ASTM E3039-2018 Standard Test Method for Determination of Crack-Tip-Opening Angle of Pipe Steels Using DWTT-Type Specimens.pdf

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1、Designation: E3039 16E3039 18Standard Test Method forDetermination of Crack-Tip-Opening Angle of Pipe SteelsUsing DWTTDWTT-Type Specimens1This standard is issued under the fixed designation E3039; the number immediately following the designation indicates the year oforiginal adoption or, in the case

2、 of revision, the year of last revision. A number 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 the determination of fracture propagation toughness in terms of the

3、steady-state crack-tip-openingangle (CTOA) using the drop-weight tear test (DWTT)(DWTT)-type specimen. The method is applicable to pipe steels that exhibitpredominantly ductile fracture with at least 85% shear area measured according to Test Method E436 - Standard Test Method forDrop-Weight Tear Tes

4、ts of Ferritic Steels. This test method applies to steel pipes with wall thicknesses between 6 mm and 20 mm.Annex A1 describes the method to test pipe steels with wall thickness between 20 mm to 32 mm.1.2 In terms of apparatus, specimen design, and test methodology, this test method draws from Test

5、Method E436 andAPI 5L3- Recommended Practice for Conducting Drop-Weight Tear Tests on Line Pipe.1.3 The development of this test method has been driven by the need to design for fast ductile fracture arrest of axial runningcracks in steel high-pressure gas pipelines (1).2The purpose has been to deve

6、lop a test to characterize fracture propagationresistance in a form suitable for use as a pipe mill test (2). The traditional Charpy test has been shown to be inadequate for modernhigh toughness pipe steels (1). This test method measures fracture propagation resistance in terms of crack-tip opening

7、angle, andis used to characterize pipe steels.1.4 The values stated in SI units are to be regarded as the standard values; those given in parentheses are for informationonly.standard. No other units of measurement are included in this standard.1.5 This standard does not purport to address all of the

8、 safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.6 This international standard was develope

9、d in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2

10、.1 ASTM Standards:3E177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE436 Test Method for Drop-Weight Tear Tests of Ferritic SteelsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodE1823 Terminology Relating to Fatigue and Fractu

11、re TestingE1942 Guide for Evaluating Data Acquisition Systems Used in Cyclic Fatigue and Fracture Mechanics TestingE2298 Test Method for Instrumented Impact Testing of Metallic MaterialsE2472 Test Method for Determination of Resistance to Stable Crack Extension under Low-Constraint Conditions2.2 ISO

12、 Standards:4ISO 22889 Metallic materials Method of Test for the Determination of Resistance to Stable Crack Extension UsingSpecimens of Low Constraint1 This test method is under the jurisdiction of ASTM Committee E08 on Fatigue and Fracture and is the direct responsibility of Subcommittee E08.07 on

13、FractureMechanics.Current edition approved May 1, 2016Nov. 1, 2018. Published June 2016January 2019. Originally approved in 2016. Last previous edition approved in 2016 as E303916.DOI: 10.1520/E30391610.1520/E3039182 The boldface numbers in parentheses refer to a list of references at the end of thi

14、s standard.3 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.4 Available from International Organization for St

15、andardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,Switzerland, http:/www.iso.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous v

16、ersion. 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 document.Copyright ASTM Internat

17、ional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1ISO 14456 Steel Charpy V-notch Pendulum Impact Test Instrumented Test Method2.3 API Recommended Practice:5API Recommended Practice 5L3 Drop-Weight Tear Tests on Line Pipe3. Terminology3.1 Symbols:a = crack siz

18、e, mman = initial notch depth, mmb = specimen ligament size (b=W-a), mmb0 = initial ligament size (b0=W-an), mmCv = full-size Charpy V-notch absorbed energy, JB = specimen thickness, mmL = specimen length, mmM = total mass of the moving striker (hammer), kgP = force, kNPm = maximum force applied by

19、the hammer during the test, kNrp = plastic rotation factorS = specimen span between anvil contact points (S = 254 mm for standard DWTT tests), mmS = specimen span between anvil contact points (S = 254 mm for standard DWTT-type tests), mmt0 = time at the beginning of specimen deformation, sv0 = initi

