1、 ISO 2013 Method for evaluation of tensile properties of metallic superplastic materials Mthode de dtermination des caractristiques de traction des matriaux mtalliques superplastiques INTERNATIONAL STANDARD ISO 20032 Second edition 2013-08-01 Reference number ISO 20032:2013(E) ISO 20032:2013(E)ii IS
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4、ished in Switzerland ISO 20032:2013(E) ISO 2013 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 S ymbols, t erms and definitions . 1 4 Principle 3 5 Test piece 4 6 Apparatus . 5 6.1 Testing machine . 5 6.2 Clamping device for test pieces 5 6.3
5、Heating apparatus 5 6.4 Atmosphere 5 6.5 Thermometric apparatus . 5 7 Procedure. 6 7.1 General . 6 7.2 Method for clamping the test piece . 6 7.3 Measurement of the test temperature 6 7.4 Application of the force . 6 7.5 Method for dimensional measurement of test pieces . 6 7.6 Method for determinin
6、g the superplastic elongation . 6 7.7 Determination of strain rate sensitivity exponent (m-value) . 7 7.8 Determination of the m-value with the R-type test piece 8 8 Test report 10 ISO 20032:2013(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of nation
7、al 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 subject for which a technical committee has been established has the right to be represented on that committee. Internatio
8、nal organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The procedures used to develop this document and those intended
9、 for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2. www.iso.org
10、/directives 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 held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in
11、 the Introduction and/or on the ISO list of patent declarations received. www.iso.org/patents Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement. The committee responsible for this document is ISO/TC 164, Mechanical testing o
12、f metals, Subcommittee SC 2, Ductility testing. This second edition cancels and replaces the first edition (ISO 20032:2007) of which it constitutes a minor revision.iv ISO 2013 All rights reserved ISO 20032:2013(E) Introduction Superplastic forming requires the characterization of metallic superplas
13、tic materials. The tensile test specified in this International Standard permits the evaluation of superplastic properties, such as superplastic elongation, flow stress, strain rate sensitivity exponent (m-value), stress-strain relation and flow stress-strain rate relation. ISO 2013 All rights reser
14、ved v Method for evaluation of tensile properties of metallic superplastic materials 1 Scope This International Standard specifies a method for evaluating the tensile properties of metallic superplastic materials which exhibit what is called “Fine-Grained Superplasticity”, without significant work-h
15、ardening 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 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensabl
16、e for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 6892-1, Metallic materials Tensile testing Part 1: Method of test at room temperature ISO 6892-2, Metallic materi
17、als Tensile testing Part 2: Method of test at elevated temperature ISO 7500-1, Metallic materials Verification of static uniaxial testing machines Part 1: Tension/compression testing machines Verification and calibration of the force-measuring system ISO 80000-1, Quantities and units Part 1: General
18、 IEC 60584-1, Thermocouples Part 1: Reference tables IEC 60584-2, Thermocouples Part 2: Tolerances 3 S ymbols , t erms and definitions For the purposes of this document, the symbols, terms and definitions given in Table 1 apply. INTERNATIONAL ST ANDARD ISO 20032:2013(E) ISO 2013 All rights reserved
19、1 ISO 20032:2013(E) T a b l e 1 S y m b o l s , t e r m s a n d d e f i n i t i o n sSymbol Term D e f i n i t ion Unit Superplasticity Superplastic state Deformation conditions on onset of superplasticity and its continuation Test piece R-type test piece Test piece that has the shape of a conventio
20、nal ten- sile test piece without its parallel portion R portion Principal portion of the R-type test piece to be elon- gated, which has an arc-like shape between gripsb Width of parallel-sided por- tion or minimum width of the R portion Original width of parallel-sided portion of the S-type test pie
21、ce or original minimum width of the R portion of the R-type test piecemmb o i Original width in division, i, of the R portion Original width in a specific division, i, of the R por- tionmmbi Width in division, i, of the R portion Width in a specific division, i, of the R portion after the interrupte
22、d testmmA Superplastic elongation Elongation after fracture in a superplastic state %B g Grip portion width Width of grip portion of the S- or R-type test piece mmL o Original gauge length Original distance between gauge marks measured by appropriate apparatus with an accuracy of at least 1 % of the
23、 distance or 0,01 mm, whichever is greatermmL u 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 fracture surface is on a single straight linemmL c Parallel length Original
24、 length of parallel portion of the S-type test piecemmL t Total length of test piece Original total length of test piece mmL g Grip portion length Length of grip portion of test piece mmL R R portion length Original length of the R portion mmL R Elongation of the R portion Increase in the R portion
25、length at any moment dur- ing the testmmR 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 piecemmS o Original cross-sectional area of test piece in the reduced section Original cross-sectional area of a test pie
