Asociaiia de Standardizare din Romanla, UPRUC GTR, 34/05/2018 iS 77,040.10 ape SRENI Breage t Ee STANDARD ROMAN Hale me Materiale metalice- incercarea la tractiune © L : Partea 1: Metoda de “incercare la temperatura = amblanta Metallic materials. Tensile tésting. Part 1: Method of test: at . room temperature - Matériaux métalliques: Essai. de traction. Partie 1: Méthode’ dessai 3 température ambiante 7 APROBARE Aprobat de Directorul General al ASRO la 20 ianuarie 2010 Standardul european EN {SO 6892-1:2009 a fost adoptat prin metoda notei de confirmare si are statutul unui standard roman Tnlocuieste SR EN 10002-1:2002 CORESPONDENTA Acest standard este identic cu standardul european... EN ISO 6892-1:2009 This standard is identical with the European Standard EN ISO 6892-1:2009 La présente norme est identique a la Norme européenne EN ISO 6892-1:2009 FSOCIATIA DE STANDARDIZARE DIN ROMANIA (ASRO) ‘Si. Mendiieey ny. 21-25, 000 010362, Bure Dreder Genera Tel: 4021 3163296, Fax ~4021 9160070 rca Sree TA.M0'21 310 1720x4021 S10 4909, 140211247 44, Fax a4021 35.8 iecks Pubkoab Sav. VereariAbenamente: Te $4021 31677 25 Fax 4021917 2514 4021 31294 08 Servo Retaxge vena Drop de Au 4021 E074 iM @AsRO Reproducerea sau utlizarea integral cau parata a prezeritll standard Tn oven pula Fr ovo Pepin (elchodte, mecanc, tocopiere,recrofimare ete.) est arisé ac mu ist acd srs at Ref.: SR EN 1SO 6892-1:2010 EditiatAsociatia de Standardizare din Romania, UPRUC CTR, 31/05/2010 EUROPEAN STANDARD EN ISO 6892-1 : NORME EUROPEENNE EUROPAISCHE NORM ‘August 2009 Ics 77,040.10 ‘Supersedes EN 10002-1:2001 English Version Metallic materials - Tensile testing - Part 1: Method of test at room temperature (ISO 6892-1:2009) atdciacx métaliques - Essai de tration - Paria t: Metalische Werkstoffe- Zugversuch - Tail: Profvertahren Neto dessal a empaytne ambit (SO 682 ‘bei Reurntemperaiur (ISO 6892-1:2009) 7 ‘This Europeen Standard was approved by CEN on 13 March 2008, ‘CEN members are bourd to comply withthe CENICENELEC intemal Regulations which stipulate the concitions forgiving thie European Standard tne situs oF @ rational sendard without any aeration. Up-to-date lite and bibliographical refacancos concaming such national ‘StaWards may be obleined on eppiicetion to the CEN Management Cartre orto any CEN member. “Thi European Standard exist in three ofl versions (English, French, German. A version in any other language made by translation Under the responsibly of CEN member Ino is own language and note tothe CEN Management Centre nas the same satus 65 the official versions. CEN members ere the national standards bodies of Austia, Belgium, Bugaria, Cyprus, Czoch Republic, Denmerk, Estonia, Finland, Fanos, Germany, Gresce, Hungary, lelend, keland, aly, Lata, Lthuania, Luxembourg, Mata, Netherands, Norway. Poland. Portugel. Romaria, Slovakia, Sloverve, Spain, Sweden, Svetzertand and United Kingdarr. a EUROPEAN COMMITTEE FOR STANDARDIZATION COMITE BUROPEEN DE NORMALISATION t EUROPAISCHES KOMITEE FUR NORMUNG Management Centre: Avenue Marnix 47, 8-1000 Brusacle ©2009 CEN Al ights of exploitation in any form and by any means reserved Rel No, EN ISO 6862-1:2000: E ‘worldvige for CEN national Members,EN ISO 6892-1:2009 (E) Page Contents | i rozisorit ‘azo onan ‘eeniow up ezenpuepueis ap enEI>OSY‘Asoctatia de Standardizare din Romania, UPRUC CTR, 31/08/2010 EN ISO 6892-1:2009 {E) Foreword “This document (EN ISO 6892-1:2009) has been prepared by Technical Committee ISO/TC 184 "Mechanical testing of metals” in collaboration with Technical Committee ECISS/TC 1 "Tensile testing” the secretariat of which is held by AFNOR. ‘This Europeen Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by February 2010, and conflicting national standards shall be withdrawn at the latest by February 2010. ‘Attention is drawn to the possibility that some of the elements of this document may be the subject of patent fights. CEN [andlor CENELEC] shall not be held responsible for identifying any or all such patent rights. ‘This document supersedes EN 10002-1:2001. ‘According to the CENICENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Waly, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, ‘Sweden, Switzerland and the United Kingdom. Endorsement notice “The text of 180 6892-1:2009 has been approved by CEN as a EN ISO 6892-1:2009 without any modification.Asociatia de Standardizare din Romania, UPRUC CTR, 31/05/2010 INTERNATIONAL Iso STANDARD 6892-1 First edition 2009-08-15 TS Metallic materials — Tensile testing — Part 1: Method of test at room temperature _ Metéraux métaliques — Essai de traction ~* Partie 1: Méthode d'essai a température ambiante Reference number 10 6802-1:2009(E) @180 2008do Standardizare din Romania, UPRUC CTR, 31/05/2010 Asoct 180 6892-1:2009(E) POF dlvclaimer “This POF fe may contain embedded typetaoss. In accordance with Adobe's icensing pai, this fle mey be printed or views But hall not be ected urless the lypafaoes which aro embedded are icensed to and matted on the computer performing the edting, In ‘SRenioadng tis fle, parbee accept therein the reeponstalty Of not nmnging Adobe's ensing poly. The 1SO Central Secretariat ‘caps no bly in his area. Adobe i a trademark of Adobe Systems Incorporated. DDetats of the software products uzed to ersat the PDF fle ean ba found inthe Genera info relative tothe file; the POF-creation Dorancters wee optinize fr pentng. Every care has bean taken to ensure thal the fle sutabl fr use by ISO member bodes. n {ra unkely event tat problem reating to tis found, please inform the Cental Secretariat atthe address given below, A COPYRIGHT PROTECTED DOCUMENT © 1302008 'Al rights raserves. Unless ctnerwse specied, no part of this publication may be reproduced or utzd In any form or by any rasan, lector or maghaniel, including photosepyng ahd mioeim, witout permission in uring fem ether ISO at tie adéress below or {80's member body in the covetry ofthe roquoetar. 180 copyignt mice ‘Gese postale 6 « CH-1211 Genove 20 Fen 16422749 0014 Pax = 44 22 749 09 47 E-mail copyight@isa oro Web wwarisa.0rg Published In Switzedand ii (© 180 2000 — alrighterocerved‘Asociatia de Standardizare din Romania, UPRUC CTR, 31/05/2010 Page ‘Marking the original gauge length. Accuracy of testing apparatus 10 Conditions of testing 14 Determination of the upper yield strength. 42 Determination of the lower yield strength .. 43. Determination of proof strength, plastic extension 44 Determination of proof strength, total extension. 