1、CEN PREN*E83L EDITION*L 90 W 3404589 0036276 4 W A. E. C. M .A. STAN DAR D NORME A.E.C.M.A. . A.E.C.M.A. NORM prEN 2831 Edition 1 Decembor ISSO EDITE PAR LASSOCIATION EUROPEENNE DES CONSTRUCTEURS DE MATERIEL AEROSPATIAL 88. boulevard Malesherbes, 70008 PARIS -TEL. 45-63-82-85 UDC : Key words : ENGLI
2、SH VERSION Aerospace series Hydrogen embrittlement of steels Test by slow hending Srie arospatiale Luft- und Raumfahrt Fragilisation des aciers par lhydrogne Essai par flexion lente Wasserstoffversprdung von Stahlen Langsamer Biegeversuch This Aerospace saries standardhas been drawn up under the res
3、ponsibility ofAECMA (Association Europenne des Constructeurs de Matriel Arospatial). It is published on yellow paper in three equivalent versions (English, French, German). It will be submitted as a draft European Standard to CEN (European Committee for Standardization) for final vote. r versions in
4、 French and icriiian languages can be supplied Technopolis 64 199, riie Jean-Jacquus Rousseau .-m-ahq. 1990-1 2-28 92138 ISSY LES MOULIMEAUX CEOEX - TRANCE - CEN PREN82831 EDITION*L 90 3404589 00Lb277 b prEN 2831 Page 3 -_- 1 This standard specifies a test method by slow bending, which is used to as
5、sess the hydrogen embrittlement of steels during chemical or electrolytic surface treatments. Scope and field of application This test is also used to verify the recovery of the initial ductility during de-embrittlement treatments. It shall be applicable whenever referenced. 2 Apparatus Bending test
6、 machine with the following characteristics : - the chucks shall avoid any effects due to clamping in the region of cracking, - one of the chucks shall be fixed and the other movable; the fixed chuck shall be fitted with an interchangeable bending block the diameter of which may be between 2 mm and
7、6 mm; the movable chuck shall have a deflection rate which can be adjusted between 4 “/min and 18 “/min, - figures 2 to 4) with a precision of - + 0,s O, 0 be fitted with a device allowing to measure the angles ci mf1 and wf2 (see O - be fitted with a magnifier of 10 X in order to reveal the first c
8、rack occurring. 3 Test specimens They shall : - be cut from a bar or sheet along the grain direction, - have the following dimensions. : . length : 180 mm to 200 mm, . width : 15 mm to 20 mm, thickness : 1,8 mm to 4 mm, O straightness deflection over the length less than 0,25 mm, - submitted to a st
9、ress relief of at least 2 h at 150 OC without decarbrization, be machined along the grain direction to a surfac.e roughness Ra 1,6, then 4 Procedure if specified, and a( ) is determined on the same f2 Each bending angle (a test specimen, At leas? 3 specimens shall be used. The test specimens shall b
10、e in the same condition as the parts they represent. 0 Previous page is blank CEN PREN*283L EDITION81 40 m 3404589 00Lb278 8 m prEN 2831 Page 4 Note 1 : Test specimens possibly of a different steel grade with a higher strength than the pieces may be used, Note 2 : The fracture angle of the test spec
11、imens per bending shall not exceed the deflection angle of the movable chuck. The diameter of the bending block and the deflection rate of the movable chuck shall be functions of material and thickness of the test specimen. Place the specimen in the test machine (see figure i). Bend the test specime
12、n under the specified deflection rate of the movable chuck until the first crack occurs in the centre part of the test specimen and measure thebending angles cio, df 1, if specified, and %2. Angle o( shall be measured with in max. 1 h after the surface treatment. fl 5 Expression of results - Ductili
13、ty after surface treatment : dfl / qo x 100, in %, - Final ductility : rxf2 / do x 100, in 2. 6 Fault sanction The value of final ductility shall be specified in the process standard. ,7 Test report It shall include the following : reference to this standard, numbers of the test pieces, nature of th
14、e coating, thickness of the coating, diameter of the bending block and deflection rate of the movable chuck, values of bending angles measured, test result. .- I -. CEN PREN*2833 EDITION*3 90 3404589 0036279 T prEN 2831 Paw 5 -= Test specimen Block Block O I L R of the bending block Figure I - Placing of the test specimen before testing r Detail W .- y J Figure 2 - Bending angle prior to chimical or electrolytic treatment Detail W - Mirror-view I
