ASTM F269-1960(2009) Standard Test Method for Sag of Tungsten Wire《钨丝下垂的标准试验方法》.pdf

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1、Designation: F 269 60 (Reapproved 2009)Standard Test Method forSag of Tungsten Wire1This standard is issued under the fixed designation F 269; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in p

2、arentheses 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 a determination of the sagproperties of tungsten wire 0.030 in. (0.76 mm) and over indiameter.1.2 The values stated in inc

3、h-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is t

4、heresponsibility of the user of this standard to consult andestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2. Apparatus2.1 Bell Jar EnvelopeAsuitable envelope surrounding thetest apparatus. The envelope may consist of a glass

5、 bell jar,preferably of a heat resistant glass (WarningA protectivemedium shall be provided over an exposed glass to preventinjury by flying glass in the event of an explosion), or may beconstructed of metal, in which case a transparent window shallbe provided in order that the behavior of the speci

6、men undertest may be observed. The envelope may be rigidly supportedin a fixed position or may by suspended in such a manner thatit can be raised or lowered into position over the test apparatus.Ameans shall be provided for maintaining within the envelopean atmosphere and steady supply flow of hydro

7、gen. A flowmeter shall be incorporated in the hydrogen line so thatmeasurement and control of the gas flow may be maintained.The hydrogen line shall discharge at the upper levels of theenvelope and shall be baffled by a suitable diffusing device sothat no direct stream of the gas will play upon the

8、testspecimens.2.2 Specimen SupportA suitably designed support andclamping device for holding the specimen within the envelopeduring testing. This support, which may be rigidly fixed orcapable of being raised into or lowered from the envelope,shall be made from a suitable metallic conductor so thatel

9、ectrical current from the power supply may be used to heatthe test specimen. An insulated clamping fixture shall beprovided at the top of the support so that the hairpin testspecimen will be firmly held. This clamping device shall becapable of rotating 90 on its axis in order that the testspecimen m

10、ay be heated both in a vertical-position with itsapex down and in a horizontal position. A means shall beprovided for accomplishing this rotation without requiring theremoval of the test specimen from the clamping fixture.2.3 WeightsA set of weights comprising loads of 3, 4, 6,7, 9, 10, and 13 lb (1

11、.4, 1.8, 2.7, 3.2, 4.1, 4.5, and 5.9 kg). Ahook shall be provided for attaching the required weight to theapex of the test specimen. This hook should be made fromtungsten wire and should be capable of supporting the heaviestweight at the elevated temperature of testing, without fear ofbreaking.NOTE

12、1A tungsten wire with a diameter of 0.080 in. is recommendedfor use as a hook.2.4 Cathetometer or any other suitable instrument for mea-surement of the vertical displacement of the test specimen thatresults from the sag test. This instrument shall have a suitablescale so that movement of the specime

13、n of as little as 0.5 mmmay be read.2.5 Power SupplyAsupply of electric current sufficient toheat the test specimen to the required test temperatures. Ameter shall be provided in this supply to permit measurementof the current to an accuracy of 62%.3. Materials3.1 Hydrogen used for the test atmosphe

14、re shall have apurity meeting the following requirements:3.1.1 Moisture (water), not more than 2.5 g/1000 ft3(2.5g/28 m3) as indicated by a dew point of 65C or below.3.1.2 Oxygen, not more than 10 ppm.1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct r

15、esponsibility of Subcommittee F01.03 on MetallicMaterials.Current edition approved May 1, 2009. Published July 2009. Originally approvedin 1952. Last previous edition approved in 2002 as F 269 60 (2002).1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-29

16、59, United States.3.1.3 Hydrocarbons (plus CO and CO2), not more than 20ppm.3.1.4 Nitrogen, not more than12 %.4. Test Specimen4.1 SurfaceThe specimen of tungsten wire to be tested forsag shall have a clean, bright surface and shall be at least 15 in.in length.4.2 FormingWith the aid of external heat