45 Method of verification of permanent set strength 46 Determination of the percentage yield point extension 47 Determination of the percentage plastic extension at maximum force. 18 Determination of the percentage total extension at maximum force. 19 Determination of the percentage total extension at fracture 20. _ Determination of percentage elongation after fracture: 24 Determination of percentage reduction of area Annex A (informative) Recommendations concer testing machines ‘Annex B (normative) Types of test between 0.1 mm and 3mm thick . ‘Annex C (normative) Types of test pieces to be used for wire, bars and sactions with @ diameter or thickness of less than 4 mm. 1. ‘Annex D (normativé) "Types of teat pioces to be used for sheets and flats of iicADars equal to or greater than 3 mm, and wire, bars and sections of diameter or thickness equal to or greater than 4mm ‘Annex E (normative) Types of test pieces to be used for tubes, “annex F (informative)’ Estimation of the crosshead separation rate consideration of tthe stiffness (or compliance) of the testing machine (© 180 2000 Allrights reserved il180 6892-1:2009(E) ‘Annex ¢ (informative) Measuring the percentage elongation after fracture if the specified value is leas than 5 % ' 7 Annex H (informative) Measurement af percentage elongation after fracture based on subdivision of the original gauge length ‘Annex | (informative) Determination of the percentage plastic elongation without necking, yr, for long products such as bars, wire and rods. ‘Annex J (informative) Estimation of the uncertainty of measurement, ‘Annex K (informative) Precision of tensile testing — Results from interlaboratory programmes Bibliography. UPRUC CTR, 31/05/2010 ‘Asociatia de Standardizare din Romani w © 180 2000 ~ allrights reservedAsoclatla de Standardizare din Romania, UPRUC CTR, 31/05/2040 1S 6892-1:2009(E) Foreword {SO (the International Organization for Standardization) is a worldwide federation of alone! standards bodies {io0 member boctes). ‘The work of proparing International Standards is normaly carried ‘out through ISO (ee rar apanmitges, Each member body interostod in a subject for which a technical commits Ne been SShblished has the right to be represented on that committee. Intemational organizations, governmental and oe erermental, i Faison win ISO, 2'S0 take part in the work. ISO collaborates, cosely with: the Maertgtional Electrotechnical Commission (IEC) on all matters of electrotachnical standardization, international Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part? ‘The main tack of technical commitiessis to prepare Intemational Standards. Draft Intemational Glandaras seopted by the technical committees are circulated to the member bodies for voting. Pulbleation 2° an Heemnationsl Standard requires approval by at least 75 % of the member bodies casting @ vote. “Attention is drawn to the possbilty that some of the elements ofthis document may be the subject of patent fights. ISO shall not be held responsible for identifying any or all such patent rights. * 180 6892-1 was prepared by Technical Committee ISO/TC 164, Mechanics! testing of metals: ‘Subcommittee SC 1, Uniaxial tasting. “This fist edition of ISO 6892-1 cancels and replaces ISO 6892:1998. 180 6892 consists ofthe folowing parts, under the general tile Metalic matenats — Tensile testing: = Part 1; Method of test dt room temperature “The following parts are under preparation: _= Part 2: Method of test at elevated temperature = Part 3: Mathod of test at low temperature “The following partis planned: = Part 4: Method of test in liquid helium © 150 2009 All rights reserved v‘Asociatla de Standardizare din Romania, UPRUC CTR, 31/05/2010 10 6892-1:2009(E) During discussions conceming the speed of testing in the preparation of ISO 6892:1098, it was decided to recommend the use of strain rate control in future revisions. In this part of ISO 6892, there are two methods of testing speeds available, The first, method A, is based on strain ralas (including crosshead separation rate) and the second, method B, is based on stress rates. Method ‘Ais intended to minimize the variation of the test rates during the moment when strain rate sensitve paramotare are determined and to minimize the measurement uncertainty of the test results. vi (@180 2000 — Al lghts reservedPRUC CTR, 317082010 E é 2 3 : i 3 1S 6892-1:2009(E) INTERNATIONAL STANDARD Metallic materials — Tensile testing — Part 1: Method of test at room temperature 14 Scope “This part of 150 6892 species the method for tonsil testing of metatc materials and defines ne ‘mechenical properties which can be determined at room temperature. NOTE Annex A indicates complementary recommendations for computer controlled testing machines, 2 Normative references ‘The following referenced documents are indispensable for the application of this document. For dated Terances, only the eatin cled apples. For undated roferences, the latest ection of the referenced document {including any amendments) applies. 180 377, Stee! and steot products — Location and preparation of samples and test pisces for mechanical testing 180 2566-1, Stee! — Conversion of elongation values — Part 1: Carbon and fow alley steels 180 2566-2, Stee! — Conversion of elongation values — Part 2: Austenitic steels 180 7500-1, Metalic’ materials — Verification of | static | uniaial | testing _ mantic Part 1: Fension/oompression testing machines — Verieation and calibration ofthe force-measuring system 180 9513, Metallic materials — Calibration of extensameters used in uniaxial testing 3. Terms and definitions For thie purposes of this document, the following terms and definitions apply. 34 gauge length L Tength of the paralol portion of the test piece on which elongation 1s measured at any moment during the test [SO/TR 25679:2005!5] B44 original gauge length i iongth Between gauge length (3.1) marks on the piece measured at room temperature before the test NOTE Adapted from ISO/TR 2567920088 © 180 2000 - All ights reserved 4‘Asoclatia de Standardizare din Romania, UPRUC CTR, 31/05/2040 180 6892-1;2009(E) 342 final gauge length after rupture final gauge length after fracture Ly {éngth between gauge length (3.1) marks on the test piece measured after rupture, at room temperaturo, tho two pieces having been carefully fited back together so that their axes lie in @ straight line NOTE Adapted from ISO/TR 25679:2008!, 32 parallel length Ly length of the parallel reduced section of the test piece TISOFTR 25679:20051) NOTE The concept of parallel length is replaced by the concept of distance between grips for unmachined test pieces. 