1、Designation: D1780 05 (Reapproved 2012)Standard Practice forConducting Creep Tests of Metal-to-Metal Adhesives1This standard is issued under the fixed designation D1780; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This practice covers the determination
3、 of the amount ofcreep of metal-to-metal adhesive bonds due to the combinedeffects of temperature, tensile shear stress, and time.NOTE 1Since the characteristics that render a material resistant tocreep under the condition of test are not yet completely known, the detailsof the procedure considered
4、herein are those known to have importantinfluences. Since other equally important characteristics may be discov-ered in the future, the recommended details are largely advisory in nature.1.2 Test periods depend upon the reasonable life expectedfrom the material in service. The uncertainties of extra
5、polationshould be considered in deciding upon the length of the test.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use.
6、It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D907 Terminology of AdhesivesD1002 Test Method for Apparent Shear Strength of
7、Single-Lap-Joint Adhesively Bonded Metal Specimens by Ten-sion Loading (Metal-to-Metal)3. Terminology3.1 DefinitionsMany of the terms in this practice aredefined in Terminology D907.3.2 Definitions of Terms Specific to This Standard:3.2.1 creep, nthe time-dependent part of the strain thatresults fro
8、m exposure to a constant temperature and load (Note2). That is, the creep at a given elapsed time is equal to the totalstrain at the given time minus the instantaneous strain (Note 3)on loading. The creep extension is expressed as a percentage,that is, the extension divided by the initial unstretche
9、d lengthmultiplied by 100.NOTE 2Constant-stress creep tests are desirable. The usual one is aconstant deadweight load test. Creep tests made by means of springloading or fixtures which involve deflection or strain measurements in thefixture for the application of load are unsatisfactory. However, if
10、 the totaldeformation or extension in the adhesive is large, corrections must bemade to compensate for the decrease in stress because of the extension inthe adhesive.NOTE 3Since the time-dependent strain develops rapidly even duringthe application of the load, the instantaneous strain for recovery i
11、s usuallydifficult to determine, except in the arbitrary manner given in thedefinitions of instantaneous strain and instantaneous recovery.3.2.2 deformation, nthe total strain at any specific time.3.2.3 failure, nrupture of the specimen, or exceeding thestrain requirements of a specific design.3.2.4
12、 instantaneous recovery, nthe decrease in strain oc-curring immediately upon unloading a specimen. As in instan-taneous strain, a more reproducible value is obtained if thedecrease in strain is measured after a given small increment oftime (such as 1 min) following unloading. The increment oftime us
13、ed shall be specified. The instantaneous recovery shallbe expressed in the same units as strain, that is, the decrease inlength divided by the gage length usually, in inches per inch.3.2.5 instantaneous strain, nthe strain occurring immedi-ately upon loading a creep specimen. Since it is nearlyimpos
14、sible to obtain strain readings at the instant of loading,the strain after a given small increment of time (such as 1 min)after loading is a more reproducible value. The increment oftime used shall be specified. The instantaneous strain shall beexpressed in the units as strain, that is, the extensio
15、n divided bythe gage length, usually in inches per inch.3.2.6 recovery, nthe time-dependent portion of the de-crease in strain following unloading of a specimen at the sameconstant temperature as the initial test. Recovery is equal to thetotal decrease in strain minus the instantaneous recovery (see
16、Note 3). The recovery shall be expressed in the same units asinstantaneous recovery.1This practice is under the jurisdiction of ASTM Committee D14 on Adhesivesand is the direct responsibility of Subcommittee D14.80 on Metal BondingAdhesives.Current edition approved Oct. 1, 2012. Published October 20
17、12. Originallyapproved in 1960. Last previous edition approved in 2005 as D1780 05. DOI:10.1520/D1780-05R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the stan
18、dards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Significance and Use4.1 This practice provides information on the creep ofbonded metal parts subjected to combined effects oftemperature
19、, shear, and time.5. Possibilities and Limitations5.1 The primary use of creep tests is to provide basic datafor the choice of safe working stresses for applications inwhich allowable deformation within the service life of thestructure is the criterion of failure.5.2 Creep is an extremely sensitive
