ASTM E812-91(1997)

Standard Test Method for Crack Strength of Slow-Bend Precracked Charpy Specimens of High-Strength Metallic Materials (Withdrawn 2005)

SCOPE
1.1 This test method covers the determination of the crack strength [sigma]c of a Charpy-type specimen (see Fig. 1) containing a fatigue crack tested in slow bending. The nominal cross-sectional dimensions of this specimen are identical to those given in Test Methods E23 (Fig. 4A) for the standard Charpy test specimen. The crack strength will be sensitive to changes in the plane-strain fracture toughness providing the strength of the specimen is determined primarily by crack propagation and not by plastic instability.
WITHDRAWN RATIONALE
This test method covers the determination of the crack strength c  of a Charpy-type specimen (see Fig. 1) containing a fatigue crack tested in slow bending. The nominal cross-sectional dimensions of this specimen are identical to those given in Test Methods E 23 (Fig. 4A) for the standard Charpy test specimen.
Formerly under the jurisdiction of Committee E08 on Fracture Testing, this test method was withdrawn in May 2005 in accordance with section 10.5.3.1 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date

General Information

• Status: Withdrawn
• Publication Date: 09-Jun-1997
• Withdrawal Date: 18-May-2005
• ICS: 77.040.10 - Mechanical testing of metals
• Technical Committee: E08 - Fatigue and Fracture
• Drafting Committee: E08.02 - Terminology

Relations

• Referred By: ASTM F1624-12(2018) - Standard Test Method for Measurement of Hydrogen Embrittlement Threshold in Steel by the Incremental Step Loading Technique
• Effective Date: 10-Jun-1997