20、al striker impact velocity, m/sW = specimen width, mmy = yield strength, MPa = load-line displacement (LLD), mmm = load-line displacement (LLD) at maximum force, mm = absolute value of slope of the ln(P/Pm) versus (-m)/S curve as specified in Section 8.3.2 Acronyms:CTOA = crack-tip opening angle, de

21、greeCTOAB/2 = critical crack-tip opening angle in the steady-state stage as determined by this test method, degreeDWTT = drop-weight tear testSE(B) = single-edge bend specimenS-SSM = simplified single-specimen CTOA test method3.3 Definitions:3.3.1 crack-tip opening angle (CTOA), deg, nangle formed b

22、etween the fractured surfaces measured at the crack tip.3.3.2 critical crack-tip-opening angle (CTOAB/2), deg, nsteady-state value of CTOA as measured by this test method,intended to approximate the CTOA on the mid-thickness plane as the angle between the crack flanks. The crack flanks extend fromth

23、e crack tip to one-half of the DWTTDWTT-type specimen thickness (B/2) behind the crack tip (see Fig. 1) during steady-statepropagation.3.3.2.1 Discussion5 Available from American Petroleum Institute (API), 1220 L. St., NW, Washington, DC 20005-4070, http:/www.api.org.FIG. 1 Measurement point for CTO

24、AB/2 and location of mid-thickness planeE3039 182The shape of the tearing crack is initially dominated by a flat tunneling region that often transitions from flat to slant fracture, andtends to approach a constant tunneling shape after a crack extension of approximately one specimen thickness. The C

25、TOA tendsto approach a constant, steady-state value (CTOAB/2) during propagation through the mid-portion of the original ligament. It mustbe recognized that the CTOA often depends on where it is measured, that is, at what distance behind the crack tip, and themeasurement is complicated by tunneling.

26、 In this test method, CTOAB/2 is defined as the angle between the crack flanks extendingfrom the crack tip to a distance B/2 along the crack surface. This parameter may be compared with optical measurements made,for example, using pictures of the specimen surface taken with a high-speed camera. Disc

27、ussion of the optical method is includedin Test Method E2472.3.3.2.2 DiscussionThis procedure uses CTOAB/2 for the critical crack-tip-opening angle to distinguish it from the CTOAc in Test Method E2472 andISO 22889, in which CTOA is measured or calculated at 1 mm behind the current crack tip.4. Summ

28、ary and Significance4.1 The objective of this test method is to use measurements of force (P) versus load-line displacement () to derive the criticalsteady-state crack-tip opening angle (CTOAB/2) based on the simplified single-specimen method (S-SSM) (2). The S-SSM is afurther development of the pre

29、vious two-specimen CTOA method (3) and simplification of a single-specimen CTOA method (4).In addition, the calculation of CTOA requires a value for the plastic rotation factor (rp). For typical pipe steels, values of rp havebeen estimated experimentally (5), and will be discussed in Section 8.4.2 T

30、he CTOAB/2 value derived according to this test method is close to the value in the high-constraint mid-thickness regionof the DWTTDWTT-type specimens, and is significantly lower than the surface CTOA values measured optically (5, 6). Thisreflects the effects of through-thickness constraint and the

31、resulting crack-tip tunneling.4.3 Steady-state ductile crack propagation velocities range between 12-20 m/s in DWTTDWTT-type specimens impacted witha hammer velocity of 5 m/s. The crack velocity decreases as toughness increases (6). DWTTDWTT-type specimens of steels testedat room temperature usually

32、 exhibit shear fracture under impact loading; that is, the flat (tunnelling) morphology at crack initiationusually transitions to a near-45 slant fracture that is considered to be a shear morphology. For pipe steels, this mimics the fracturemode observed in full-scale pipe burst tests.4.4 The appara

33、tus, specimen dimensions and testing procedure in this test method are the same as those described in TestMethod E436 orAPI RP5L3 and Test Method E2298, see Section 2. The intent is to adopt the standardized DWTT test procedures,machines (for example, hammer and anvil supports), and instrumentation

34、requirements to the maximum extent possible. Thefollowing sections provide specific requirements, procedures and calculations for determining CTOA.5. Apparatus5.1 The test shall be conducted using a test machine that has sufficient energy to completely break the specimen in one impact.The key dimens