20、index of strength, andusually does not vary as a linear function of stress. (It dependson the material, stress, temperature, and time.)5.3 In the application of the following test requirements andrecommendations it is assumed that the test specimens of agiven adhesive bond are essentially comparable
21、 and trulyrepresentative of the material. In tests conducted to show theeffects of temperature or stress as variables, great care must beused to ensure that the specimens are representative of theadhesive bond. Departure from this assumption may introducediscrepancies as great as, if not greater tha
22、n, those due todeparture from details of procedure outlined in this practice.6. Apparatus6.1 Testing Machine, capable of producing a tensile load onthe specimen at the rate indicated in 10.2 and consisting of thefollowing:6.1.1 Fixed MemberA fixed or essentially stationarymember, carrying one grip.6
23、.1.2 Movable MemberA movable member, carrying asecond grip.6.1.3 GripsThe grips, designed to minimize eccentricloading of the specimen. A swivel or universal joint near eachend of the specimen is desirable wherever possible.6.2 MicroscopeA calibrated microscope having a Filarmicrometer eyepiece and
24、a 10 objective lens.7. Temperature Control and Measurement7.1 For tests at a particular temperature, maintain thespecimen at a constant temperature, preferably by a suitableautomatic control device. Where a furnace or cold box is used,it is desirable to locate this unit in a constant-temperature roo
25、mto aid in temperature control.7.2 The determination of the temperature of the specimenduring the test is the most important single measurement inconnection with creep testing, because small variations intemperature may produce large changes in creep rate. Maintaina uniform temperature over the test
26、 section with a maximumvariation not to exceed 61C (1.8F). Hold the maximumdeviation of the temperature throughout the duration of the testperiod to 61C. State any fluctuation beyond this tolerance inreporting the test. Make the range of the normal control cyclea matter of record for the apparatus.7
27、.3 Take care to obtain reliable and accurate master tem-perature standards and check these at suitable intervals. Whenthermocouples are used in the test, use one of knowncalibration, checked before testing and after long-time expo-sures.7.4 Use two thermocouples for measuring temperatures ofthe spec
28、imens throughout the test. Place these on oppositeedges of the specimen at the end of the lap joint in the bondline. In furnaces not having equalized temperature over a51-mm (2-in.) zone place additional thermocouples at each endof the 51-mm center section of the specimen to ensure equaltemperature
29、distribution.7.5 Keep a continual record of the thermocouple measure-ments throughout the test. An automatic recorder of thestrip-chart type is preferred. If automatic equipment is notavailable, make visual observations at sufficiently close inter-vals of time to ensure accuracy of temperature contr
30、ol through-out the test.8. Vibration Control8.1 Since creep tests especially are quite sensitive to shockand vibration, select the location of the testing apparatus for aminimum of disturbance. When the possible locations are notfree of vibrations, design the test equipment and mounting sothat the s
31、pecimen is isolated from shock and vibration.9. Test Specimens9.1 Prepare test panels, 190.5 by 305 mm (712 by 12 in.)from 1.6-mm (0.063-in.) metal, as shown in Fig. 1. Machine alledges of the panels within the completed bonded lap-joint trueand smooth before the panels are cleaned and bonded.9.2 Cl
32、ean and bond the panels in accordance with theadhesive manufacturers instructions. The bonded lap for alltest panels is 12.70 6 0.25 mm (0.500 6 0.010 in.). Cut panelsinto 25-mm (1-in.) wide specimens for testing. Ensure all edgesto be smooth and free of burrs, tool marks, and scratches. Fig.2 shows
33、 the location of the scribe lines used to determine thedeformation.10. Number of Test Specimens10.1 Test a minimum of three specimens from each panelfor each plotted point on the curve.10.2 Test a minimum of two specimens from each panel todestruction in tensile shear in accordance with Test MethodD
34、1002 at the corresponding creep test temperature. The load-ing rate is 8.3 to 9.7-MPa (1200 to 1400-psi) shear stress perminute in the adhesive.11. Procedure11.1 Make three fine scribe lines across the machinedvertical edges of the specimen at each edge of the joint exposedby machining of the specim
