1、BRITISH STANDARDBS ISO 15490:2008Fine ceramics (advanced ceramics, advanced technical ceramics) Test method for tensile strength of monolithic ceramics at room temperature ICS 81.060.30g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55
2、g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS ISO 15490:2008This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 March 2008 BSI 2008ISBN 978 0 580 62549 7National forewordThis British Standard is the UK
3、 implementation of ISO 15490:2008. It supersedes BS ISO 15490:2000 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee RPI/13, Advanced technical ceramics.A list of organizations represented on this committee can be obtained on request to its secretary.Thi
4、s publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.Amendments/corrigenda issued since publicationDate CommentsReference numberISO 1549
5、0:2008(E)INTERNATIONAL STANDARD ISO15490Second edition2008-01-15Fine ceramics (advanced ceramics, advanced technical ceramics) Test method for tensile strength of monolithic ceramics at room temperature Cramiques techniques Mthode dessai de rsistance la traction des cramiques monolithiques tempratur
6、e ambiante BS ISO 15490:2008ii iiiContents Page Foreword iv 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principle. 2 5 Apparatus 2 6 Test specimen . 2 7 Procedures 3 8 Calculation. 5 9 Report 5 Annex A (informative) Shape and dimensions of test specimen 7 Bibliography . 10 BS
7、 ISO 15490:2008iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a sub
8、ject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (I
9、EC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical commit
10、tees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be
11、 held responsible for identifying any or all such patent rights. ISO 15490 was prepared by Technical Committee ISO/TC 206, Fine ceramics. This second edition cancels and replaces the first edition (ISO 15490:2000), which has been technically revised. BS ISO 15490:20081Fine ceramics (advanced ceramic
12、s, advanced technical ceramics) Test method for tensile strength of monolithic ceramics at room temperature 1 Scope This International Standard specifies the test method for determining the tensile strength under uniaxial loading of monolithic fine ceramics and whisker or particulate-reinforced cera
13、mic composites at room temperature. This test method, in which parasitic bending is minimized, may be used for material development, material comparison, quality assurance, characterization and design data generation. 2 Normative references The following referenced documents are indispensable for th
14、e application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 3611:1978, Micrometer callipers for external measurement ISO 7500-1:2004, Metallic materials Verificatio
15、n of static uniaxial testing machines Part 1: Tension/compression testing machines Verification and calibration of the force-measuring system 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 tensile stress value of tensile force applied to a t
16、est specimen divided by the original cross-sectional area of the gauge part of a test specimen 3.2 tensile strength maximum tensile stress applied to a test specimen during a tensile strength test 3.3 maximum tensile force maximum force applied to a test specimen during a tensile strength test 3.4 g
17、auge section parallel portion of the test specimen having the same cross-section as its middle part 3.5 gripped region end part of a test specimen which is held by the gripping device of a tensile test machine BS ISO 15490:20082 3.6 gripping device device to hold a test specimen and to transfer a fo
18、rce to a test specimen during a tensile test 3.7 bending strain component value of bending strain generated on the surface of the gauge part of a test specimen by axial misalignment, divided by the average strain 3.8 percent bending bending strain component times 100 3.9 strain fractional increase i
19、n length when a test specimen is loaded in tension 3.10 breaking force force at which fracture occurs 4 Principle The test consists of applying a tensile force to a test specimen by uniaxial loading until fracture, for the purpose of determining the tensile strength. 5 Apparatus 5.1 Tensile testing
20、machine The testing machine used for the tensile test shall conform to the requirements of lSO 7500-1:2004, Class 1. 5.2 Gripping devices Every endeavour shall be made to ensure that test specimens are held in such a way that the force is applied as axially as possible (see 7.2). For this purpose, v
21、arious types of gripping device may be used. NOTE The gripping devices that have been applied to measuring tensile strength of monolithic ceramics and their advantages/disadvantages are shown in ASTM C 1273. 6 Test specimen 6.1 Shape and dimensions The shape and dimensions of the test specimens depe
22、nd on several factors, including the purpose of the tensile test itself, the gripping devices, and the shape and dimensions of the ceramic products whose tensile strength is to be determined. Therefore, various shapes and dimensions may be used. The shapes and dimensions, however, shall be determine
23、d so that the tensile stress is applied uniformly in the gauge section (see 7.2). Also, it shall be ensured that stress concentrations which could lead to undesired fractures outside the gauge section are minimized. In addition, the cross-section of the gauge section shall be uniform, with a dimensi
24、onal accuracy greater than 0,5 %. The test specimens that have been applied to testing fine ceramics are shown in Annex A. BS ISO 15490:200836.2 Test specimen preparation Surface finishes in the gauge section of the order of average roughness Ra 0,2 m to 0,4 m (measured in the longitudinal direction
25、) are recommended in order to avoid surface-roughness-related fracture. Unless it is part of an exercise to determine the effects of grinding methods, it is highly recommended that the final grinding operation in the gauge section be performed along the longitudinal direction of the test specimen, i
26、n order to ensure that grinding marks are parallel to the applied tensile stress. Care shall be taken in storage and handling of finished test specimens to avoid the introduction of random and severe flaws. NOTE In some cases, the final surface finish might not be as important as the subsurface dama
27、ge produced during the grinding process. This damage is not readily observed or measured. 6.3 Number of test specimens As a general rule, a minimum of ten tests is required for the purpose of estimating a mean, and thirty or more tests are needed to estimate the strength distribution parameters, suc