3.3 elongation increase in the original gauge length (3.1.1) at any moment during the test NOTE Adapted from ISO/TR 25079:2005" a4 percentage elongation ‘elongation expressed as a percentage of the original gauge length, £, (3.1.1) [SO/TR 25679:20051] 344 percentage permanent elongation increase in the original gauge length (3.1.1) of a test piece after removal of a specified stress, expressed as. a percentage of the original gauge lengtn, 25 {MSO/TR 25679:2005), 342 percentage elongation after fracture A permanant elongation of the gauge length after fracture, (Ly ~ Zc). expressed as a percentage of the original gauge length, L, [ISO/TR 25679:200513] NOTE For propotional ttt pisces, ifthe orginal gauge long is not equivalent to 5.655, where 5, is the ‘righa’ crose-secttonal area ofthe parallel length, the symbol 4 should be supplemented by a subscrist indicating the coefficient of proportonaty used, €.9. 4:19 indicates a percentage slongation of the geuge length, Lo of Ange ySo 5 For non-proponional test pieces (see Annex), the symbol 4 should be supplemented by a subscript indicating the original gauge tength used, expressed in milimetiés, ¢.9. 450 mm indicates a percentage elongation of a gauge length, Lo, of 80 mm. 1) 508 )5 55,701. 2 {© 180.2000 —Allighte reservedAsociatia de Standardizare din Romania, UPRUC CTR, 31/05/2010 1SO 6892-1:200%(E) 35 ‘extensometer gauge fength Le ve extensometer gauge length used for measurement of extension by means of an extensometer NOTE 1 Adapted from ISO/TR 25678:2005 NOTE? Formescusinentof ld and prot strength pare, soul span as mash of he partes wag OF a ee ree unaly ava miu, Lg shel be Greater an 0.60 tu ss han epProwinens Ths teat pace ac posse eater dtonts al ing ever at onthe est lee, Further, fr measurement of eeetintore “a eater reaching’ manimur fC Ly shoud be approximately eau 19 Lor 3.6 ‘extension Parase in the extensometer gauge length, L, (3.6), at any moment during the test TISO/TR 25679:2005)] 3.64 percentage extension “strain” extension expressed as 2 percentage of the extensometer gauge lenath, L (3.5) ~ 362 percentage permanent extension peveace in the extensometer gauge length, after removal of a specified stress from the test piece. expressed ‘a6 a percentage of the extensometer gauge length, L. (3.5) nsorTR 25879:20053), 3.6.3 percentage yield point extension Ay As sscontinuous yielding materials, the extension between the start of yiolding and the start of uniform Mlorkhardening, expressed as a percentage of the extensometer gauge length Ze (3:5) NOTE Adapted from (SO/TR 25679:2005"!, ‘See Figure 7. 3.6.4 percentage total extension at maximum force ‘cla! extension (elastic extension plus plastic extension) at maximum force, expressed as a percentage of the ‘extenisometer gauge fength, L, (3.5) ‘See Figure 1. 365 percentage plastic extension at maximum force 4 phasic extension at aiifium foréa, expressed as 2 percentage of the extensometer gauge tenath, 1, (3.5) ‘See Figure 1. (© 180 2000 Allrights reserved 3‘Asociatia de Standardizare din Romania, UPRUG CTR, 31/05/2010 180 6892-1:2009(E) 3.6.6 percentage total extension at fracture A {etal extension (elastic extension plus plastic extension) at the moment of fracture, expressed as a percentage of the extensometer gauge length, Z. (3.5) See Figure 1. 2.7 Testing rate 374 strain rate increase of strain, measured with an extencomoter, in extensometer gauge length, [, (3.5), per time NOTE — See3.0, 372 estimated strain rate over the parallel length 4, value of the increase of strain over the parallel length, £, (3.2), of the test piece per time based on the crosshead separation rate (3.7.3) and the parallel length of the test piece a7 ‘crosshead ceparation rate Ye displacement of the crossheads per time 374 stress rate R increase of stress per time NOTE Sirese rato should only ba used in the elastic part of the test (method 8) 38 percentage reduction of area Zz maximum change in cross-sectional area which has occurred during the test, (S~S,), expressed as a percentage of the original cross-sectional area, 95; z= 522545100 3.9 Maximum force NOTE For materials which display discontinuous yielding, but where no workhardening can be established, Fp is not defines In this part of SO 6882 [see footnote to Figure 8 <}} 391 s maximum force Fon ‘(aterials displaying no discontinuous yielding) highest force that the test piece withstands during the test 4 © 180 2000 — Al sights reeerved7 g z = e § 3 z 5 a : @ 2 i 2 i a 3 1SO 6892-1:2009(E) 39.2 maximum force Fry ‘Faterials displaying discontinsous yielding highest force that tne teat piece withstands during the test after the beginning of workhardening NOTE Soo Figure @ 9) and b) 3.10 stress : Stany moment during the test, force divided by the original cross-sectional area, Se, Of he test piece NOTE 1 Adapted from ISO/TR 25679:2005". NOTE2 — Alreferenoas to stress in this part of ISO 6892 are to engineering stress NOTE In what folows, the dadignatons “roo” and “sress" or “extension, “percentage extonsion” and “tas. OTe sesy."are unod on vanous occasions (2s Fours 2x labels Orin explanations fo the determination diferent pettee) However, for a ganeral description or dafition ata wel-defned pont on 2 curva he designations force’ and crete” or extension’, “percentage extension” and “stain”, respectively, are Interchangeable, 3.104 ‘ tensile strength . Ro tress corresponding to the maximum force, Fr, (3.0) - [ISOITR 25679:2005")] 3.40.2 yiald strength da rena je material oxhbits a yield phenomenon, stress corresponding to the point reached during ihe test al which plastic deformation occurs without any increase in the force, NOTE Adapted trom ISO/TR 25678:2005". 3.40.24 upper yield strength Ron reaximum value of stress (3.10) prior to the first decrease in force NOTE Adaptod from ISO/TR 25679:2008"), ‘See Figure 2. 3.10.22 lower yield strength Ro ‘ahest value of stress (3.10) during plastic yielding, ignoring any inial transient effects [ISO/TR 25679:2008'} See Figure 2. (© 190.2009 — Arights reserved 5Asociatia de Standardizare din Romania, UPRUG CTR, 31/08/2010 ISO 6892-1:2009(E} 3.10.3 4 proof strength, plastic extension R ‘Shess at which the plastic extension is equal 10 a specified percentage of the extensometer gauge fongth 5) NOTE 1 — Adapted from ISO/TR 25679:2005, ‘proof strength, non-proportional. extension”. NOTE 2 — Asuffx is added to the subscript to indicate the prescribed percentage, €9. Ryoa- See Figure 3. 