ASTM B106-2008 Standard Test Methods for Flexivity of Thermostat Metals《恒温金属挠性的标准试验方法》.pdf

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1、Designation: B 106 08Standard Test Methods forFlexivity of Thermostat Metals1This standard is issued under the fixed designation B 106; 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 parenthe

2、ses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover the determination of flexivity(a measure of thermal deflection rate or deflection temperaturecharacteristics) of thermostat met

3、als.1.1.1 Test Method ATested in the form of flat strip0.015 in. (0.38 mm) or over in thickness.1.1.2 Test Method BTested in the form of spiral coils lessthan 0.012 in. in thickness.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathemati

4、calconversions 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 theresponsibility of the user of this standard to become familiarwith all hazards including

5、 those identified in the appropriateMaterial Safety Data Sheet (MSDS) for this product/materialas provided by the manufacturer, to establish appropriatesafety and health practices, and determine the applicability ofregulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 389

6、Test Method for Thermal Deflection Rate of Spiraland Helical Coils of Thermostat Metal3. Terminology3.1 Definitions:3.1.1 thermostat metal, na composite material in the formof sheet or strip comprising two or more metallic layers ofdiffering coefficients of thermal expansion, such that the radiusof

7、curvature of the composite changes with temperaturechange.3.1.2 flexivity (F), nthe change of curvature of the longi-tudinal center line of the specimen per unit temperature changefor unit thickness, given by the following equation:F 5 t1/R2! 2 1/R1!T22 T1(1)To determine the flexivity between any tw

8、o temperatures, T1and T2, it is necessary to measure the curvature 1/ R1and 1/R2at temperature T1and T2, respectively. To find the curvature ateither temperature (Fig. 1 and Fig. 2), measure the distance D.The curvature is given by the following equation:1/R 5 8D/Q21 4Dt 1 4D2! (2)where:R = radius o

9、f curvature of the longitudinal center line of thespecimen, in. (mm),t = thickness of test specimen, in. (mm),Q = distance between support points, in. (mm), andD = for point support (simply supportedbeam), = perpendicular distance between the longitu-dinal center lines of the lower surface of the sp

10、ecimenmidway between the point supports and the straightline joining the support points, in. (mm).4. Significance and Use4.1 These test methods are used for determining response totemperature change or flexivity of thermostat metal. Theflexivity is calculated from the temperatures, dimensions ofspec

11、imen, and the relative movement of the specimen. Thesimple beam method (Method A) is the method for certifica-tion. Any use of the spiral coil method (Method B) is to bemutually agreed upon between the user and supplier.TEST METHOD AFLAT STRIPS5. Apparatus5.1 Specimen Carrier, provided with two coni

12、cal supportsfor locating the specimen. The test length (that is, the distancebetween the point of contact of the specimen with one supportand the point of contact of the specimen with the other support)shall be known to within 60.005 in. (0.13 mm), and the line ofplane passing through the points of

13、contact shall be horizontal.The specimen carrier and supports shall hold the specimenwithout constraint so that the curvature, due to its deflection,will follow a vertical plane passing through the line joining thepoints of contact between specimen and supports. Suitablemeans shall be used to ensure

14、 test length.1These test methods are under the jurisdiction of ASTM Committee B02 onNonferrous Metals and Alloys and are the direct responsibility of SubcommitteeB02.10 on Thermostat Metals and Electrical Resistance Heating Materials.Current edition approved April 1, 2008. Published May 2008. Origin

15、allyapproved in 1984. Last previous edition approved in 2002 as B 106 96 (2002)e1.2The boldface numbers in parentheses refer to a list of references at the end ofthis standard.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 Micro

16、metertraveling microscope, or equivalent de-vice, so connected to the specimen carrier that expansionduring heating of the carrier or connecting parts will not causeappreciable displacement of the measuring device with respectto the supports.5.3 BathA stirred liquid bath or uniformly heated enclo-su

17、re in which the specimen carrier, together with adjustableelectric heating source is placed. The specimen needs to bemaintained at the desired temperatures, with a variation intemperature throughout the gage length of the specimen not toexceed 0.5 % of the temperature range used in the test.5.4 Temp

18、erature Measuring Apparatus, of such accuracythat the individual temperatures shall be known to within60.5F (0.3C).5.5 Deflection IndexMeans shall be provided for measur-ing the deflection of the specimen at a point midway betweenthe points of support and along the vertical line intersecting theline

19、 joining the points of support. Such means may comprise atransmission rod disposed with its axis vertical and terminatingin a point or knife-edge, which shall engage the specimenmidway between the points of contact with the supports.5.5.1 The transmission rod shall be mounted in such amanner that it

