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1、BRITISH STANDARD BS ISO 20032:2007 Method for evaluation of tensile properties of metallic superplastic materials ICS 77.040.10 ? Licensed Copy: London South Bank University, London South Bank University, Sat Mar 17 03:53:27 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS ISO 20032:2007 This British S
2、tandard was published under the authority of the Standards Policy and Strategy Committee on 30 March 2007 BSI 2007 ISBN 978 0 580 50332 0 National foreword This British Standard was published by BSI. It is the UK implementation of ISO 20032:2007. The UK participation in its preparation was entrusted
3、 by Technical Committee ISE/NFE/4, Mechanical testing of metals, to Subcommittee ISE/NFE/4/1, Uniaxial testing of metals. A list of organizations represented on ISE/NFE/4/1 can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a con
4、tract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendments issued since publication Amd. No. DateComments Licensed Copy: London South Bank University, London South Bank University, Sat Mar 17 03:53:27 GMT+00:
5、00 2007, Uncontrolled Copy, (c) BSI Reference number ISO 20032:2007(E) INTERNATIONAL STANDARD ISO 20032 First edition 2007-02-15 Method for evaluation of tensile properties of metallic superplastic materials Mthode de dtermination des caractristiques de traction des matriaux mtalliques superplastiqu
6、es BS ISO 20032:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Mar 17 03:53:27 GMT+00:00 2007, Uncontrolled Copy, (c) BSI ii Licensed Copy: London South Bank University, London South Bank University, Sat Mar 17 03:53:27 GMT+00:00 2007, Uncontrolled Copy, (c) BSI
7、iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references. 1 3 Symbols, terms and definitions 1 4 Principle. 3 5 Test piece 4 6 Apparatus 5 7 Procedure 6 8 Test report . 10 BS ISO 20032:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Mar 17 0
8、3:53:27 GMT+00:00 2007, Uncontrolled Copy, (c) BSI iv 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.
9、Each member body interested in a subject 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 Internat
10、ional Electrotechnical Commission (IEC) 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 Stand
11、ards adopted by the technical committees 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 subjec
12、t of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 20032 was prepared by Technical Committee ISO/TC 164, Mechanical testing of metals, Subcommittee SC 2, Ductility testing. BS ISO 20032:2007 Licensed Copy: London South Bank University, London Sou
13、th Bank University, Sat Mar 17 03:53:27 GMT+00:00 2007, Uncontrolled Copy, (c) BSI v Introduction Superplastic forming requires the characterization of metallic superplastic materials. The tensile test specified in this International Standard permits the evaluation of superplastic properties, such a
14、s superplastic elongation, flow stress, strain-rate sensitivity exponent (m-value), stress-strain relation and flow stress-strain-rate relation. BS ISO 20032:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Mar 17 03:53:27 GMT+00:00 2007, Uncontrolled Copy, (c) BSI
15、 blank Licensed Copy: London South Bank University, London South Bank University, Sat Mar 17 03:53:27 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 1 Method for evaluation of tensile properties of metallic superplastic materials 1 Scope This International Standard specifies a method for evaluating the
16、tensile properties of metallic superplastic materials which exhibit fine-grained superplasticity, without significant work-hardening or dynamic microstructure evolution, by means of a tensile test at constant cross-head velocity, for flat-form test pieces, without an extensometer attached. 2 Normati
17、ve references The following referenced documents are indispensable for the 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 31-0, Quantities and units Part
18、 0: General principles ISO 783, Metallic materials Tensile testing at elevated temperature ISO 6892, Metallic materials Tensile testing at ambient temperature ISO 7500-1, Metallic materials Verification of static uniaxial testing machines Part 1: Tension/compression testing machines Verification and
19、 calibration of the force-measuring system IEC 60584-1, Thermocouples Part 1: Reference tables IEC 60584-2, Thermocouples Part 2: Tolerances 3 Symbols, terms and definitions For the purposes of this document, the symbols, terms and definitions given in Table 1 apply. BS ISO 20032:2007 Licensed Copy:
