ASTM C1678-09
Historical Standard: ASTM C1678-09 Standard Practice for Fractographic Analysis of Fracture Mirror Sizes in Ceramics and Glasses
SUPERSEDED (see Active link, below)
ASTM C1678
1. Scope
1.1 This practice pertains to the analysis and interpretation of fracture mirror sizes in brittle materials. Fracture mirrors (Fig. 1) are telltale fractographic markings that surround a fracture origin in brittle materials. The fracture mirror size may be used with known fracture mirror constants to estimate the stress in a fractured component. Alternatively, the fracture mirror size may be used in conjunction with known stresses in test specimens to calculate fracture mirror constants. The practice is applicable to glasses and polycrystalline ceramic laboratory test specimens as well as fractured components. The analysis and interpretation procedures for glasses and ceramics are similar, but they are not identical. Different optical microscopy examination techniques are listed and described, including observation angles, illumination methods, appropriate magnification, and measurement protocols. Guidance is given for calculating a fracture mirror constant and for interpreting the fracture mirror size and shape for both circular and noncircular mirrors including stress gradients, geometrical effects, and/or residual stresses. The practice provides figures and micrographs illustrating the different types of features commonly observed in and measurement techniques used for the fracture mirrors of glasses and polycrystalline ceramics.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Note The initial flaw may grow stably to size a c prior to unstable fracture when the stress intensity reaches K Ic . The mirror-mist radius is R i , the mist-hackle radius is R o , and the branching distance is R b . These transitions correspond to the mirror constants, A i , A o , and A b , respectively.
FIG. 1 Schematic of a Fracture Mirror Centered on a Surface Flaw of Initial Size (a).
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
ASTM Standards
C1145 Terminology of Advanced Ceramics
C1256 Practice for Interpreting Glass Fracture Surface Features
C1322 Practice for Fractography and Characterization of Fracture Origins in Advanced Ceramics
Keywords
ceramics; fractography; fracture mirror; fracture strength; fracture stress; fracture surface; glasses; hackle; microscope; mist; origin; residual stresses; Ceramicware; Fracture mirrors; Fracture testing--glass; Glassware;
ICS Code
ICS Number Code 81.060.20 (Ceramic products)
DOI: 10.1520/C1678-09
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