3104 proof strength, total extension 4 eg at which total extension (elastic extension plus plastic extension) is equal to @ speciied percentage of the extansometer gauge length, L, (3.5) NOTE 1 — Adapted from ISO/TR 25679:20050), NOTE? Auf added tothe subse to incon the prescribed percentage, eR: ‘See Figure 4. 310.5 permanent set strength R, siess at which, after removal of force, a specified permanent elongation or extension, expressed respeciively ‘as a percentage of original gauge length, L, (3.1.1), or extensometer gauge length, /. (3.5), Nas not been exceeded TISOMTR 25679:2005% ‘See Figure 5. NOTE _Assuffix is added to the subscript to indicate te specified percentage of the onginal gauge length, Lc, oF of the extensometer gauge length, I, €.9. Roz an ‘racture phenomenon which is deemed to occur when total separation ofthe test piece occurs NOTE Criteria for fracture which may be used for computer controled tests are given in Figure A2. 6 (@180 2000 Allvights reservedAsociatia de Standardizare din Romania, UPRUC CTR, 1/05/2010 1SO 6892-1:2009(E) 4 Terms and symbols “Tho eymbols used in this part of 160 6892 and corresponding designations are given Table 1. ‘Table 1 — Symbols and designations Designation “Teat piace T=] ran [original thiknees of ata test lone or wall ickness of tube gral with ofthe paral length of a Rat teat piece or overage wish ofthe onic! 7 ‘mm | strip taken fom. tube or width of fat re 7 “sm Pesinalcamotr af he paral ong ofa crear test ac, or ameter of ‘ound wire 4| : intemal clameter of tube De Tom [orginal poral dametrof tube | to rom [original gauge length Ze Tm [iva gauge ing or determination of tyn (eae Annex) Te ren __[paralllvength Le mm [extensometer gauge lonath bu torn [total ongth ot west piece te corm [final gouge fongth ater fracture ey mm [inl gauge length aftr fracture for detertination of 4a (see Annex) So Tame original cross-sectional area of the paralioliongth minimum crose-sectional araa after fracture coefficient of proportionality (see 6.1.1) Zz % [percentage reauetion of area Elongation percentage elongation ata fractue (see 3.4.2) percentage plastic erongation without necking (see Annex 1) Extension x [percentage yield point extension percentage plastic extension at maximum force, Fin percentage total extension at maximum force, Fin percentage total extension at fracture extension at maximum forte > aya )elalaye extension at fracture train rate 41, 31 [estimated strain rate over the parallel length zk Pas [ates rate a ‘mm s-*_[erosshead separation rate. (© 150 2009 — Al igh served AIso 6892-1:2009(E) ‘Table 1 — Symbols and designations (continued) ‘Unit Designation Force MPa? [modulus of elasticity 7” MPa _ [slope of the stress-percontaga extension curve ata given moment of the test me ‘MPa [slope ofthe elastic part of the etrose percentage extansion curve Ron MPa __ [upper yield strength c Rox MPa [lower yield strength Rn MPa [renal strength Ry MPa _| proof strenath, plastic extension L ALPE [asoted poranet sat sro % Pa | proof strength, total extension > Symbol usd in stat tube product standards. 2 In the elastic part ofthe stress-percentage extension cure, the value ofthe slope may not necasseriy represent the modus of lasticty, This valve can closely aaree wih the value ofthe modulus of elaseity if optimal conditions (high resolution, double sided, averaging axtansometers, perfect alanment of he test piece, ett) are used. | CALTON — The factor 100 ts necessary If percentage values are used. 5 Principle “The tast involves straining a test piece by tensile force, generally to fracture, for the determination of one or more of ine mechanical properties defined in Clause 3. ‘The test is carried out at room temperature between 10°C and 35°C, unless otherwise specified. Tests carried out under controlled conditions shall be made at a temperature of 23°C £5 °C. Asociatia de Standardizare din Romania, UPRUC CTR, 31/05/2010 6 Test plece 6.1. Shape and dimensions 6.1.4 General ‘The shape and dimensions of the test pleces may be constrained by the shape and dimensions of the metallic product from which the test pieces are taken, ‘The test piece is usually obtained by machining a sample from the product or @ pressed lank or casting. However, products of uniform cross-section (sections, bars, wires, etc.) and also as-cast test pieces (i.e, for cost iron and non-ferrous alloys) may be tasted without being machined. ‘The cross-section of the test pieces may be circular, square, rectangular, annular or, in special cases. some other uniform cross-section. 8 (© 180.2000 —Altights reservedISO 6892-1:2009(E) Preferred test pieces have a direct relationship between the exginal gauge length, La and fhe original cross- sectional area, S,, expressed by the equation L, = KfSq . where kis a coefficient of proportionality, and are called proportional test pieces. The internationally adopted value for kis 5,65. ‘The original gauge length shall be not less than 15 mm. When the cross-sectional area of the test piece is too small for this requirement to be mot with, k= 5.65, a higher value (preferably 11,3) or & non-proportional test piece may be used. NOTE By ueing an orginal gauge longth smalior than 20 mim, the measurement uncertainty ® ineroased For nor-proportione test pioces, the original gauge length, Lis independent of tne onginel crose-soctional fea, Sy “The dimensional tolerances ofthe test pleces shall bein accordance withthe Annexes B10 E (soe 62). Other test piaces such as those specified in relevant product standards er national tendons may be used by fsgreoment with the customer, 0.9. SO 31831) (API SL), ISO 119601 (API SCT), ‘ASTM 23708), ASTM ESN), DIN 50125110), 1acs W2l"3), and Jis 222011"), 6.1.2 Machined test pieces Machined test pieces shall incorporate a transition radius between the eripped onds and the parallel length if aan sSatiorent dimensions, The dimensions of the transition radius are important and i ¢ recommended Hearth So defined in the material specication they are not given in the appropriate annex (See 62). “The gripped ends may be of any shape to sut the arin ofthe testing machine. The axis of the test pioce shall coincide with the axis of application of the force. 