【正文】 ? edges of the testpiece may be machined when practical. They may be rounded to a radius of approximately 2 mm. 5 Hardness test Hardness test can be a convenient means for checking the homogeneity of a lot 。 I S C H ES KOM I TEE F 220。Licensed Copy: Institute Of Technology Tallaght, Institute of Technology, Tue Nov 14 09:45:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 國內(nèi)外標(biāo)準(zhǔn) 大全 網(wǎng) 國內(nèi)外標(biāo)準(zhǔn) 下載地址 BRITISH STANDARD BS EN 4852:2020 Aluminium and aluminium alloys — Sheet, strip and plate — Part 2: Mechanical properties The European Standard EN 4852:2020 has the status of a British Standard ICS BS EN 4852:2020 Amd. No. Date Comments Licensed Copy: Institute Of Technology Tallaght, Institute of Technology, Tue Nov 14 09:45:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI National foreword This British Standard is the official English language version of EN 4852:2020. It supersedes BS EN 4852:1995 which is withdrawn. The UK participation in its preparation was entrusted by Technical Committee NFE/35, Light metals and their alloys, to Submittee NFE/35/5, Wrought aluminium and aluminium alloys, which has the responsibility to: — aid enquirers to understand the text。 R NOR M UNG Management Centre: rue de Stassart, 36 B1050 Brussels 169。 it can also be used for a quick semiquantitative check of the thermal treatment to which the material has been submitted or, as a first approach, for material identification purpose. However its accuracy is generally less than can be expected from a tensile test which it cannot replace. EN 4852:2020 (E) 8 Licensed Copy: Institute Of Technology Tallaght, Institute of Technology, Tue Nov 14 09:45:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI NOTE Hardness can be measured at different locations, . on the surface of the product or on the tensile specimen. For some materials, results can be different. The values in Tables 2 to 39 are typical Brinell hardness (HBW) values for a test carried out according to EN ISO 65061 with a 2,5 mm diameter steel ball. They are given for information only. If the Brinell hardness test is not possible (because of thin gauge or soft temper) then Vickers hardness test, according to EN ISO 65071, can be used. In that case the values wi ll be approximately 10 % above the stated Brinell values. Table 1, given for convenience, shows for several HBW values the minimum gauge down to which the hardness measurement remains valid, according to the rules stated in EN ISO 65061, using a 2,5 mm diameter steel ball and a load of 612,9 N. Table 1 — Minimum material gauge and Brinell hardness values Brinell hardness (HBW) 30 40 50 60 70 80 90 100 minimum gauge (mm) 2,1 1,6 1,3 1,1 0,91 0,80 0,71 0,64 Brinell hardness (HBW) 110 120 130 140 150 160 170 180 minimum gauge (mm) 0,58 0,53 0,49 0,45 0,42 0,40 0,37 0,35 6 Electrical conductivity Electrical conductivity measurements are required for lot acceptancepurposes, in the case of alloy EN AW7075 in the tempers T73, T7351, T76 and T7651, in order to assess the resistance to stresscorrosion cracking or the exfoliationcorrosion resistance of the material as applicable. The specimen for electrical conductivity testing shall be taken adjacent to the tensile test specimen. The measurement shall be carried out by the eddycurrent method as specified in EN 20201. The reference blocks to be used shall be agreed between producer and purchaser. The results shall be rounded to the nearest 0,1 MS/m, using the rounding rules set out in annex A. The acceptance criteria are specified in Table 38. 7 Stresscorrosion resistance Plate made of alloy EN AW7075 in the T73 and T7351 tempers and over 25 mm in thickness, shall be capable of exhibiting no evidence of stresscorrosion cracking when subjected to ISO 9591 accelerated stresscorrosion cracking test. For the purpose of this standard the following provisions shall apply: ? a minimum of three adjacent replicate test pieces shall be taken from each specimen and submitted to the test。 ? width of the test piece shall be at least 20 mm and preferably 40 mm to 50 mm. For material less than 20 mm wide, the width of the testpiece shall be the full width of the material。E N DE NOR M A L I S A T I O N EUR O P 196。 — present to the responsible international/European mittee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed。 2020 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 4852:2020: E EN 4852:2020 (E) 2 Licensed Copy: Institute Of Technology Tallaght, Institute of Technology, Tue Nov 14 09:45:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Contents Foreword...................................................................................................................................................................... 4 1 Scope ...............................................................................................................