20、 London South Bank University, London South Bank University, Sat Mar 17 03:53:27 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 2 Table 1 Symbols, terms and definitions Symbol Term Definition Unit Superplasticity Superplastic state Deformation conditions on onset of superplasticity and its continuation
21、Test piece R-type test piece Test piece that has the shape of a conventional tensile test piece without its parallel portion R portion Principal portion of the R-type test piece to be elongated, which has an arc-like shape between grips b Width of parallel-sided portion or minimum width of the R por
22、tion Original width of parallel-sided portion of the S-type test piece or original minimum width of the R portion of the R-type test piece mm boi Original width in division, i, of the R portion Original width in a specific division, i, of the R portion mm bi Width in division, i, of the R portion Wi
23、dth in a specific division, i, of the R portion after the interrupted test mm A Superplastic elongation Elongation at fracture in a superplastic state % Bg Grip portion width Width of grip portion of the S- or R-type test piece mm Lo Original gauge length Original distance between gauge marks measur
24、ed by appropriate apparatus with an accuracy of at least 1 % of the distance or 0,01 mm, whichever is greater mm Lu Final gauge length after fracture Final distance between gauge marks measured after fracture with fracture surfaces placed together with care, so that the centre line of either fractur
25、e surface is on a single straight line mm Lc Parallel length Original length of parallel portion of the S-type test piece mm Lt Total length of test piece Original total length of test piece mm Lg Grip portion length Length of grip portion of test piece mm LR R portion length Original length of the
26、R portion mm LR Elongation of the R portion Increase in the R portion length at any moment during the test mm R Radius of fillet or R portion radius Original radius of fillet of the S-type test pieces or original R portion radius of the R-type test piece mm So Original cross-sectional area of test p
27、iece in the reduced section Original cross-sectional area of a test piece measured by an appropriate apparatus with an accuracy not more than 2 % mm2 Soi Original cross-sectional area in division, i, of the R portion Original cross-sectional area in a specific division, i, of the R portion mm2 Si Cr
28、oss-sectional area in division, i, of the R portion Cross-sectional area in a specific division, i, of the R portion after the interrupted test mm2 t Thickness of test piece Thickness of the S- or R-type test piece mm t0i Original thickness in division, i, of the R portion Original thickness in a sp
29、ecific division, i, of the R portion mm ti Thickness in division, i, of the R portion Thickness in a specific division, i, of the R portion after the interrupted test mm BS ISO 20032:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Mar 17 03:53:27 GMT+00:00 2007, U
30、ncontrolled Copy, (c) BSI 3 Table 1 (continued) Symbol Term Definition Unit Force F10 10 % deformation force Force at 10 % nominal strain N Stress K K value A constant-with-stress dimension, which is defined by Equation (1) MPa 10 10 % flow stress True stress when 10 % nominal strain is achieved MPa
31、 f Flow stress True stress during superplastic deformation MPa N Nominal stress A load during deformation divided by the minimum area of the original cross-section in the R portion, which is defined for the R-type test piece MPa i True stress A load during deformation divided by the cross-sectional
32、area in a specific division, i, of the R portion, which is defined for the R-type test piece MPa Strain i True strain True strain given by deformation in a specific division, i, of the R portion s1 Period inter Period required for interrupted test Period required from the time when the axial force s
33、tarts to increase linearly against strain in the elastic deformation stage, until elongation of the R portion, LR, reaches 3 mm s Strain rate and m-value N ? Nominal strain rate Crosshead velocity divided by the original parallel length, Lc for the S-type test piece, and divided by the original gaug
34、e length, Lo for the R-type test piece s1 ? True strain rate Increment of true strain per unit time s1 i? True strain rate during deformation True strain rate during deformation in a specific division, i, of the R portion s1 m m-value Index representing the strain-rate sensitivity of flow stress in