35、ens from the bonded panel. Placeone scribe line across the center of the lap joint and the othertwo at a distance of 0.76 6 0.25 mm (0.030 6 0.010 in.) fromthe ends of the lap joint (see Fig. 2).11.2 Record the readings of the Filar micrometer prior to theapplication of the test temperature (if diff
36、erent from roomtemperature), immediately after the test temperature is reached,D1780 05 (2012)2at intervals during any preshrinkage treatment, and immedi-ately after the test load is applied. The total number andintervals of subsequent readings depend on the adhesive.11.3 Apply the prescribed load,
37、measured to within 1 %, assoon as the temperature equilibrium in the specimen is ob-tained or within a time period not to exceed 60 min. Apply thetest load quickly, but gently. Direct deadweight loading or theuse of a simple lever is preferred, provided the laboratory isfree of shock and vibration.1
38、1.4 Take great care to avoid eccentricity. Check the entireassembly of specimen and loading mechanism for alignment ina suitable fixture properly instrumented prior to the test. Longpull rods facilitate obtaining proper alignment. Make changesin the assembly until alignment is obtained.11.5 Measure
39、the deformation directly by observing thedisplacement of the three scribe lines with the calibratedmicroscope. Measure the deformation to an accuracy of 0.025mm (0.001 in.) at such intervals of time that a smoothtimedeformation curve may be plotted. The exact timeintervals will depend upon the adhes
40、ive being tested and thecreep rate of the joint.11.6 Throughout the duration of the test, keep records of thedeformation so as to maintain a complete record of thedeformation and the time. Determine the deformation of eachspecimen by averaging the deformation measurements at theprescribed points on
41、the joint. Measure the bond line thicknessto the nearest 0.0025 mm (0.0001 in.).11.7 Exercise care in loading the specimen to keep theamount of vibration and shock at a minimum in order to ensurethe accuracy of the initial measurements. Take the sameprecaution throughout the test period.11.8 After u
42、nloading the specimen at the end of the exten-sion measurements, make a record of the recovery versus thetime occurring in the test specimen. Exercise caution whenloading and unloading the specimen to obtain satisfactoryoverall accuracy of the tests.12. Fundamental Measurements12.1 Measurements to b
43、e recorded include: instantaneousstrain, deformation, length of time, load, instantaneousrecovery, adhesive bond area, glue line thickness, and tempera-ture. Of these eight quantities, length of time, bond area, andbond line thickness present little difficulty, while frictionaleffects are the only p
44、articular considerations in connection withthe applied load. Measurement of deformation and temperatureare more difficult.13. Plotting Results13.1 The deformationtime curves may be plotted onordinary rectangular coordinates. Express time in hours anduse as the scale for the abscissa.Metric Equivalen
45、tsin. 0.005 0.010 0.063 0.10 0.125 0.500 1.000 5 7.5 12mm 0.127 0.254 1.600 2.54 3.175 12.7 25.4 127 190.5 305FIG. 1 Test Panel Construction and Orientation of Test Specimens in PanelMetric Equivalentsin.mm0.0300.2500.7626.350FIG. 2 Creep Rupture Test Specimen Showing Location of ScribeLines for Def
46、ormation MeasurementD1780 05 (2012)313.2 It is often more useful to plot creep as a function oftime on log-log coordinates. Such plots often result in nearlystraight-line diagrams, which facilitate interpolation andextrapolation, as well as interpretation.14. Report14.1 Report the following informat
47、ion:14.1.1 Complete identification of the adhesive tested, in-cluding type, source, manufacturers code number, etc.,14.1.2 Identification of materials used as adherends andmethod of surface preparation used,14.1.3 Method of application of adhesive and curing condi-tions used,14.1.4 Average thickness
48、 of adhesive layer after formationof the joint, within 0.025 mm (0.001 in.). Method of obtainingthe thickness of the adhesive layer, including procedure,location of measurements, and range of measurements.14.1.5 Conditioning procedure used, if any,14.1.6 Testing temperature, C (F),14.1.7 Adhesive sh
49、ear stress applied, kgN/mm2(psi),14.1.8 Total test time, h,14.1.9 Initial deformation, mm (in.),14.1.10 Total deformation, mm (in.), at specific timeintervals,14.1.11 Total creep, mm (in.), for the period of the test,14.1.12 Creep rate, mm/h (in./h),14.1.13 Specimen number, and14.1.14 Failure, if any.15. Keywords15.1 creep; failure; load; recovery; strain; stressASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that d