3 2 2 5 g 5 ‘The parallel length, Ze or, n the case where the test pisee has no transition radi, the free lenght between the rips, shall always be greater than the original gauge length, 6.1.3 Unmachined test pieces Ifthe test piace consists of an unmachined langth ofthe product or of an unmactinad wst bor te froe length Cahosn ihe gripe shall be sufficient for gauge marks to be at a reasonable distance from the grips (se Annexes 8 10 E). ‘as-cast test pieces shal incorporate a transition radius between the gripped ends and the parallel length. The A ae ee nis tanstion raclus are important and it is recommended that they be defined in We product, Ce sion ot ipped ends may be 0f any shape 10 sult the grips of the testing machine. The parallel length, Ig shell always be greater than the original gauge length, Lo. Asoclatia de Standardizare din Romar 6.2 Types ‘The main typos of test pieces are defined in Annexes B to E according to the shape and type of product, as Thown in Table 2. Other types of test pieces can be specified in product standards. 180 2000 Allights reconved 9Asociatla de Standardizars din Romania, UPRUC CTR, 31/05/2010 (80 6892-1:200%(E) ‘Table 2— Main types of test piece according to product type Dimensions in milimetres Wire — Bars — Sections m@ ON 8S ‘Thickness. Diameter or side ot specified percentage plaste extension R stress Zp. proof strength, plastic extension Figure 3 — Proof strength, plastic extensi Ry (see 13.4) ‘Asociatia de Standardizare din Romania, UPRUG CTR, 31/08/2010 percentage extension percentage total extension stress proof strength, total extension ; Bret g Figure 4— Proof strength, total extension, 2, 2 © 180 2000 = altrights reservedz z 2 2 5 Asociatia de Standardizare din Romvat ISO 6892-1:200%(E) ‘¢_porcentage elongation or percentage extension ‘é_ percentage permanent set extencion or elongation R sess R._ specified permanent set strength Pesos (© 180 2000 All rightsrasecvad Figure 5 — Permanent set strength, &, percentage extension epectid percentage plastic ecension stress proof strength, plastic extension Figure 6 —Proot strength, plastic extension, £, altomative procedure (see 13.1)‘Asociatia de Standardizare din Romania, UPRUC CTR, 3110512010 180 6892-1:2009(E) & « . . 3 | ® - o e 0 e a) Horizontal line method b) Regression method Key tg percentage yield point extension 2 percentage extension R stess uoper veld strength » Horizontal line through the last local minimum point, prior to uniform workhardening. Regression Ino through the range of yielding, prior to uniform workhardening. Line corresponding to the highest slope of the curve occurring atthe start of uniform workhardening. Figure 7 — Different evaluation methods for percentage yield point extension, 4, (© 180 2000 ~ Alright reservedAsociatla de Standardizare din Romania, UPRUG CTR, 347052010 {SO 6892-1:2009(E) g| =) 0 ° 0 ° 9) Res Rn D) Re? Fm 4 e ° ° c) Special case of stress-parcentage extension behaviour ® Koy 2 percentage extension a stress Ran upper yield strength Rr tensile strength For materiale which’ daplay this behaviour, no tensile strength is defined according to this part of ISO 6882. IF necessary, separate agroements can be mada between the partes concerned. Figure 8 — Difforent types of stress-extension curve for determination of tensile strengttt; £m (© 190 2000 — Ad rghts roared 25‘Asociatia de Standardizare din Romania, UPRUC CTR, 3110512040 ISO 6892-1:2009(E) & 4 ‘+ & qo7- : ZA eal pS=r4 i—_ wr ff | ST w I i NW 10+ 1 NS i | \ F AWW I I I 10'r \ LAR LA TET a | 108 feo | be 1 Parton. wt Row Ra Rm t te R, ASA, Raw 4 s R KA is ¥ R 2) Metnod A Key fan rte ‘R stress rate 1 tne progress of ne ent test fe eronshead cont re 1 Scentcmotor ona neo escheat ina 1m Se ange (laste betariou for eteintn ofthe praeters sted (20 Tbl 1 fr doignaton) 1 time range (usually up to frecture) for determination of the parameters ised (see Table 1 for designations) fy time range (plastic behaviour) for determination ofthe parameters listed (see Table 1 for designations) 1 range 1: = 0,000 07 5“, with a relative tolerance of £20 % 2 range: é =0,000 25s"", with a relative tolerance of #20 % 3 range: @ = 0,002 8, with a relative tolerance of £20 % 4 range4; =0,006 7 s"', with a relative tolerance of $20 % (0.4 min, with a relative tolerance of £20 %) + econmonaed. > ‘Expanded range to lower rates, f testing machine is not capable of measuring or coniroling the sain rate (see 10.4.2.5). NOTE Strain rate in the elastic range for method B is calculated from stress rate using a Young moculus of 210 000 MPa (see!) 5 Figure 9 — Illustration of strain rates to be used during the tensile test, Reps Rete Rep Ray Rim» ay Ag As A and Z are determined 26 (© 180 2000 — Alrightsrosonved‘Asoclatia de Standardizare din Romania, UPRUG CTR, 31/05/2010 1S0 6892-1:200%(E) Koy percentage extension R stress | False values, resulting from an abrupt strain rate increase. > Gtresa-atrain behaviour. if strain rate is abruptly increased. NOTE For parameter defirtions. see Table 4 igure 10 — Illustration of an inadmissible discontinuity in the stress-strain curve (© 190 2009 — AN rights reserved a7‘Asoclatia de Standardizare din Romania, UPRUG GTR, 31/05/2010 ISO 6892-1:2009(E) b) After testing Key ‘45, ocginal thickness ofa flat test piece or wll thickness of a tube ‘original width ofthe parallel longth of fat test piece paral iength ‘orignal gauge length ‘otal length of test piece fine! gauge length after race ‘original cross-sectional area ofthe paral! fength ‘ripped ends NOTE The shape ofthe test piece heads is only given as a guide. APEreee Figure 41 — Machined test pleces of rectangular cross-section (see Annexes B and D) (© 180.2000 Allright reserved‘Asociatia de Standardizare din Romania, UPRUC GYR, 34108/2018 ISO 6892-1:2009(E) So, c UL) ral \ GY “| Key Ty eeiginal gauge lenath Sq original eroce-cactional area Figure 12 — Test pleces comprising an unmachined portion of the product (see Annex C) © 180 2008 — All rights reserved 2UPRUC CTR, 31/05/2010 ‘Asociatia de Standardizare din Romani 180 6892-1:2009(E) r Tne Ly b) After testing Key dy. ofkjnalclameter of he paral! length of @ circular test piace L. paraile! length Ly original gauge length Lz. tial length of test piece Ly final gauge length after fracture ‘So ofiginal cross-sectional area of the parallel length 'S,. minimum cross-sectional area after fracture NOTE The shape of the test piece heads is only given as 9 quide. Figure 13 — Machined test pieces of round