35、superplastic materials 4 Principle The test consists of straining a test piece by a tensile force, for the purpose of determining the superplastic properties, such as superplastic elongation (A), flow stress and strain-rate sensitivity exponent (m-value). The tensile testing is carried out at elevat
36、ed temperatures and strain rates. An S-type test piece is employed to evaluate mechanical properties for general superplastic materials, or at an early stage of deformation. Due to the limitation of furnace length, S-type test pieces are more suitable for lower-strain superplastic testing. R-type te
37、st pieces are more suitable for higher-strain superplastic testing, as most of the strain is developed in a small section at the centre of the specimen. BS ISO 20032:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Mar 17 03:53:27 GMT+00:00 2007, Uncontrolled Copy,
38、 (c) BSI 4 5 Test piece The shape and dimensions are given in Figures 1 and 2, and Tables 2 and 3, respectively. The thickness of a test piece shall be the same as the sheet thickness of the material. The dimensional tolerance of a test piece shall be in accordance with ISO 6892. Figure 1 Shape of f
39、lat form test piece (S-type) Table 2 Dimensions of S-type test piece Dimensions in millimetres Gauge length Parallel length Width of parallel- sided portion Radius of fillet Lo Lc b R 18 24 6 Not more than 3 The recommended value should be as follows: Lt = 2Lg + Lc + 2R (1) Bg = 3b (2) The thickness
40、 of the test piece is the same as that of the material to be used. BS ISO 20032:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Mar 17 03:53:27 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 5 Figure 2 Shape of R-type test piece Table 3 Dimensions of R-type test piece
41、 Dimensions in millimetres Grip portion width Minimum width of the R portion R portion lengthR portion radius Gauge length Bg b LR R Lo 16 6 30 25 6 Lg should not be less than 20 mm. The thickness of the test piece is the same as that of the material to be used. 6 Apparatus 6.1 Testing machine The t
42、esting machine used shall conform to ISO 7500-1. The machine used shall satisfy the condition of constant cross-head velocity. The appropriate class of machine range shall be selected under the agreement between interested parties. 6.2 Clamping device for test pieces The clamping device shall not be
43、 plastically deformed during an elevated temperature test. A recommended method is described in 7.2. BS ISO 20032:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Mar 17 03:53:27 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 6 6.3 Heating apparatus A furnace with a te
44、mperature-regulator shall be used for heating the test pieces. During a test, the furnace shall be capable of keeping the test piece temperature over the gauge length uniform and constant within the allowable range of Table 4. Table 4 Allowable range of test temperatures Temperatures in kelvins Test
45、 temperature u u 473 473 u u 873 873 u u 1 073 1 073 u u 1 273 1 273 Allowable range Agreed by interested parties 3 4 5 Agreed by interested parties 6.4 Atmosphere The measurement of the test piece dimensions, especially distances between gauge marks or divisions after the test, shall be enabled and
46、 the damage of the device shall be avoided in the environment used. If the test is performed in a controlled atmosphere, the measured force should be corrected by compensating the pressure difference. 6.5 Thermometric apparatus 6.5.1 General The thermometric apparatus consists of a measuring device
47、and a thermocouple. 6.5.2 Measuring device The measuring device shall be capable of measuring the temperature of the test piece within the allowable range given in Table 4, over the entire range of the temperature to be measured. 6.5.3 Thermocouple The thermocouple shall basically conform to IEC 605
48、84-1 and IEC 60584-2. Also, the materials used for the thermocouple shall be capable of withstanding the service temperature and environment. When a temperature measurement instrument other than a thermocouple is used, it shall be as accurate as or more accurate than a thermocouple. 7 Procedure 7.1
49、General Test procedures are described in 7.2 to 7.8. Additions that are not described in this clause shall be in accordance with ISO 6892 and ISO 783. 7.2 Method for clamping the test piece The test piece shall be clamped so that only axial force is applied to the test piece during the test. No compressive or minimum tensile forces shall be applied to the clamped test piece during heating to the specified temperature and holdin