ASTM E1820-2018a Standard Test Method for Measurement of Fracture Toughness.pdf
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1、Designation: E1820 18E1820 18aStandard Test Method forMeasurement of Fracture Toughness1This standard is issued under the fixed designation E1820; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers procedures and guidelines for the determination of fracture toughness of metallic materials usingthe following paramet
3、ers: K, J, and CTOD (). Toughness can be measured in the R-curve format or as a point value. The fracturetoughness determined in accordance with this test method is for the opening mode (Mode I) of loading.NOTE 1Until this version, KIc could be evaluated using this test method as well as by using Te
4、st Method E399. To avoid duplication, the evaluationof KIc has been removed from this test method and the user is referred to Test Method E399.1.2 The recommended specimens are single-edge bend, SE(B), compact, C(T), and disk-shaped compact, DC(T). Allspecimens contain notches that are sharpened wit
5、h fatigue cracks.1.2.1 Specimen dimensional (size) requirements vary according to the fracture toughness analysis applied. The guidelines areestablished through consideration of material toughness, material flow strength, and the individual qualification requirements ofthe toughness value per values
6、 sought.NOTE 2Other standard methods for the determination of fracture toughness using the parameters K, J, and CTOD are contained inTest Methods E399,E1290, and E1921. This test method was developed to provide a common method for determining all applicable toughness parameters from a single test.1.
7、3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish ap
8、propriate safety, health, and environmental practices and determine the applicability ofregulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Devel
9、opment of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE8/E8M Test Methods for Tension Testing of Metallic Materi
10、alsE21 Test Methods for Elevated Temperature Tension Tests of Metallic MaterialsE23 Test Methods for Notched Bar Impact Testing of Metallic MaterialsE399 Test Method for Linear-Elastic Plane-Strain Fracture Toughness KIc of Metallic MaterialsE1290 Test Method for Crack-Tip Opening Displacement (CTOD
11、) Fracture Toughness Measurement (Withdrawn 2013)3E1823 Terminology Relating to Fatigue and Fracture TestingE1921 Test Method for Determination of Reference Temperature, To, for Ferritic Steels in the Transition RangeE1942 Guide for Evaluating Data Acquisition Systems Used in Cyclic Fatigue and Frac
12、ture Mechanics TestingE2298 Test Method for Instrumented Impact Testing of Metallic Materials2.2 ASTM Data Set:4E1820/1DS1(2015) Standard data set to evaluate computer algorithms for evaluation of JIc using, Annex A9 of E18201 This test method is under the jurisdiction of ASTM Committee E08 on Fatig
13、ue and Fracture and is the direct responsibility of Subcommittee E08.07 on FractureMechanics.Current edition approved May 1, 2018Nov. 1, 2018. Published July 2018February 2019. Originally approved in 1996. Last previous edition approved in 20172018 asE1820 17a.E1820 18. DOI: 10.1520/E1820-1810.1520/
14、E1820-18A2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical stand
15、ard is referenced on www.astm.org.4 This data set is available for download from ASTM at https:/www.astm.org/COMMITTEE/E08.htm, under the heading, Additional Information.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes h
16、ave been made to the previous version. Becauseit 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 versionof the standard as published by ASTM is to be considered the official d
17、ocument.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Terminology E1823 is applicable to this test method. Only items that are exclusive to Test Method E1820, or that havespecific discussion items associated, are l
18、isted in this section.3.2 Definitions of Terms Specific to This Standard:3.2.1 compliance LF1, nthe ratio of displacement increment to force increment.3.2.2 crack opening displacement (COD) L, nforce-induced separation vector between two points at a specific gage length.The direction of the vector i
19、s normal to the crack plane.3.2.2.1 DiscussionIn this practice, displacement, v, is the total displacement measured by clip gages or other devices spanning the crack faces.3.2.3 crack extension, a L, nan increase in crack size.3.2.4 crack-extension force, G FL1 or FLL2, nthe elastic energy per unit
20、of new separation area that is made availableat the front of an ideal crack in an elastic solid during a virtual increment of forward crack extension.3.2.5 crack-tip opening displacement (CTOD), L, ncrack displacement resulting from the total deformation (elastic plusplastic) at variously defined lo
21、cations near the original (prior to force application) crack tip.3.2.5.1 DiscussionIn this test method, CTOD is the displacement of the crack surfaces normal to the original (unloaded) crack plane at the tip of thefatigue precrack, ao. In this test method, CTOD is calculated at the original crack si
22、ze, ao, from measurements made from the forceversus displacement record.3.2.5.2 DiscussionIn CTOD testing, Ic L is a value of CTOD near the onset of slow stable crack extension, here defined as occurring at ap = 0.2mm (0.008 in.) + 0.7Ic.3.2.5.3 DiscussionIn CTOD testing, c L is the value of CTOD at
23、 the onset of unstable crack extension (see 3.2.36) or pop-in (see 3.2.22) whenap 0.2 mm (0.008 in.) + 0.7u. The u corresponds to the force Pu and the clip gage displacement vu (seeFig. 1). It may be size-dependent and a function of test specimen geometry. It can be useful to define limits on ductil
24、e fracturebehavior.3.2.5.5 DiscussionIn CTOD testing, c* L characterizes the CTOD fracture toughness of materials at fracture instability prior to the onset ofsignificant stable tearing crack extension. The value of c* determined by this test method represents a measure of fracturetoughness at insta
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