17、, the test speci-men shall be bent into a hairpin-shape until the distancebetween the ends is 1 in. The hairpin is formed by bending thewire around a pin whose diameter is approximately twice thatof the test specimen.NOTE 2Note more than 20 % of the hairpin length (measured fromthe apex) shall be he

18、ated above a black heat when the hairpin is formed.Also, the legs of the formed hairpin shall lie in the same plane.4.3 Test LengthThe formed test specimen shall be ofsufficient length so that when clamped in the fixture, theexposed lengths measured from the top of the apex will be asfollows:Wire Di

19、ameter ofTest Specimen, in. (mm)ExposedLength,L, in. (mm)0.0300 to 0.0349 (0.762 to 0.886) 418 (104)0.0350 to 0.0449 (0.889 to 1.140) 412 (114)0.0450 to 0.0549 (1.143 to 1.394) 518 (130)0.0550 to 0.0649 (1.397 to 1.648) 558 (143)0.0650 to 0.0749 (1.651 to 1.902) 6 (152)0.0750 to 0.0849 (1.905 to 2.1

20、56) 614 (160)0.0850 to 0.1000 (2.159 to 2.540) 612 (165)5. Procedure5.1 Mount the test specimen vertically downward in the testapparatus. Move the apparatus, with the specimen in place, intothe bell jar envelope. Introduce sufficient hydrogen into the belljar at a positive flow to form a safe protec

21、tive atmosphere forthe test specimen. Attach the appropriate weight to the testspecimen as indicated in the following table:Wire Diameter ofTest Specimen, in. (mm)Weight,lb (kg)0.0300 to 0.0349 (0.762 to 0.886) 3 (1.4)0.0350 to 0.0449 (0.889 to 1.140) 4 (1.8)0.0450 to 0.0549 (1.143 to 1.394) 6 (2.7)

22、0.0550 to 0.0649 (1.397 to 1.648) 7 (3.2)0.0650 to 0.0749 (1.651 to 1.902) 9 (4.1)0.0750 to 0.0849 (1.905 to 2.156) 10 (4.5)0.0850 to 0.1000 (2.159 to 2.540) 13 (5.9)5.2 After the bell jar envelope is completely flushed withhydrogen, raise the temperature of the test specimen at aconstant rate of 26

23、00 K true temperature in 1 min and hold atthat temperature for 5 min, after which lower the current tozero in 1 min at a constant rate.NOTE 3Variables that influence temperature determination by electri-cal current are as follows:(1) Nature of wire surface,(2) Hydrogen flow through bell jar envelope

24、,(3) Purity and moisture content of hydrogen,(4) Contact of test specimen in it supports, and(5) Measurement of the diameter of the test specimen.Variables that influence temperature determination by optical methods are asfollows:(1) Variations in wall thickness of glass,(2) Films on glass,(3) Defec

25、ts in glass,(4) Inaccuracies inherent in optical pyrometer, and(5) Nature of wire surface.5.3 When the test apparatus has cooled, remove the weightand move the test specimen through an angle of 90 so that theplane formed by the legs of the specimen is horizontal.Measure the vertical distance of the

26、apex in millimeters andrecord as the zero point or initial reading.5.4 Raise the temperature of the test specimen at a constantrate of 2600 K in 1 min and hold at that temperature for 5 minbefore removing the power.5.5 When the apparatus and specimen have cooled, measurethe sag before removing the s

27、pecimen from the apparatus.Measure the vertical distance of the apex of the specimen inmillimeters and record as the final reading. The sag is definedas the difference between the initial and final readings afterbeing held at 2600 K for 5 min.6. Report6.1 Report the following information:6.1.1 Name

28、of the manufacturer of the wire,6.1.2 Manufacturers wire type,6.1.3 Metal lot number,6.1.4 Ingot number,6.1.5 Wire size, and6.1.6 Sag results in millimeters on each ingot.7. Keywords7.1 creep testing; hydrogen atmosphere; sag properties;tungsten wireASTM International takes no position respecting th

29、e validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard i

30、s subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International He

31、adquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This s

32、tandard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).F 269 60 (2009)2