20、 is free to move in the direction of its axis. Therod shall bear at its free end an index suitable for microscopicalobservation, or else an electrical contact with which a mi-crometer will permit the changes of the deflection of specimento be accurately observed. Alternatively, the deflection of the

21、midpoint of the specimen may be directly observed by opticalmeans whose line of sight is horizontal and passes through thevertical line through the midpoint of the specimen.Amicrome-ter screw with extended spindle making direct contact with thespecimen may be used. In this case, electrical means sha

22、ll beprovided that will indicate contact without significant distur-bance of the specimen. The measurement of the position of themidpoint of the test specimen shall be of such accuracy that theindividual positions at the test temperatures shall be known towithin 60.0002 in. (0.005 mm).5.5.2 If a tra

23、nsmission rod is used, it and any attached partsshall be of such weight or so counterweighted that they will notcause a deflection greater than 1 % of the maximum to beproduced by the action of the thermostat metal alone. Whenfree, the thermostat metal assumed very nearly a circularcurvature. Concen

24、trated loading at the center of the specimenwill cause the curvature to be other than circular and may causesignificant errors in the evaluation of flexivity. The location ofthe line passing through the points of contact between speci-men and supports shall be known, with reference to the scale ofth

25、e micrometer, to within 60.002 in. (0.05 mm).5.6 All metallic components of the flexivity apparatusshould be made of very low coefficient of thermal expansioncomponents. The recommended material is Invar.36. Test Specimens6.1 The test specimen shall be in the form of a strip thatdisplays no apparent

26、 initial irregularity of curvature.6.2 The maximum thickness shall not be greater than theminimum thickness by more than 1 % of the latter.6.3 The width shall be related to the thickness in accordancewith Fig. 3. Preferred widths are to be used whenever possible.The maximum width shall not exceed th

27、e minimum width bymore than 2 % of the latter.6.4 The length shall be such as to allow a distance betweensupports that bears the relation to the thickness in accordancewith Table 1 and to allow a distance beyond the supports notless than the width.6.5 The thickness of the specimen shall be determine

28、dwithin 60.0001 in. (0.002 mm) by means of a screw microme-ter or an equivalent method.6.5.1 For specimens less than 0.050 in. (1.27 mm) inthickness, special precautions are necessary, such as the use ofa micrometer reading directly to 0.0001 in. (0.002 mm).Suitable optical methods may also be used.

29、6.5.2 The average thickness may be calculated from mea-surements of length, average width, weight, and density. Whenthe density is unknown, it may be determined by weighing asample of at least 10 g first in air and then in water. The density3Invar is a registered trademark of CRS Holding, a subsidia

30、ry of CarpenterTechnologies.FIG. 1 Test for Flexivity of Thermostat MetalsFIG. 2 Typical Apparatus DesignB106082in grams per cubic centimetre is equivalent to the weight in airdivided by the loss of weight due to submergence in water. Thetemperature of the water shall be approximately the same astha

31、t of the balance room to avoid errors due to convectioncurrents. For the accuracy required, no corrections are neces-sary for the temperature of the water or for the buoyancy of theair. However, care shall be exercised to remove all air bubblesfrom the sample when weighing it in water and to avoid t

32、hepresence of grease or other films on the surface of the water. Tothis end it is recommended that after a preliminary cleaning toremove obvious dirt, the sample be attached to a fine wire to beused later in suspending it while weighing and thoroughlyrinsed, first in ether, then alcohol and finally

33、water, beforeimmersing in the water to be used for weighing.7. Preparation of Test Specimen7.1 After being roughly cut or sheared from the sample,finish the test specimen to size by careful machining or filing.Remove the amount of material extending a distance not lessthan twice the thickness along

34、each edge of the specimen, toeliminate material damaged by preliminary shaping. Slit edgeswith a minimum of burr may also be used.7.2 When the specimen has been finished to size, make anynecessary reference marks (by such means as a sharp drill,scribing tool, or milling cutter). Determine and record

35、 therelative locations of the reference marks. Do not use centerpunches or similar means because of the distortion produced.7.3 It is recommended that the grain run along the length ofthe specimen.8. Procedure8.1 StabilizationAfter all preparatory work has been com-pleted, subject the test specimen

36、to a stabilizing heat treatmentto relieve internal stresses. This treatment may consist ofheating the specimen, while free to bend, for a prescribed timeand temperature. The details of the stabilizing procedure willdepend upon the characteristics of the thermostat metal beingtested and shall be as m

37、utually agreed upon between themanufacturer and the purchaser.8.2 Test RoutineMount the specimen on the support onthe specimen table. With the transmission rod in place take azero reading at room temperature. Apply slight mechanicalpressure and then remove the rod at a point near the center ofthe sp