28、h as Weibull modulus and characteristic strength Tests with fractures outside the gauge section shall not be included in the calculation of the mean or standard deviation, but may be included in the calculation of Weibull statistics as censored tests. NOTE The number of test specimens needed for the
29、 test depends on the precision required for estimating the parameters of strength properties. 7 Procedures 7.1 Test specimen dimensions The diameter or thickness and width of the gauge section of each test specimen shall be determined to within 0,02 mm. Measurements on at least three different cross
30、-sections in the gauge section shall be made. The average of the multiple measurements shall be used in calculating the cross-sectional area. 7.2 Axial alignment The testing system shall be verified using the following procedures. Three or four strain gauges are equally spaced around the circumferen
31、ces on two cross-sectional planes. The strain gauge planes shall be symmetrically located about the longitudinal midpoint of the gauge section, and shall be separated by at least 3/4 of the length of the gauge section. When the gauge section is not long enough to have two strain gauge planes, one pl
32、ane may be used. In this case, the location shall be the longitudinal midpoint of the gauge section. When axial strain gauges are mounted, the gauge axis shall be aligned with the stress axis, so that the deviation is less than 0,035 rad (2o). Ideally, the verification shall be made for all the indi
33、vidual test specimens to be tested. However, if this is not possible or desired, a permanent strain-gauged “dummy” test specimen may be used, provided that the test specimen to be tested has exactly the same shape as the “dummy” one. It is most preferable that it be of the same material as that to b
34、e tested. Mount the test specimen in the gripping device and apply a load so as to give an average strain of one half of that expected at fracture. Measure the amount of strain as a function of average strain, and calculate the percent bending using the following equation: BS ISO 15490:20084 221/213
35、 2 4123 4( ) ( ) 2 100B += +for four gauges and 222 1/212312233123()210B+ = +for three gauges, where B is the percentage bending; 1, 2, 3and 4are the strain readings for strain gauges. When alignment is verified for the individual test specimens, percentage bending shall not exceed 7,5 % at an avera
36、ge strain of one-half that expected at fracture. Alignment with a percentage bending of 5 % or less is required when the testing system is verified using a permanent strain-gauged “dummy” test specimen, since this will minimize the contribution of the testing system to percentage bending in the actu
37、al test specimens. This verification shall be made at least at the beginning and end of each test series. Verification is highly recommended for all the test specimens. Care shall be taken to avoid placing the strain gauges too near geometric transitions in the gauge section which can cause strain c
38、oncentration and inaccurate measurements of the strain in the uniform gauge section. NOTE Information on bending in tensile strength tests is available in ASTM C 1273-05, Annex. 7.3 Test mode and rates Various test modes, including force, displacement (of the test machine cross-head) and strain cont
39、rol may be used. Sufficiently rapid testing rates are recommended so that final fracture is reached in less than 10 s in order to minimize environmental effects and thus obtain the intrinsic value of the ultimate tensile strength. In the case of evaluating rate effects, lower rates can be used. In a
40、ll cases, the test mode and rate shall be reported. The most common test mode is displacement control. In this case, cross-head speeds greater than 0,008 33 mm/s (0,5 mm/min) are recommended. For force control, stress rates greater than 20 MPa/s are recommended. Generally, these conditions satisfy t
41、he above requirements if the testing assembly is sufficiently rigid during the last half of the duration of the test. 7.4 Recording After conducting the test, the breaking force shall be read to an accuracy of 1,0 % and noted for the report, and the fracture location shall be identified. If required
42、, examine the fracture surface with a microscope to determine the position and nature of the fracture origin. BS ISO 15490:200858 Calculation 8.1 Tensile strength The following formula shall be used for calculating the tensile strength for each test. mmFRA= where Rmis the tensile strength; Fmis the
43、maximum tensile force; A is the cross-sectional area. 8.2 Mean and standard deviation The mean and standard deviation for each test series shall be calculated as follows. imXXn=1/ 22m()SD1iXXn=where Xmis the mean deviation; Xiis the measured value; n is the number of valid tests; SD is the standard
44、deviation. 9 Report 9.1 Test set The following information shall be reported for each test set: a) shape and dimensions of test specimen; b) testing machine (in the case of a commercial testing machine, report the manufacturer and the model number); c) gripping device (in the case of a commercial gr
45、ipping device, report the manufacturer and the model number); d) number of test specimens tested in a valid fashion (fractured within the gauge section); e) total number of test specimens tested; BS ISO 15490:20086 f) all material data, including vintage data or billet identity data; g) test-specime
46、n-preparation procedure, including all stages of machining; h) heat treatments, or pre-test exposures, applied to the as-processed material or to the as-fabricated test specimen; i) test environment, including relative humidity, ambient temperature, and atmosphere (e.g. in air, nitrogen, vacuum, sil
47、icon oil, etc.); j) test mode (force, stress, displacement or strain control) and test rate (force, stress, displacement or strain rates); k) percentage bending and corresponding average strain measured in the axial alignment verification; l) the number of the strain gauges used for each of the veri
48、fications; m) mean tensile strength and standard deviation; n) strength distribution parameters (Weibull modulus and characteristic strength), if calculated; o) any significant deviations from the procedures and requirements of this International Standard. 9.2 Individual test specimen The following
49、information shall be reported for each specimen tested: a) pertinent overall test specimen dimensions, if measured; b) average cross-sectional dimensions of the gauge section; c) average surface roughness, if measured, of the gauge section measured in the longitudinal direction; d) breaking force; e) calculated tensile strength; f) fracture strain, if measured; g) force-strain curve, or force-time curve, if recorded; h) fracture location relative to the gauge-section midpoint (positive is toward the top of the test
