1.3 In creep ductile materials, extensive creep occurs when the entire un-cracked ligament undergoes creep deformation. Such
conditions are distinct from the conditions of small-scale creep and transition creep (1-10). In the case of extensive creep, the
region dominated by creep deformation is significant in size in comparison to both the crack length and the uncracked ligament
sizes. In small-scale-creep only a small region of the un-cracked ligament local to the crack tip experiences creep deformation.
1.1.4 The creep crack growth rate in the extensive creep region is correlated by the C*(t)-integral. The C parameter correlates the
t
creep crack growth rate in the small-scale creep and the transition creep regions and reduces, by definition, to C*(t) in the extensive
creep region (5). Hence in this document the definition C* is used as the relevant parameter in the steady state extensive creep
1
This test method is under the jurisdiction of ASTM Committee E08 on Fatigue and Fracture and is the direct responsibility of Subcommittee E08.06 on Crack Growth
Behavior.
Current edition approved Nov. 15, 2019Nov. 15, 2023. Published February 2020December 2023. Originally approved in 1992. Last previous edition approved in 20152019
ɛ1
as E1457 – 15.E1457 – 19 . DOI: 10.1520/E1457-19E01.10.1520/E1457-23.
2
The boldface numbers in parentheses refer to the list of references at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
--------------
...
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E1457 − 23
Standard Test Method for
1
Measurement of Creep Crack Growth Times in Metals
This standard is issued under the fixed designation E1457; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Steady-state creep crack growth rate behavior is covered by
this standard. In addition, specific recommendations are made
1.1 This test method covers the determination of creep crack
in 11.7 as to how the transient region should be treated in terms
initiation (CCI) and creep crack growth (CCG) in metals at
of an initial crack growth period. During steady state, a unique
elevated temperatures using pre-cracked specimens subjected
correlation exists between da/dt and the appropriate crack
to static or quasi-static loading conditions. The solutions
growth rate relating parameter.
presented in this test method are validated for base material
1.1.3 In creep ductile materials, extensive creep occurs
(that is, homogenous properties) and mixed base/weld material
when the entire un-cracked ligament undergoes creep defor-
with inhomogeneous microstructures and creep properties. The
mation. Such conditions are distinct from the conditions of
CCI time, t , which is the time required to reach an initial
0.2
small-scale creep and transition creep (1-10). In the case of
crack extension of δa = 0.2 mm to occur from the onset of first
i
extensive creep, the region dominated by creep deformation is
applied force, and CCG rate, a˙ or da/dt are expressed in terms
significant in size in comparison to both the crack length and
of the magnitude of creep crack growth correlated by fracture
the uncracked ligament sizes. In small-scale-creep only a small
mechanics parameters, C* or K, with C* defined as the steady
region of the un-cracked ligament local to the crack tip
state determination of the crack tip stresses derived in principal
2
experiences creep deformation.
from C*(t) and C (1-17). The crack growth derived in this
t
1.1.4 The creep crack growth rate in the extensive creep
manner is identified as a material property which can be used
region is correlated by the C*(t)-integral. The C parameter
in modeling and life assessment methods (17-28). t
correlates the creep crack growth rate in the small-scale creep
1.1.1 The choice of the crack growth correlating parameter
and the transition creep regions and reduces, by definition, to
C*, C*(t), C , or K depends on the material creep properties,
t
C*(t) in the extensive creep region (5). Hence in this document
geometry and size of the specimen. Two types of material
the definition C* is used as the relevant parameter in the steady
behavior are generally observed during creep crack growth
state extensive creep regime whereas C*(t) and/or C are the
tests; creep-ductile (1-17) and creep-brittle (29-44). In creep
t
parameters which describe the instantaneous stress state from
ductile materials, where creep strains dominate and creep crack
the small scale creep, transient and the steady state regimes in
growth is accompanied by substantial time-dependent creep
creep. The recommended functions to derive C* for the
strains at the crack tip, the crack growth rate is correlated by
different geometries shown in Annex A1 is described in Annex
the steady state definitions of C or C*(t), defined as C* (see
t
A2.
1.1.4). In creep-brittle materials, creep crack growth occurs at
1.1.5 An engineering definition of an initial crack extension
low creep ductility. Consequently, the time-dependent creep
size δa is used in order to quantify the initial period of crack
strains are comparable to or dominated by accompanying
i
development. This distance is given as 0.2 mm. It has been
elastic strains local to the crack tip. Under such steady state
shown (41-44) that this initial period which exists at the start of
creep-brittle conditions, C or K could be chosen as the
t
the test could be a substantial period of the test time. During
correlating parameter (8-14).
this early period the crack tip undergoes damage development
1.1.2 In any one test, two regions of crack growth behavior
as well as redistribution of stresses prior reaching steady state.
may be present (12, 13). The initial transient region where
Recommendation is made to correlate this initial crack growth
elastic strains dominate and creep damage develops and in the
period defined as t at δa = 0.2 mm with the steady state C*
steady state region where crack grows proportionally to time.
0.2 i
when the crack tip is under extensive creep and with K for
creep brittle conditions. The values for C* and K should be
1
This test
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.