38、ecimen. If appreciable zero shift is apparent withrepeated applications of pressure, determine the cause andcorrect before proceeding with the test.8.3 When satisfactory initial conditions have been estab-lished, make observations of deflection and temperature at lowtemperature and record the result

39、s.8.4 Adjust the temperature of the specimen to the high valuedesired. Measure and record the temperature of the specimen atpoints on or near the center and ends after sufficient time forstabilization.8.5 Measure and record the deflection.FIG. 3 Width of Test SpecimenTABLE 1 Gage Length of Test Spec

40、imen (Test Method A)Specimen Thickness Gage Lengthin. mm in. mm0.015 to 0.0199, incl 0.38 to 0.509, incl 212 612 63.5 6 12.70.020 to 0.0249, incl 0.51 to 0.639, incl 3 612 76.2 6 12.70.025 to 0.0299, incl 0.64 to 0.759, incl 312 612 88.9 6 12.70.030 to 0.0349, incl 0.76 to 0.889, incl 4 612 101.6 6

41、12.70.035 to 0.0449, incl 0.89 to 1.139, incl 412 612 114.3 6 12.70.045 to 0.100, incl 1.14 to 2.54, incl 5 612 127.0 6 12.7B1060838.6 Remeasure and record the temperature measurements asdescribed in 6.4. If significant discrepancies of temperature orits distribution are found, correct them and agai

42、n measure andrecord the deflection.8.7 After having secured satisfactory temperature measure-ments and corresponding deflection data, establish the nextchosen temperature and follow the preceding routine over theagreed upon range of temperatures.8.8 In all cases, make a final set of measurements at

43、or nearroom temperature to determine whether or not there has beenpermanent distortion or any mechanical incident that wouldprevent determination of flexivity within the desired limits ofaccuracy. If such is evident, repeat the test under one of thefollowing conditions as agreed upon by the manufact

44、urer andthe purchaser.8.8.1 Test the same specimen over the same temperaturerange and over a different temperature range.8.8.2 Test another specimen over the same temperaturerange and over a different temperature range.9. Calculation9.1 For the calculation, see 3.1.2, Eq 1 and Eq 2.10. Report10.1 Th

45、e report shall include the following:10.1.1 Type of thermostat metal,10.1.2 Dimensions of specimen,10.1.3 Temperature and type of stabilizing heat treatment,10.1.4 Temperature range of test, and10.1.5 Flexivity.11. Precision and Bias11.1 Cumulative errors in the measurement of active length,temperat

46、ure, thickness, and deflection positions can producediscrepancies between flexivity determinations on the same testspecimen. Table 2 and Table 3 tabulate cumulative errors usinga statistical approach for various sample sizes, flexivities, andtemperature differences as percent at one standard deviati

47、on.Bias was not detected in round-robin measurements.TEST METHOD BSPIRAL COILS12. Apparatus12.1 This test method shall be conducted in accordance withTest Method B 389.TABLE 2 Cumulative Errors in Flexivity Determination of Flat Strips (Test Method A)NOTE 1 Interpolate for values not given in Table

48、2.Flexivity tQOne Standard Deviation Error in Flexivity, 6 %in./in.F (mm/mmC) in. (mm) in. (mm) DT = 100F(55.5F)DT = 200F(111.0C)DT = 300F(166.5C)High flexivity samples typically21 3 106(37.8 3 106) 0.100 (2.54) 5 (127.0) 0.82 0.44 0.320.090 (2.29) 5 (127.0) 0.80 0.43 0.320.080 (2.03) 5 (127.0) 0.79

49、 0.43 0.320.070 (1.78) 5 (127.0) 0.78 0.43 0.320.060 (1.52) 5 (127.0) 0.78 0.43 0.340.050 (1.27) 5 (127.0) 0.77 0.44 0.350.040 (1.02) 412 (114.3) 0.79 0.47 0.380.030 (0.76) 4 (101.6) 0.82 0.52 0.450.020 (0.51) 3 (76.2) 0.92 0.66 0.610.015 (0.38) 212 (63.5) 1.04 0.81 0.770.012 (0.30) 2 (50.8) 1.18 0.98 0.94Medium flexivity samples typically15 3 106(27 3 106) 0.100 (2.54) 5 (127.0) 1.01 0.52 0.370.090 (2.29) 5 (127.0) 0.96 0.50 0.360.080 (2.03) 5 (127.0) 0.92 0.49 0.360.070 (1.78) 5 (127.0) 0.88 0.47 0.350.060 (1.52) 5 (127.0) 0.85 0.47 0.360.050 (