ASTM C1421 - 18

    Standard Test Methods for Determination of Fracture Toughness of Advanced Ceramics at Ambient Temperature

    Active Standard ASTM C1421 | Developed by Subcommittee: C28.01

    Book of Standards Volume: 15.01


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    Significance and Use

    5.1 Fracture toughness, KIc, is a measure of the resistance to crack extension in a brittle material. These test methods may be used for material development, material comparison, quality assessment, and characterization.

    5.2 The pb and the vb fracture toughness values provide information on the fracture resistance of advanced ceramics containing large sharp cracks, while the sc fracture toughness value provides this information for small cracks comparable in size to natural fracture sources. Cracks of different sizes may be used for the sc method. If the fracture toughness values vary as a function of the crack size it can be expected that KIsc will differ from KIpb and KIvb. Table 1 tabulates advantages, disadvantages, and applicability of each method.

    1. Scope

    1.1 These test methods cover the fracture toughness, KIc, determination of advanced ceramics at ambient temperature. The methods determine KIpb (precracked beam test specimen), KIsc (surface crack in flexure), and KIvb (chevron-notched beam test specimen). The fracture toughness values are determined using beam test specimens with a sharp crack. The crack is either a straight-through crack formed via bridge flexure (pb), or a semi-elliptical surface crack formed via Knoop indentation (sc), or it is formed and propagated in a chevron notch (vb), as shown in Fig. 1.

    1.6 Values expressed in these test methods are in accordance with the International System of Units (SI) and IEEE/ASTM SI 10.

    1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

    1.8 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

    1.9 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.


    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

    C1161 Test Method for Flexural Strength of Advanced Ceramics at Ambient Temperature

    C1322 Practice for Fractography and Characterization of Fracture Origins in Advanced Ceramics

    E4 Practices for Force Verification of Testing Machines

    E112 Test Methods for Determining Average Grain Size

    E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods

    E337 Test Method for Measuring Humidity with a Psychrometer (the Measurement of Wet- and Dry-Bulb Temperatures)

    E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

    E740/E740M Practice for Fracture Testing with Surface-Crack Tension Specimens

    E1823 Terminology Relating to Fatigue and Fracture Testing

    Reference Material

    NIST SRM 2100 Fracture Toughness of Ceramics Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.


    ICS Code

    ICS Number Code 81.060.30 (Advanced ceramics)

    UNSPSC Code

    UNSPSC Code


    Referencing This Standard
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    DOI: 10.1520/C1421-18

    Citation Format

    ASTM C1421-18, Standard Test Methods for Determination of Fracture Toughness of Advanced Ceramics at Ambient Temperature, ASTM International, West Conshohocken, PA, 2018, www.astm.org

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