cross-section (see Annex D) 30 (© 190 2000 — Allighte reserved.Asociatia de Standardizaro din Romanla, WPRUG CTR, 34/05/2010 150 6892-1:2009(E) b) After testing original wall thickness of a tube ‘original extemal dlamoter of a tube criginal gauge fength {otal length of test piece ‘nal gouge length after fracture original eroas-esetlonal area of the parallel length ‘minimum crose-sectional area after fracture gripped ends sepereses Figure 14 — Tost pieces comprising a length of tube (see Annex E) © 160 2000 Allightsresarvad mMUPRUC CTR, 3105/2010 dle Standardizare din Romani 1SQ 6892-1:200%(E) a) Before testing Su NTI. Lai | | WL py b) After teating key 2p ofl wal richness of tube 1, gina! everage wich oo longhadinal stp taken rom a tbe paral ength Za, eriginal gouge length Ly wa feng of test ove 1 inl gauge length afer acure Sq. ofiginal cross-sectional area ofthe parallel length minimum erose-cectionel area after fracture ‘ripped ends NOTE The shape of tne test-piece heads is only given as a guide, Figure 1$— Test plece cut from a tube (see Annex E) 32 © 180 2000 Allrights reserved‘Ascciatia de Standardizare din Romania, UPRUC CTR, 31/05/2010 Annex A (informative) Recommendations concerning the use of computer-controlled tensile testing machines A.1 General ‘This annex contains additional recommendations for the determination of machanical properties DY USO & Toaster controled tensile testing machine, In paricular it provides the recommendations that shoule De taken into account in the software and testing conditions. ‘These recommendations are related to the design, the software of the machine and ts validation, and! to the operating conditions ofthe teneile test. A2 Terms and definitions For the purposes of this annex, the following definition applies. A2A computer-controlled tensile testing machine corthine for which the control and monitoring of the test, the measurements, and the date processing are undertaken by computer A3 Tensile testing machine A341 Design “The machine should be designed in order to provide outputs giving analogue signals untreated by Me a fware: if such outputs are not provided, the machine manufacturar should give raw digital date. win Sratfion on how these rew digitai data have been obtained and treated by the software. They should be therm basic SI unis relating to the foree, tie extension, the crosshead soparation. the time and the test piece dimensions. An example of the format of suitable data files is given in Figure A.1 ‘180 2009 — Alf rights reserved 33‘Asoclatia de Standardizare din Romania, UPRUC CTR, 31/05/2010 om>g 180 6892-1:2009(E) Siaesliat length = 12" ata aoquisiticn xate Sa” Data ev foe scart forge ewhucrion (tysterosis) ~ ke” pata fow for end Coro seauccion (lyetesesis) ~ He "Pike lenge 8 data rows” elle wide M daca cole” YY header test parameters and sample dimensions data Figure A.1 — Example of the format of suitable data files A3.2 Data sampling frequency ‘The frequency banawidth of each of the measurement channels and the date sampling frequency should be sufficiently high to record the material characteristics to be measured. For example tp capture Ray, Equation (A.1) may be used to determine the minimum sampling frequency, fn, in reciprocal Seconds: 6E Fesin = oH 100 At) 34 © 150 2009 Al rights reserved‘Asoctatia de Standardizare din Romania, UPRUC CTR, 31/08/2010 1SO 6892-1:2009(E) where & isthe strain rate, in reciprocal seconds E isthe modulus of elasticity, in megapascal Rey is the upper yiald strength, in megapascals: 4 the relative force measurement accuracy error, expressed as @ percentage, of the testing machine {according to ISO 7500-1). “The choice of fay in Equation (A.1) i duc to tho fac hat it corresponds to @ transient cheractenste during the ree ine anti tected has. yield phenomene, the proof strangth Re Should be used and the required ‘minimum sampling frequency can be halved. i method B (stress rate based) is used, the minimum sampling frequency should be calculated using Equation (A.2): & Rod Soin = 100 (a2) where Bis the stress rate, in megapascats per second. ‘A.4 Determination of the mechanical properties AAA General “The following requirements should be taken into account by the software of the machine. A42 Upper yield strength Rey (3.10.2.1) should be considered as the stress corresponding tothe highest value of the force prior 1 8 Fe oor east 0.8 % of the foree, and followed by a ragion In which the force should nt exceed the previous maximum over a strain range not tess than 0,05 %. A.43 Proof strength at plastic extension and proof strength at total extension 2, (3.10.3) and R, (3.10.4) can be determined by interpolation between agjacent points on the curve. A.4.4 Percentage total extension at maximum force dg (808 3.6.4 and Figure 1) should be considered as the fal extension corresponding to the maximum ofthe ‘sGese-strain curve after yield point phenomena. For some materials it is necessary to smooth ihe stress-strain curve in which case 2 polynomial regression is. tor aomendes, The smoothing range may have an influence on the result. The smoothed curve should be 4 reasonable representation of the relevant part of the original stress-strain curve. AA5 Percentage plastic extension at maximum force ‘Ay (988 3.6.5 and Figure 1) should be considered as the plastic extension corresponding to the maximum of the stress-strain curve after yield point phenomena. For come metorials it is necessary to smooth the stress-strain curve In which case a polynomial regression ie coe eorrended. The smoothing range may have an influence on the result. The smoothed curve should be 2 feasonable representation of the rolevant part of the original stress-strain curve. (2180-2000 Al rights reserved 35‘Ascciatia de Standardizare din Romania, UPRUC CTR, 1105/2010 ISO 6892-1:2009(E) AA.6 Percentage elongation at fracture A481 Determine 4, with reference to the definition of fracture in Figure A.2. ‘The fracture is considered to be effective when the force between two consecutive points decreases: a) by more than five times the difference between the value of the previous two points, followed by decrease to lower than 2 % of the maximum tensile force; b) lower than 2 % of the maximum tensile force (soft materials). ‘Another useful method for detecting the fracture of the test piece is to monitor the voitage or electric current {through the test piece, when the values measured just before the current is