1、Designation: B 106 96 (Reapproved 2002)e1Standard 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.
2、A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEParagraph 1.3 was corrected editorially in June 2002.1. Scope1.1 These test methods cover the determination of flexivity(a measure of ther
3、mal deflection rate or deflection temperaturecharacteristics) of thermostat metals.1.1.1 Test Method ATested in the form of flat strip 0.012in. (0.30 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 uni
4、ts are to be regardedas the standard. The values given in parentheses are providedfor information purposes only.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 ha
5、zards including those identified in the appropriateMaterial Safety Data Sheet for this product/material as pro-vided by the manufacturer, to establish appropriate safety andhealth practices, and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standar
6、ds:B 389 Test Method for Thermal Deflection Rate of Spiraland Helical Coils of Thermostat Metal23. Terminology3.1 Definitions:3.1.1 thermostat metala composite material in the form ofsheet or strip comprising two or more metallic layers ofdiffering coefficients of thermal expansion, such that the ra
7、diusof curvature of the composite changes with temperaturechange.3.1.2 flexivity (F)the change of curvature of the longitu-dinal 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 an
8、y two 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 8 D/Q21 4Dt 1 4D2! (2)where:R = rad
9、ius of curvature of the longitudinal center line ofthe specimen, 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 t
10、he specimenmidway 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 o
11、fspecimen, and the relative movement of the specimen. Thesimple beam method is the method for certification. Any use ofthe spiral coil method (Method B) is to be mutually agreedupon between the user and supplier.TEST METHOD AFLAT STRIPS5. Apparatus5.1 Specimen Carrier, provided with two conical supp
12、ortsfor 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)1These test methods are under the jurisdiction of ASTM Committee B02 onNonferrous Metals and Alloys and is
13、 the direct responsibility of SubcommitteeB02.10 on Thermostat Metal and Electrical Resistance Heating Materials.Current edition approved Jan. 10, 1996. Published April 1996. Originallypublished as B 106 84. Last previous edition B 106 90.2Annual Book of ASTM Standards, Vol 02.04.1Copyright ASTM Int
14、ernational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.shall be known to within 60.005 in. (0.13 mm), and the line ofplane passing through the points of contact shall be horizontal.The specimen carrier and supports shall hold the specimenwithout constraint so
15、 that the curvature, due to its deflection,will follow a vertical plane passing through the line joining thepoints of contact between specimen and supports.5.2 Micrometertraveling microscope, or equivalent de-vice, so connected to the specimen carrier that expansionduring heating of the carrier or c
16、onnecting parts will not causeappreciable displacement of the measuring device with respectto the supports.5.3 BathA stirred liquid bath or uniformly heated enclo-sure in which the specimen carrier, together with adjustableelectric heating source is placed. The specimen needs to bemaintained at the
17、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 Temperature Measuring Apparatus, of such accuracythat the individual temperatures shall be known to within60.5F (0.3C).5.5 Deflection Index
18、Means 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 joining the points of support. Such means may comprise afused-quartz transmission rod disposed with its axis verticaland terminating i
19、n a point or knife-edge, which shall engagethe specimen midway between the points of contact with thesupports.5.5.1 The transmission rod shall be mounted in such amanner that it is free to move in the direction of its axis. Therod shall bear at its free end an index suitable for microscopicalobserva
20、tion, 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 themidpoint of the specimen may be directly observed by opticalmeans whose line of sight is horizontal and passes through thev
21、ertical line through the midpoint of the specimen. A microme-ter screw with extended spindle making direct contact with thespecimen may be used. In this case, electrical means shall beprovided that will indicate contact without significant distur-bance of the specimen. The measurement of the positio
22、n 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 transmission rod is used, it and any attached partsshall be of such weight or so counterweighted that they will notcause a d
23、eflection 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. Concentrated loading at the center of the specimenwill cause the curvature to be other than circular and may causesignificant e
24、rrors 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 ofthe micrometer, to within 60.002 in. (0.05 mm).5.6 All metallic components of the flexivity apparatusshould be made of very
25、 low coefficient of thermal expansioncomponents. The recommended material is invar.6. Test Specimens6.1 The test specimen shall be in the form of a strip thatdisplays no apparent initial irregularity of curvature.6.2 The maximum thickness shall not be greater than theminimum thickness by more than 1
26、 % 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 the minimum width bymore than 2 % of the latter.6.4 The length shall be such as to allow a distance betweensupports that bea
27、rs 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 determinedwithin 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
28、 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.FIG. 1 Test for Flexivity of Thermostat MetalsFIG. 2 Typical Apparatus DesignB 10626.5.2 The average thickness may be calc
29、ulated 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 densityin grams per cubic centimetre is equivalent to the weight in airdivided by the loss of weight due
30、to submergence in water. Thetemperature of the water shall be approximately the same asthat 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 e
31、xercised to remove all air bubblesfrom the sample when weighing it in water and to avoid thepresence 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 su
32、spending it while weighing and thoroughlyrinsed, first in ether, then alcohol and finally 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.