26、ce meas- ured by an appropriate apparatus with an accuracy of 2 % or bettermm 2S o i Original cross-sectional area in division, i, of the R portion Original cross-sectional area in a specific division, i, of the R portionmm 2Si Cross-sectional area in divi- sion, i, of the R portion Cross-sectional
27、area in a specific division, i, of the R portion after the interrupted testmm 2t Thickness of test piece Thickness of the S- or R-type test piece mmt o i Original thickness in divi- sion, i, of the R portion Original thickness in a specific division, i, of the R portionmm2 ISO 2013 All rights reserv
28、ed ISO 20032:2013(E)Symbol Term D e f i n i t ion Unitti Thickness in division, i, of the R portion Thickness in a specific division, i, of the R portion after the interrupted testmm ForceF 10 10 % deformation force Force at 10 % nominal strain N StressK K value A constant-with-stress dimension, whi
29、ch is defined by Formula (5)MPa 10 10 % flow stress True stress when 10 % nominal strain is achieved MPa 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 defin
30、ed for the R-type test pieceMPai True stress A load during deformation divided by the cross-sec- tional area in a specific division, i, of the R portion, which is defined for the R-type test pieceMPa Straini True strain True strain given by deformation in a specific divi- sion, i, of the R portion P
31、eriod inter Period required for inter- rupted test Period required from the time when the axial force starts to increase linearly against strain in the elastic deformation stage, until elongation of the R portion, L R , reaches 3 mms Strain rate and m-value N Nominal strain rate Crosshead velocity d
32、ivided by the original paral- lel length, L cfor the S-type test piece, and divided by the original gauge length, L ofor the R-type test pieces 1 True strain rate Increment of true strain per unit time s 1 i True strain rate during deformation True strain rate during deformation in a specific divisi
33、on, i, of the R portions 1 m m-value Index representing the strain-rate sensitivity of flow stress in 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 ), f
34、 low s t ress ( f ) and strain-rate sensitivity exponent ( m-value). The tensile testing is carried out at elevated 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 li
35、mitation of furnace length, S-type test pieces are more suitable for lower-strain superplastic testing. R-type test 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.Table 1 (continued) ISO 2013 All ri
36、ghts reserved 3 ISO 20032:2013(E) 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 68
37、92-1. F i g u r e 1 S h a p e o f f l a t f o r m t e s t p i e c e ( S - t y p e ) Table 2 Dimensions of S-type test piece Dimensions in millimetres Gauge length Parallel length Width of parallel- sided portion R ad i u s of f i l le tL oL cb R18 24 6 Not more than 3 The recommended value should be
38、 as follows: L t= 2L g+ L c+ 2R (1) B g= 3b (2) The thickness of the test piece is the same as that of the material to be used. Figure 2 Shape of R-type test piece4 ISO 2013 All rights reserved ISO 20032:2013(E) Table 3 Dimensions of R-type test piece Dimensions in millimetresGrip portion width Mini
39、mum width of the R portion R portion length R portion radius Gauge lengthB gb L RR L o16 6 30 25 6L gshould 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 testing machine used shall conform to ISO 7500-1. Th
40、e 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 plastically deformed during an elevated temperatur
41、e test. A recommended method is described in 7.2. 6.3 Heating apparatus A furnace with a temperature-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
42、range of Table 4. Table 4 Allowable range of test temperatures Temperatures in kelvins Test temperature473 4738738731 0731 0731 2731 273 Allowable rangeAgreed by interested parties3 4 5 Agreed by interested parties 6.4 Atmosphere The measurement of the test piece dimensions, especially distances bet
43、ween gauge marks or divisions after the test, shall be enabled and 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
44、General The thermometric apparatus consists of a measuring device and a thermocouple. ISO 2013 All rights reserved 5 ISO 20032:2013(E) 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 ent
45、ire range of the temperature to be measured. 6.5.3 Thermocouple The thermocouple shall basically conform to IEC 60584-1 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 o
46、ther than a thermocouple is used, it shall be as accurate as or more accurate than a thermocouple. 7 Procedure 7.1 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 6892-1 and ISO 6892-2. 7.2 Method for clamping the t
47、est piece The test piece shall be clamped so that only axial force is applied to the test piece during the test. No axial compression and only a small (5 % of the 10 ) axial tension shall be applied to the clamped test piece to maintain straightness during heating to the specified temperature and ho
48、lding at this temperature before testing. 7.3 Measurement of the test temperature The measurement of the test temperature shall be conducted by using thermocouples as defined in 6.5.3. The temperature to be measured should be that of the test piece. Such measurement may be flexible if the correlativ
49、e temperature between the surface of the test piece and a certain position in the furnace was initially evaluated. For more precise temperature measurement, at least two thermocouples should be used at separate locations. Interested parties shall agree on the time of heating the test piece to the test temperature and the holding time at the test temperature before starting the test, provided that such agr
