ASTM C1256-93(2019)
(Practice)Standard Practice for Interpreting Glass Fracture Surface Features
Standard Practice for Interpreting Glass Fracture Surface Features
SIGNIFICANCE AND USE
5.1 Fractography is often used to help identify the events that have resulted in the fracture of a glass object. This practice defines the appearance of various fracture surface features, as well as their method of formation. Thus, there can be a common understanding of their relationship to the fracture process as well as a common terminology.
SCOPE
1.1 Fracture features on the surface of a crack reflect the nature and course of the fracture event associated with the breakage of a glass object. This practice is a guide to the identification and interpretation of these fracture surface features.
1.2 The practice describes the various fracture surface features as to their appearance, the process of formation and their significance.
1.3 The practice does not provide the procedural information necessary for a complete fractographic analysis. Such information is available in the general literature. (See Glossary for suggested literature).
1.4 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.
General Information
Relations
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: C1256 − 93 (Reapproved 2019)
Standard Practice for
1
Interpreting Glass Fracture Surface Features
This standard is issued under the fixed designation C1256; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.3 forking angle—the angle subtended by two immedi-
ately adjacent fractures which have just branched or forked.
1.1 Fracture features on the surface of a crack reflect the
3.1.4 fracture mirror constant—a constant, characteristic of
nature and course of the fracture event associated with the
a given glass composition, which, when divided by the square
breakage of a glass object. This practice is a guide to the
root of the fracture mirror radius, will yield the fracture stress.
identification and interpretation of these fracture surface fea-
tures.
3.1.5 fracture mirror radius—a dimension of the fracture
mirror as measured along the original specimen surface. It is
1.2 The practice describes the various fracture surface
defined as the distance from the origin to the first detectable
features as to their appearance, the process of formation and
mist.
their significance.
3.1.6 fracture surface markings—features of the fracture
1.3 The practice does not provide the procedural informa-
surface produced during the fracture event which are useful in
tion necessary for a complete fractographic analysis. Such
determining the origin and the nature of the local stresses that
information is available in the general literature. (See Glossary
produced the fracture.
for suggested literature).
3.1.7 fracture system—the fracture surfaces that have a
1.4 This international standard was developed in accor-
common cause or origin.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the 3.1.8 terminal velocity—the uppermost limiting velocity at
Development of International Standards, Guides and Recom- which a crack can propagate in a material, the approach to
mendations issued by the World Trade Organization Technical which is marked on the fracture generated surface by the
Barriers to Trade (TBT) Committee. presence of mist. The terminal velocity is approximately one
half the velocity of sound in the material.
2. Referenced Documents
3.1.9 uniform stress—a state of stress that does not change
2
2.1 ASTM Standards: within the region of concern.
C162Terminology of Glass and Glass Products
4. Summary
3. Terminology
4.1 This practice is intended to aid in the identification of
fracturesurfacemarkingsaswellastoassistintheunderstand-
3.1 Definitions:
ing of their formation and significance.
3.1.1 bending stress—a continuously and linearly changing
stress across the thickness of a glass body, varying from
5. Significance and Use
compression on one surface to tension on the opposite surface.
5.1 Fractography is often used to help identify the events
3.1.2 forking—amechanismwherebyapropagatingfracture
thathaveresultedinthefractureofaglassobject.Thispractice
branches into two fractures, separated from each other by an
defines the appearance of various fracture surface features, as
acute angle.
well as their method of formation. Thus, there can be a
common understanding of their relationship to the fracture
1 process as well as a common terminology.
ThispracticeisunderthejurisdictionofASTMCommitteeC14GlassandGlass
Products and is the direct responsibility of Subcommittee C14.04 on Physical and
Mechanical Properties
6. Fracture Surface Markings
Current edition approved Aug. 1, 2019. Published August 2019. Originally
6.1 Origin:
approved in 1993. Last previous edition approved in 2013 as C1256–93 (2013)
DOI: 10.1520/C1256-93R19.
6.1.1 Identification—The origin is almost always found at
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
the junction where the fracture-generated surface meets a free
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
surface or a dissimilar material. Commonly, the origin is
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. symmetrically located near the apex of the mirror and it is
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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C1256 − 93 (2019)
usually small compared to the mirror. Fig. 1 shows typical
origins and mirrors bounded by mist.
6.1.2 Format
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