33、Remove the amount of material extending a distance not lessthan twice the thickness along 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 mar
34、ks (by such means as a sharp drill,scribing tool, or milling cutter). Determine and record 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
35、.1 StabilizationAfter all preparatory work has been com-pleted, subject the test specimen 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
36、 willdepend upon the characteristics of the thermostat metal beingtested and shall be as mutually 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. A
37、pply slight mechanicalpressure and then remove the rod at a point near the center ofthe specimen. 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-lishe
38、d, make observations of deflection and temperature atroom temperature and record the results.FIG. 3 Width of Test SpecimenTABLE 1 Gage Length of Test Specimen (Test Method A)Specimen Thickness Gage Lengthin. mm in. mm0.012 to 0.0149, incl 0.30 to 0.379, incl 2 612 50.8 6 12.70.015 to 0.0199, incl 0.
39、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 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
40、1.14 to 2.54, incl 5 612 127.0 6 12.7B 10638.4 Adjust the temperature of the specimen to the next valuedesired. Measure and record the temperature of the specimen atpoints on or near the center and ends.8.5 Measure and record the deflection.8.6 Remeasure and record the temperature measurements asdes
41、cribed in 6.4. If significant discrepancies of temperature orits distribution are found, correct them and again measure andrecord the deflection.8.7 After having secured satisfactory temperature measure-ments and corresponding deflection data, establish the nextchosen temperature and follow the prec
42、eding routine over theagreed upon range of temperatures.8.8 In all cases, make a final set of measurements at 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 ofacc
43、uracy. If such is evident, repeat the test under one of thefollowing conditions as agreed upon by the manufacturer 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
44、 different temperature range.9. Calculation9.1 For the calculation, see 3.1.2, Eq 1 and Eq 2.10. Report10.1 The 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,
45、 and10.1.5 Flexivity.11. Precision and Bias11.1 Cumulative errors in the measurement of active length,temperature, thickness, and deflection positions can producediscrepancies between flexivity determinations on the same testspecimen. Table 2 and Table 3 tabulate cumulative errors usinga statistical
46、 approach for various sample sizes, flexivities, andTABLE 2 Cumulative Errors in Flexivity Determination of Flat Strips (Test Method A)NOTE 1 Interpolate for values not given in Table 2.Flexivity tQOne Standard Deviation Error in Flexivity, 6 %in./in.F (mm/mmC) in. (mm) in. (mm) DT = 100F(55.5F)DT =
47、 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 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
48、 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
49、.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 (1.27) 5 (127.0) 0.83 0.46 0.360.040 (1.02) 412 (114.3) 0.84 0.49 0.400.030 (0.76) 4 (101.6) 0.87 0.54 0.460.020 (0.51) 3 (76.2) 0.98 0.68 0.620.015 (0.38) 212 (63.5) 1.10 0.83 0.770.012 (0.30) 2 (50.8) 1.26 1.00 0.95Low flexivity samples typically7 3 106(12.6 3 106) 0.100 (2.54) 5 (127.0) 1.48 0.76 0.520.090 (2.29) 5 (127.0) 1.37 0.70 0.490.080 (2.03) 5 (127.0) 1.27 0.65 0.460.070 (1.78) 5 (127.0) 1.17 0.61