35、ions, shown in Fig. 2, are: distance between supports (span) S = 254 mm (10 in.), radius of impact hammer strikingedge = 25.4 mm (1 in.), and radius of fixed support anvils = 19 mm (0.75 in.). Drawings of the test fixture and specimen can alsobe found in Test Method E436 or API RP 5L3.5.2 The initia

36、l velocity v0 of the hammer at impact shall be 5 m/s v0 10 m/s and shall be known within 6 5%, as discussedbelow.5.3 For force measurement and displacement determination, the provisions of Test Method E2298 shall apply. Instrumentationshall be used to determine force-time or force-displacement curve

37、s.5.4 Force Measurement:5.4.1 Force shall be measured by means of an electronic sensor (piezoelectric load cell, strain gauge load cell or a forcemeasurement derived from an accelerometer).5.4.2 The force measuring system (including strain gauges, wiring, and amplifier) shall have a bandwidth of at

38、least 100 kHzas discussed in Guide E1942.5.4.3 The signal shall be recorded without filtering. Post-test filtering, however, is allowed as detailed in Test Method E2298,7.2 but efforts should be taken to avoid introducing errors through filtering, as discussed in Guide E1942.5.4.4 Calibration of the

39、 recorder and measurement system may be performed statically in accordance with the accuracyrequirements given in 5.4.4.1. For pendulum machines, it is recommended that the force calibration be performed with the strikerattached to the pendulum assembly. The strain gauge signal conditioning equipmen

40、t, cables, and recording device shall be usedin the calibration. In most cases, a computer is used for data acquisition and the calibration shall be performed with the voltageread from the computer. The intent is to calibrate with the electronics and cables which are used during actual testing.E3039

41、 1835.4.4.1 The static linearity and hysteresis error including all parts of the force measurement system up to the recording apparatusshall be within 6 2 % of the recorded force, between 50 % and 100 % of the nominal force range, and within 6 1 % of the fullscale force value between 10 % and 50 % o

42、f the nominal force range as detailed in Test Method E2298, 7.2.4.1.NOTE 1For testing in accordance with this test method, it is recommended to calibrate the instrumented striker up to 500 kN.5.4.5 Recalibration shall be performed if the instrumented striker has undergone dismantling or repair, unle

43、ss it can be shownthat removal of the striker from the test machine and subsequent re-attachment to the machine does not affect the calibration.5.5 Displacement Determination:5.5.1 Displacement shall be measured using a non-contacting transducer according to 5.5.4 or calculated using force-timemeasu

44、rements with Newtons equations of motion as outlined in 5.5.2.5.5.2 Assuming a rigid striker of mass m with an initial velocity v0 the velocity v(t) at the contact point as a function of elapsedtime is calculated as:vt!5v02 1m*t0tPt!dt (1)If the specimen is assumed not to lift off at the anvils the

45、bending displacement (t) is evaluated from:t!5*t0tvt!dt (2)5.5.3 For drop weight and pendulum machines, the initial impact velocity needed to perform the above integrations is calculatedfrom:v05=2gh0 (3)where:g = local acceleration due to gravity, andh0 = height of striker from point of release to p

46、oint of initial impact.5.5.3.1 Alternatively, for drop weight and pendulum machines, it is acceptable to use for v0 the optically measured velocityregistered when the pendulum passes through its lowest position and strikes the specimen.5.5.4 Displacement can also be determined by non-contacting meas

47、urement of the displacement of the striker relative to theanvil using optical, inductive, or capacitive methods. The signal transfer characteristics of the displacement measurement systemshall correspond to that of the force measuring system in order to minimize phase difference and data skew errors

48、, as discussedin Guide E1942. The displacement measuring system shall be designed for maximum nominal values of 40 mm. Linearity errorsin the measuring system shall yield measured values to within 6 2 % over a range of 1 mm to 40 mm. Measurements up to 1 mmmay not be sufficiently accurate to determi

49、ne the displacement within 6 2 %. In this case, the displacement of the specimen shallbe determined from the time measurement and the striker impact velocity as indicated in Eq 1 and Eq 2.FIG. 2 Dimensions (in mm) of the machine-notched specimen (top) and supporting anvils (bottom). The anvils are fixed in position.E3039 1845.6 The recording apparatus (that is, high-speed data acquisition system and instrumented striker) shall comply with TestMethod E2298 Section 7. Data acquisition systems that are commercially available for instrumented C