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:E812–91(Reapproved 1997)
Standard Test Method for
Crack Strength of Slow-Bend Precracked Charpy Specimens
of High-Strength Metallic Materials
This standard is issued under the fixed designation E812; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 3.1.1.2 Discussion—Crack strength is calculated on the
basisofthemaximumloadandtheoriginalcross-sectionalarea
1.1 This test method covers the determination of the crack
(net cross-section or ligament). Thus, it takes into account the
strength s of a Charpy-type specimen (see Fig. 1) containing
c
original size of the crack but ignores any crack extension that
a fatigue crack tested in slow bending. The nominal cross-
may occur during the test.
sectional dimensions of this specimen are identical to those
3.1.1.3 Discussion—Crack strength is analogous to the
given in Test Methods E23 (Fig. 4A) for the standard Charpy
ultimate tensile strength, as it is based on the ratio of the
test specimen. The crack strength will be sensitive to changes
maximum load to the minimum cross-sectional area of the
in the plane-strain fracture toughness providing the strength of
specimen at the start of the test.
thespecimenisdeterminedprimarilybycrackpropagationand
not by plastic instability.
4. Summary of Test Method
1.2 This standard does not purport to address all of the
4.1 This test method employs a Charpy specimen provided
safety concerns, if any, associated with its use. It is the
with a sharp notch terminating in a fatigue crack tested in
responsibility of the user of this standard to establish appro-
three-point bending using fixtures that minimize the contribu-
priate safety and health practices and determine the applica-
tion of friction forces to the measured applied load. The
bility of regulatory limitations prior to use.
maximum load in the test is recorded and the crack strength is
2. Referenced Documents determined from this value and the original dimensions of the
specimen using the simple-beam equation.
2.1 ASTM Standards:
E4 Practices for Force Verification of Testing Machines
5. Significance and Use
E8 TestMethodsforTensionTestingofMetallicMaterials
5.1 The crack strength does not provide a quantitative
E23 Test Methods for Notched Bar Impact Testing of
2 measure of fracture resistance that could be used in the design
Metallic Materials
of structures. However, experience with a number of high-
E139 Practice for Conducting Creep, Creep-Rupture, and
2 strength alloys has shown that the ratio of the crack strength
Stress-Rupture Tests of Metallic Materials
to the 0.2% tensile yield strength s /s or to the tensile
c YS
E399 Test Method for Plane-Strain Fracture Toughness of
2 ultimate strength, s /s , can be correlated with K /s or
c UT I c YS
Metallic Materials
3 with K /s , respectively, where K is the plane-strain
I c UT I c
E616 Terminology Relating to Fracture Testing
4, 5
fracture toughness in accordance with Test Method E399 .
3. Terminology The lower-strength limits of useful correlations established by
the presently available data are: for steel s =1378 MPa
YS
3.1 Definition:
(200ksi),foraluminumalloys s =275.6MPa(40ksi),and
YS
3.1.1 crack strength, s [FL ]—the maximum value of the
c
for titanium alloys s =826 MPa (120 ksi). Correlations of
YS
nominal (net-section) stress that a cracked specimen is capable
this type can be useful for the following purposes:
of sustaining.
5.1.1 In research and development of materials, to study the
3.1.1.1 Discussion—See definition of nominal stress in
effects of such variables as composition, heat treatment,
Terminology E616.
ThistestmethodisunderthejurisdictionofASTMCommitteeE-8onFracture
Testing and is the direct responsibility of Subcommittee E08.02 on Standards and Succop, G., and Brown, W. F., Jr., “Estimation of K from Slow Bend
I c
Terminology. Precracked Charpy Specimen Strength Ratios,” Developments in Fracture Mechan-
Current edition approved Sept. 15, 1991. Published November 1991. Originally ics Test Method Standardization, ASTM-STP 632, 1977.
published as E812–81. Last previous edition E812–81(1986). “Rapid Inexpensive Tests for Determining Fracture Toughness,” National
Annual Book of ASTM Standards, Vol 03.01. Materials Advisory Board, National Academy of Sciences, NMAB 328, Washing-
Discontinued 1996; see 1995 Annual Book of ASTM Standards, Vol 03.01. ton, DC, 1976.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E812–91 (1997)
NOTE 1—All dimensions are in millimetres.
NOTE 2—A surfaces shall be perpendicular or parallel as applicable to within 0.025 mm TIR.
NOTE 3—Crack starter shall be perpendicular to specimen length and thickness to within 62°.
FIG. 1 Dimensions of Precracked Charpy Specimen
mechanical processing, etc., where a ranking of materials in
6. Apparatus
terms of their plane-strain fracture toughness K may be
I c
6.1 Tension-Testing Machine, conforming to the require-
useful.
ments of Practices E4.
5.1.2 For specifications of acceptance and manufacturing
6.2 Bend-Test Fixture—The procedure involves testing of
quality control and for service evaluation to compare the
the specimen in three-point bending. The bend test fixture
resistance to plane-strain fracture of a number of materials that
should provide support rollers that are free to rotate and move
are otherwise suitable for an application; provided that a
apartslightlyduringloading(forexample,seetheTestMethod
“calibration relation” can be established between s and K
c I c
E399 bend test fixture for general principles of design). The
over a range of toughness of interest.
nominal span between support rollers shall be 40 mm (1.57
5.1.3 The variation of crack strength with testing tempera-
in.). If the diameter of the support rollers is between 7.5 mm
ture may be useful in establishing transition temperatures.
(0.30 in.) and 10 mm (0.39 in.) there will be negligible change
5.2 When using the crack strength of any of the preceding
in span during deformation of the specimen.
purposes, it is important that certain precautions be kept in
6.3 Temperature Control and Measurement—For tests at
mind.
temperatures other than ambient, any suitable means may be
5.2.1 The sensitivity of the crack strength to changes in the
used to cool or heat the specimen providing the region
plane-strain fracture toughness will decrease as the toughness
including the notched and cracked section can be maintained
approaches a value sufficient to cause the crack strength to be
within 62°C (63.6°F) of the desired temperature during the
determined by the plastic limit load.Available data obtained at
course of the test.
room temperature for various materials indicate that useful
6.3.1 Temperatures shall be measured with calibrated ther-
sensitivityof s /s tochangesin K /s ismaintainedup
c YS I c YS
mocouples used in conjunction with potentiometers or milli-
to values of s /s of about 2.0. On the average, for
c YS
voltmeters. Such measurements are subject to various errors
high-strengthmetallicmaterials,thislimitationwillcorrespond
particularly at elevated temperatures and reference should be
½ ½
to a value of K /s of approximately 0.12 m (0.6 in. ).
I c YS
made to Practice E139 for a discussion of errors encountered
5.2.2 There is no assurance that a calibration relation
in elevated temperature testing.
established for one class of materials will be equally useful for
6.3.2 The temperature-measuring apparatus should be cali-
another class of materials or that changes in the processing of
brated periodically against standards traceable to the National
a given material will not alter the calibration relation. There-
Bureau of Standards in order to ensure the accuracy specified
fore, when it is desired to closely estimate K from such a
I c
in 6.3 can be achieved.
relation, this relation should be carefully established over the
6.3.3 The temperature of the specimen during any test other
range of plane-strain fracture toughness of interest for a
than one at room temperature shall be measured by means of a
particular alloy condition.
thermocouple attached near the notched and cracked section.
5.2.3 Calibration relations should not be extrapolated.
This thermocouple may be spot welded in place, however, the
5.2.4 The crack strength of some materials will be sensitive
spot weld location should avoid the crack path. Requirements
to the rate of loading and loading rates should be confined to
for cooling or heating the specimens prior to testing are
the range given in 8.3.2.
discussed in Test Methods E23 and should be followed in this
5.2.5 The crack strength will be influenced by the testing method. In the case where the specimen and the test fixture is
temperature and calibration relations may change with testing immersed in a liquefied gas maintained at its boiling point, no
temperature. temperature measurement is required provided experience
E812–91 (1997)
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