1、Designation: B106 08 (Reapproved 2013)Standard Test Methods forFlexivity of Thermostat Metals1This standard is issued under the fixed designation B106; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A nu
2、mber in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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
3、 thermostat metals.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 parenthese
4、s 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 theresponsibility of the user of this standard to become familiarwith all ha
5、zards including 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 St
6、andards:2B389 Test Method for Thermal Deflection Rate of Spiral andHelical 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
7、 the radiusof 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
8、between any two temperatures,T1and T2, it is necessary to measure the curvature 1/R1and1/R2at temperature T1and T2, respectively. To find the cur-vature at either temperature (Fig. 1 and Fig. 2), measure thedistance D. The curvature is given by the following equa-tion:1/R 5 8D/Q214Dt14D2! (2)where:R
9、 = radius of 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 supported beam), = perpen-dicular distance between the longitudinal center lines ofthe lower surfac
10、e of the specimen midway between thepoint supports and the straight line joining the supportpoints, 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, dimens
11、ions ofspecimen, 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 wi
12、th two conical 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
13、 points of contact shall be horizontal.The specimen carrier and supports shall hold the specimenwithout constraint so that the curvature, due to its deflection,1These test methods are under the jurisdiction of ASTM Committee B02 onNonferrous Metals and Alloys and are the direct responsibility of Sub
14、committeeB02.10 on Thermostat Metals and Electrical Resistance Heating Materials.Current edition approved Aug. 1, 2013. Published August 2013. Originallyapproved in 1984. Last previous edition approved in 2008 as B106 08. DOI:10.1520/B0106-08R13.2For referenced ASTM standards, visit the ASTM website
15、, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1w
16、ill follow a vertical plane passing through the line joining thepoints of contact between specimen and supports. Suitablemeans shall be used to ensure test length.5.2 Micrometertraveling microscope, or equivalentdevice, so connected to the specimen carrier that expansionduring heating of the carrier
17、 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-sure in which the specimen carrier, together with adjustableelectric heating source is placed. The specimen needs to bemaintained at
18、 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 Temperature Measuring Apparatus, of such accuracythat the individual temperatures shall be known to within60.5F (0.3C).5.5 Deflection
19、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 joining the points of support. Such means may comprise atransmission rod disposed with its axis vertical and terminatingin a poin
20、t 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 is free to move in the direction of its axis. Therod shall bear at its free end an index suitable for microscopicalobservation, o
21、r else an electrical contact with which a microm-eter will permit the changes of the deflection of specimen to beaccurately observed. Alternatively, the deflection of the mid-point of the specimen may be directly observed by opticalmeans whose line of sight is horizontal and passes through thevertic
22、al line through the midpoint of the specimen. A microm-eter screw with extended spindle making direct contact withthe specimen may be used. In this case, electrical means shallbe provided that will indicate contact without significantdisturbance of the specimen. The measurement of the positionof the
23、 midpoint of the test specimen shall be of such accuracythat the individual positions at the test temperatures shall beknown to within 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 deflecti
24、on 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 errors i
25、n 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 low co
26、efficient 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 initial irregularity of curvature.6.2 The maximum thickness shall not be greater than theminimum thickness by more than 1 % of
27、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 bears the
28、 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 microm-eter or an equivalent method.6.5.1 For specimens less than 0.050 in. (
29、1.27 mm) inthickness, special precautions are necessary, such as the use of3Invar is a registered trademark of CRS Holding, a subsidiary of CarpenterTechnologies.FIG. 1 Test for Flexivity of Thermostat MetalsFIG. 2 Typical Apparatus DesignB106 08 (2013)2a micrometer reading directly to 0.0001 in. (0
30、.002 mm).Suitable optical methods may also be used.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 densityin grams
31、 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 asthat of the balance room to avoid errors due to convectioncurrents. For the accuracy required, no corrections are neces-sar
32、y 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 thepresence of grease or other films on the surface of the water. Tothis end it is recommended that after a preliminary c
33、leaning 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 water, beforeimmersing in the water to be used for weighing.7. Preparation of Test Specimen7.1 After being roughly cut o
34、r 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 each edge of the specimen, toeliminate material damaged by preliminary shaping. Slit edgeswith a minimum of burr may als
35、o 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 therelative locations of the reference marks. Do not use centerpunches or similar means because of the distortion produ
36、ced.7.3 It is recommended that the grain run along the length ofthe specimen.8. Procedure8.1 StabilizationAfter all preparatory work has beencompleted, subject the test specimen to a stabilizing heattreatment to relieve internal stresses. This treatment mayconsist of heating the specimen, while free
37、 to bend, for aprescribed time and temperature. The details of the stabilizingprocedure will depend upon the characteristics of the thermo-stat metal being tested and shall be as mutually agreed uponbetween the manufacturer and the purchaser.8.2 Test RoutineMount the specimen on the support on thesp
38、ecimen table. With the transmission rod in place take a zeroreading at room temperature.Apply slight mechanical pressureand then remove the rod at a point near the center of thespecimen. If appreciable zero shift is apparent with repeatedapplications of pressure, determine the cause and correctbefor
39、e proceeding with the test.FIG. 3 Width of Test SpecimenTABLE 1 Gage Length of Test Specimen (Test Method A)Specimen Thickness Gage Lengthin. mm in. mm0.015 to 0.0199, incl 0.38 to 0.509, incl 212 12 63.5 12.70.020 to 0.0249, incl 0.51 to 0.639, incl 3 12 76.2 12.70.025 to 0.0299, incl 0.64 to 0.759
40、, incl 312 12 88.9 12.70.030 to 0.0349, incl 0.76 to 0.889, incl 4 12 101.6 12.70.035 to 0.0449, incl 0.89 to 1.139, incl 412 12 114.3 12.70.045 to 0.100, incl 1.14 to 2.54, incl 5 12 127.0 12.7B106 08 (2013)38.3 When satisfactory initial conditions have beenestablished, make observations of deflect
41、ion and temperature atlow temperature and record the results.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.8.
42、6 Remeasure and record the temperature measurements asdescribed 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,
43、 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 or nearroom temperature to determine whether or not there has beenpermanent distortion or any mechanical incident that wouldprevent d
44、etermination of flexivity within the desired limits ofaccuracy. 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 a
45、nother 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 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 sta
46、bilizing 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,temperature, thickness, and deflection positions can producediscrepancies between flexivity determinations on the same testspecimen. Table 2
47、and Table 3 tabulate cumulative errors usinga statistical approach for various sample sizes, flexivities, andtemperature differences as percent at one standard deviation.Bias was not detected in round-robin measurements.TABLE 2 Cumulative Errors in Flexivity Determination of Flat Strips (Test Method
48、 A)NOTE 1Interpolate for values not given in Table 2.Flexivity tQOne Standard Deviation Error in Flexivity, %in./in.F (mm/mmC) in. (mm) in. (mm) T = 100F(55.5C)T = 200F(111.0C)T = 300F(166.5C)High flexivity samples typically21106(37.8 106) 0.100 (2.54) 5 (127.0) 0.82 0.44 0.320.090 (2.29) 5 (127.0)
49、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 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 typically15106(27106) 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