interrupted are taken as those at fracture. key F force Fn maximum force Fyet_foroe at measuring point +4 AF ject force differance between measuring point and n—1 ‘Farin force diference between measuring point n +1 and n + time 1 fracture fo} data point Criteria for fracture [aFprtal > 514F pl 4 analor Fyet £0.02Fin Figure A2— Schematic representation for definition of fracture of the teat piece 36 © 150 2000 ~ Al rights reservedPRUE CTR, 31/952010 ‘Asoclatia de Standardlzare din Romani ISO 6892-1:2009(E) (A462 ttthe extensometer is Kept on and the extonsion is measured untl the fracture, evaluate he vale ‘at point 4 in Figure A2. Ad6.3_ \fthe extensometer is removed ori the extension measurement is interrupted before fracture Het ee 8 aximum foros, Fee then itis permitted 10 use crosshead displacement to determine We ‘additional Slongation between removal ofthe extensometer and fracture. The method used should be verifiable. A.A.7 Measurement of the slope of the curve in the elastic range In order to be valid for test pieces of unknown characteristics, the method used should not rely upon shy predefined stress limit, unless this is defined in the product standerd or by agreement between parties to the test. “The most convenient methods baséd on the calculation of the characteristics of a sliding segment are the most convenient. The parameters are: ‘a)_ the length of the sliding segment (number of points used): 'b) the equation chosen as reference to define the slope of the curve. NOTE Ifthe straight portion of the force extension curve is not clearly defined, efer to 12.3. “The slope of the curve in the elastic range corresponds to the meen slope in a range whore the folowing conditions are fufited: )_ the slope of the sliding eegment is constant; ) the selected range is representative. In any case, it should be recommended that pertinent limits for the range can be selected by the user In order to eliminate unrepresentative values of the slope of the curve in the elastic range. References to these and other acceptable methods are given in References [5] (171 [18], {18} ‘A recommended method to determine the slope of the elastic ine for evaluation of Ryo 2 (Reference [20]: — linear regression ofthe linear range: — lower limit: 10 % of poi — upper limit: ~50 % of Rgo.25 — to.getmore exact dota for Ryo.» the elastic ine must be checked and if necessary recalculated with other A5 Validation of the software for determination of the tensile properties ‘The efficiency of the methods used by the testing sysiem io determine tho various material charactaistes Te enecked by comparison with resuils determined in the tadional manner by examinaton/caleslafon from plots of analogue or digital data. Data which are derived directly from the fhachino transducers of Feipifors should be collactes and processed using equipment with requency bandwidth, sampling frequency and uncertainty, of at feast equal to those used 10 provide the machine computer-calculated results. Confidence may ts’ placaid in the accuracy of the machine computer processing if fleencas in arinmetic Coane between computer-determined values and those determined manually on the same test plese re sel ror ine purposes of assessing the accoptabilty of such diferences. fe similar test pieces shouts Be Sra fie the average alfference for each relevant property should fie wthin the limits shown in Table A. {8180 2009 All ights exerved 7ISO 6892-1:2009(E) NOTE 1 This procedure confirms only that the machine finds the material characteristics for the particular test piece shape, material tested and conditions used, fives no confidence that the properties of the material tested are either corrector fit for purpose, If other methods are used, @.g. injection of a pre-determined set of data from a known material with @ recognized level of quality assurance, these should meet the requirements mentioned above and those in Table At. NOTE 2 AS part of the EUsunded TENSTAND project (GBRD-CT-2000-00412), ASCII data files were produced with Torsed valuet’ of tensilo properties thet may ‘be used for validation of software, [Avalable (2000-07-22) at iupilwww nplco ubtenstand) Further details are given in References [21] and (22) ‘Table A — Maximum permitted differences between computer-derived and manually derived results [ream 7 Fj Relative ® Absolute® Reiative® yor ose | 2éPa 0.35 % Rot £05% 2uea | <035% Fa <1% 4MPa 0,06 % Fa. 505% 2a 50.38 % Pn £05 % 2MPe £0.85 % 4 = =2% = D's the diference betwen the result of manual evaluation, and the resut of computer evaluation, R, fore test pioce| == 4% ‘2 isthe numberof identical est places fom one sample (> 3). © The higheet ofthe relative and absolute valuas shouldbe taken into account ‘Asociatia de Standardizare din Romania, UPRUC CTR, 31/05/2010 38 (© 150 2000 Al rights reservedAsociatia de Standardizare din Romania, UPRUC CTR, 31/05/2010 180 6802-1:2009(E) Annex B (normative) Types of test pieces to ‘be used for thin products: sheets, strips and flats between 0,1 mm and 3 mm thick NOTE For products of les than 0,6 mm thickness, special precautions may be necessary B.1 Shape of the test piece Gonorally, the test piace has gripped ends which are wider than the parallel length. The parallel length, fos Sha bo Zonnocted to the ands by means of transition curves with a radius of at least 20 mm. The width of these ends should be > 1,28, where 6, is the original width. By agreement, the test piece may slso consit of stip with parallel sides (parallel sided test piece), For Products of width equal {0 oF fess than 20 mm, the width ofthe test piece may be the same as that of he product. B.2 Dimensions of the test piece “Three diferent non-proportional test piece geometries aro widely used (see Table B.1). ‘The parallel length shal not be tess than Ly + be/2. in case of dispute, the length L, + 2b, should be used, uniess there is insufficient material For parallel side test piaces less than 20 mm wide, and unless otherwise specified in the product standard, the Griginal gauge length, Z., shall be equal to 50 mm. For this type of test piece, the free length between the grips shall be equal to Ly + 3b. When measuring the dimensions of each test piece, the tolerances on shape given in Table B.2 shall apply. For test pieces where the width is the same as that of the product, the original cross-sectional area, S., shall be calculated on the basis of ihe measured dimensions of the test piece. “The