1、BRITISH STANDARDBS EN 10325:2006Steel Determination of yield strength increase by the effect of heat treatment Bake-Hardening-IndexThe European Standard EN 10325:2006 has the status of a British StandardICS 77.040.10; 71.080.20g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g5
2、3g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 10325:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 September 2006 BSI 2006ISBN 0 580 48971 XNationa
3、l forewordThis British Standard was published by BSI. It is the UK implementation of EN 10325:2006. The UK participation in its preparation was entrusted by Technical Committee ISE/NFE/4, Mechanical testing of metals, to Subcommittee ISE/NFE/4/1, Uniaxial testing of metals.A list of organizations re
4、presented 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 contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.Amendments
5、issued since publicationAmd. No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 10325August 2006ICS 77.040.10; 71.080.20English VersionSteel - Determination of yield strength increase by the effect ofheat treatment Bake-Hardening-IndexAciers - Dtermination de laugmentation de la limi
6、teapparente dlasticit due un traitement thermique (indexde durcissement la cuisson Bake-hardening)Stahl - Bestimmung der Streckgrenzenerhhung durchWrmebehandlung (Bake-Hardening-Index)This European Standard was approved by CEN on 7 July 2006.CEN members are bound to comply with the CEN/CENELEC Inter
7、nal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.T
8、his European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the
9、 national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United
10、Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 10325:2006: EEN 103
11、25:2006 (E) 2 Contents Foreword3 1 Scope 4 2 Normative references 4 3 Terms and definitions .4 4 Symbols and designations .6 5 Principle6 6 Test equipment 6 7 Test pieces .6 8 Testing procedure6 8.1 Testing conditions.6 8.2 Heat treatment conditions 6 8.3 Determination of Bake-Hardening-Index (BH2)
12、.7 9 Test report 7 EN 10325:2006 (E) 3 Foreword This document (EN 10325:2006) has been prepared by Technical Committee ECISS/TC 1 “Steel - Mechanical testing”, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of
13、 an identical text or by endorsement, at the latest by February 2007, and conflicting national standards shall be withdrawn at the latest by February 2007. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this E
14、uropean Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. E
15、N 10325:2006 (E) 4 1 Scope This document specifies the method for the determination of yield strength increase by the effect of heat treatment (Bake-Hardening-Index) for steel. NOTE This test is applied in particular, to steels showing a mechanism of bake hardening, which are specially intended for
16、automotive industry. 2 Normative 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. EN 10
17、002-1:2001, Metallic materials Tensile testing Part 1: Method of test at ambient temperature 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 10002-1:2001 and the following apply. NOTE However it should be noted that in the context of this document, th
18、e term “yield strength“ also covers 0,2 % proof strength in addition to its definition in EN 10002-1. 3.1 Bake-Hardening-Index (BH2) increase of yield strength between a reference condition after a 2 % plastic pre-strain and the condition obtained after a heat treatment simulating the usual industri
19、al paint processes (see Figure 1) NOTE The heat treatment of simulation is specified in 8.2. EN 10325:2006 (E) 5 Key 1 Stress 2 Strain 3 Application of a 2 % plastic pre-strain 4 Tensile test after heat treatment on the same test piece Figure 1 Illustration of the determination of BH2EN 10325:2006 (
20、E) 6 4 Symbols and designations The symbols used in this document and the corresponding designations are given in Table 1. Table 1 Symbols and designations Symbol Unit Designation Rp2,rMPaaStress corresponding to a 2 % plastic prestrain measured on the test piece ReL,tMPa Lower yield strength measur
21、ed on the test piece initially prestrained at 2 % and then heat treated Rp0,2,tMPa 0,2 % proof strength measured on the test piece initially prestrained at 2 % and then heat treated BH2MPa Bake-Hardening-Index a1 MPa = 1 N/mm. 5 Principle The test determines an index giving the increase of yield str
22、ength of a test piece submitted to a 2 % plastic pre-strain, then to a specified heat treatment. 6 Test equipment The test equipment shall be in accordance with EN 10002-1. 7 Test pieces The test pieces shall be according to EN 10002-1. 8 Testing procedure 8.1 Testing conditions The tensile test sha
23、ll be performed according to Annex A of EN 10002-1:2001. The testing rate given in EN 10002-1 for the beginning of the tensile test, shall only be increased after the determination of ReLor Rp0,2. During the pre-straining of the test pieces, the testing rate shall be kept constant up to a plastic pr
24、e-strain of (2 0,05) %. All tensile tests used to characterize a steel shall be performed with the same actual testing rate. 8.2 Heat treatment conditions A test piece temperature of 170 C shall be achieved within 7 min. The heat treatment time of (20 0,5) min commences when a test piece temperature
25、 of 168 C is achieved. The heat treatment equipment used shall be capable of keeping the prescribed test piece temperature (i.e. 170 C) at 2 C. The temperature measuring device shall have a resolution of no more than 1 C with a maximum measuring uncertainty of 2 C. After the holding time, the test p
26、iece shall be air cooled to room temperature, i.e. (23 5) C. EN 10325:2006 (E) 7 8.3 Determination of Bake-Hardening-Index (BH2) The BH2-Index is the difference between the proof strength, Rp2,r, of the 2 % plastically strained test piece (modulus of elasticity of steel considered to be 200 000 MPa)
27、 and the lower yield strength, ReL,t, or the proof strength, Rp0,2,t, of the same test piece after an additional heat treatment at 170 C with a holding time of 20 minutes. Determining ReL,tor Rp0,2,tafter heat treatment, the cross-sectional area of the test piece after a plastic pre-strain shall be
28、used. rp2,p0,2tteL,2or RRRBH = )( (1) 9 Test report 9.1 If testing of BH2is carried out in combination with the conventional test according to EN 10002-1, the Bake-Hardening-Index shall be added to the test report. 9.2 If testing of BH2 is carried out separately, the test report shall contain at lea
29、st the following information: a) reference to this European Standard; b) identification of the test piece; c) location and direction of sampling; d) test result. BS EN 10325:2006BSI389 Chiswick High RoadLondonW4 4ALBSI British Standards InstitutionBSI is the independent national body responsible for
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