nominal width of the test piece may be used, provided that the machining tolerances and tolerances oF eree ‘given in Table B.2 have been complied with, to ‘avoid measuring the width of the test piece at the time e test © 190 2008 ~ Ali rights recorvod : 39180 6892-1:200%(E) ‘Table B.1 — Dimensions of test pieces Dimensions in millimetres Test piece | Width | Original gauge Parallel length Free length between the grips type i length a for parallel sided test piece Recommended 12521 2081 3 2541 508 60 2 The rao Lh and Lz, of type 3 fet plece i comparison tone of pes 1 and 2 is very low. As a rasut the properties especially the elongation ator race (absolute value and scaller Tenge), measured wih ths test plece wil be efferent from tho other test piece types. ‘Table B.2 — Tolerances on the width of the test plece Dimensions and tolerances in milimetres ‘Nominal width of the test piece ‘Machining tolerance * Tolerance on shape 12.5 £0005 0.98 20 £0.10 0.12 2 0,10 0.12 Treas tolerances are eppicabie F the nominal valve ofthe orginal cose-eactonal area, S,, is to be included inthe ealeuiaton| without Roving to measure > sfaximum deviation between the messurements ofthe width along the entra pare iength, Le, ofthe test place, B.3 Preparation of test pieces ‘The test pieces shall be prepared so as not to affect the properties of the sample. Any areas which have been hardened by shearing or pressing shall be removed by machining. These test pieces are predominantly prepared from sheet or strip. If possible, the as-rolled surfaces should not be removed. ia de Standardizare din Romania, UPRUC CTR, 31/05/2010. NOTE __ The praparation of these test pisces by punching can resuit in significant changes to the material properties, epecially the yield/proof strength (due to warkhardening). Materials which exhibit high workhardening should, general bbe prepared by miling, grinding etc. materials, it is recommended that strips of identical widths should be cut and assembled into a bundle with intermediate layers of @ paper which is resistant to the cutting oil. Each small bundle of strips ‘should then be assembled with a thicker strip on each side, before machining to the final dimensions of the test piece. The tolerance given in Table B.2, @.g. 40,05 mm for a nominal width of 12,5 mm, means that no test piece shall have a width outside the two values given below, if the nominal value of the onginal cross-sectional area, Sp. is to be included in the calculation without having to measure it: 42,5 mm +0,05 mm = 12.55 mm 7 12,8 mm — 0,05 mm = 12,45 mm 40 © 180 2000 — Alrighta rozorvedAsoclatia de Standardizare din Romania, UPRUC CTR, 31/05/2010 1g0 6892-1:2009(E) B.4 Determination of the original cross-sectional area ‘Sq shall be calculated from measurements of the dimensions ofthe test piece. “The error in determining tha original cross-sectional area shall not exceed + 2%. AS the greatest pert of tie sre Mormaly recut from the measurement ofthe thickness of the test piece, the errar In measurement of the width shall not exooed ¢ 0,2 %, In order 10 achieve test resulls with a reduced measurement uncertainty itis recommended that the onginal caoes sectional area be datermined with an accuracy of 1 % or botor. For thin materials special measurement techniques may be required. © 190 2009 All sights reserved1S0 6892-1:2009(E) Annex C (normative) Types of test pieces to be used for wire, bars and sections with a diameter or thickness of less than 4 mm C1 Shape of the test piece “The tast piece generally consists of an unmachined portion of the product (see Figure 12). €.2 Dimensions of the test plece ‘The original gauge length, Zo, shall be taken ae 200 mm:+2.mm, or 100 mm +1 mm. The distance between the grips of the machine shall be equal to at least Z, + 32, but a minimum of L +20 mm. If the percentage elongation after fracture is not to be determined, a distance between ‘the grips of at least ‘50 mm may be used. €.3 Preparation of test pleces It me product is delivered coiled, care shall be taken in straightening it, CA Determination of the original cross-sectional area Determine 5, to an accuracy of & 1 % or batter. For products of circular cross-section, the original cross-sectional ares may be calculated from the arithmetic mean of two measurements carried out in two perpendicular directions. ‘The original cross-sectional area, Sq, in square milimetres, may be determined from the mass of a known length and its density using Equation (C.1): ‘Asociatia de Standardizare din Romania, UPRUC CTR, 31/05/2010 1000 m Pla (ey mis the mass, in grams, of the test piece; 14 is the total length. in milimetres, of the test piece; pis the density, in grams per cubic centimetre, ofthe test piace material, 4 42 (© 180 2000 — Al ight reosrvedUPRUC CTR, 31/05/2010 Asociatia de Standardizare din Romania, Annex D (normative) Types of test pieces to be used for sheets and flats of thickness equal to or greater than 3mm, and wire, bars and sections of diameter or thickness equal to or greater than 4mm D.1 Shape of the test piece Usually, the test piace is machined and the parallol length shall ba connected by means of transition rad 10 the grtbed ends which may be of any suitable shape for the gripe of the testing machine (see Figure 19). The minimum transition radius between the gripped ends and the parallel longth shall be: a) 0,75dq, where da is the diameter of the parallel length, for the cyincticel test plecest b) 12mm for other test pieces. Sections, bare, oto., may be tested unmachined, if required. “The cross-section ofthe test piece may be circutar, square, rectangular or, in special cases, of another shape. For test pieces with a rectangular cross-section, its recommended that the width to thickness ratio should not ‘exceed 8:1. In general. the aiameter of the parallel length of machined cylindcal test pieces shell be not lees than 3 mm D.2 Dimensions of the test piece D.2.1 Parallel length of machined test piece “The parallel length, Z,, shall bo at least equal to: a) Ly + (de/2) for cylindrical test pieces; b) 1+ 1,5Y5, for other test pieces. In cases of dispute, the length L, + 2d. or Lo + 248, shall be used depending on the type of test pleco, untess there is insufficient material. D.2.2 Length of unmachined test piece “The free longth between the grips of the machine shall be adequate for the gauge marks to be at least 2 distance of ./S, from the grips. 1 (© 190 2009.- AN ights reserved : 43