1、BRITISH STANDARD AEROSPACE SERIES CONFIRMED JUNE 1999 BS2T68:1980 (Superseding BST68) Specification for Cold drawn18/10 chromium-nickel corrosion-resisting steel tube (Niobium stabilized:800MPa) (Weldable) UDC629.7:669.152624-194-124.2-462:669.14.018.8:621.791.011BS2T68:1980 This BritishStandard, ha
2、ving been prepared under the directionof the Aerospace Standards Committee, was published under the authority ofthe Executive Board on 29February1980. Itcomesintoeffect (see note1) on 30May1980 BSI02-2000 The following BSI references relate to the work on this standard: Committee reference ACE/15 Dr
3、aft for comment78/77607 DC ISBN 0 580 11168 7 A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligati
4、ons. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, page1 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments
5、issued since publication Amd. No. Date of issue CommentsBS2T68:1980 BSI 02-2000 i Contents Page 1 Inspection and testing procedure 1 2 Process of manufacture 1 3 Chemical composition 1 4 Surface dressing 1 5 Condition 1 6 Heat treatment 1 7 Mechanical properties 1 8 Susceptibility to intercrystallin
6、e corrosion 1ii blankBS2T68:1980 BSI 02-2000 1 NOTE 1Attention is drawn to the fact that this BritishStandard does not come into effect until3months after the date of publication. This is to enable users of the standard to obtain copies and make the necessary amendments to their documentation before
7、 the effective date. NOTE 2Tube of the same composition for use in the softened condition is covered by BST66. 1 Inspection and testing procedure 1.1 General. This BritishStandard shall be used in conjunction with sections1 and3 of the latest issue of BST100. 1.2 Sulphur printing or deep etching tes
8、ts. One sample shall be taken from each ingot for deep etching tests. 2 Process of manufacture The steel shall be manufactured by an electric process. 3 Chemical composition The steel shall contain: 4 Surface dressing The steel shall be overall dressed. 5 Condition The tube shall be supplied in eith
9、er of the following conditions, at the option of the manufacturer, unless a specific condition is stated on the order: a) cold drawn, or b) cold drawn and tempered. 6 Heat treatment The tempering treatment shall consist of heating uniformly at a temperature of not more than550 C, followed by cooling
10、 in a suitable manner. 7 Mechanical properties 7.1 Tensile test. The mechanical properties obtained from test pieces, selected, prepared and tested in accordance with the relevant requirements ofBS T100, shall be as follows. 7.2 Flattening test. The distance between the inner surfaces of the test pi
11、ece in the direction of flattening shall be8T or0.75internal diameter, whichever is the smaller. 7.3 Hardness test. The hardness of the tube shallbe: 229min./375max.HB or 235min./400max.HV 8 Susceptibility to intercrystalline corrosion 8.1 The tube shall be subjected to the intercrystalline corrosio
12、n test in accordance with the relevant requirements of BS T100. 8.2 The distance between the inner surfaces of that part of the test sample that is flattened shall be as specified in7.2. 8.3 There shall be no evidence of fissuring or crazing of either of the surfaces of the test sample. Element % mi
13、n. max. Carbon Silicon Manganese Phosphorus Sulphur Chromium Nickel Niobium 0.2 0.5 17.0 9.0 10 carbon content 0.08 1.0 2.0 0.035 0.025 19.0 12.0 1.0 0.2%proof stress Tensile strength min. min. max. MPa (=N/mm 2 ) MPa (=N/mm 2 ) MPa (=N/mm 2 ) 700 800 1100 NOTEInformation on SI units is given in BS3
14、763 “The International System of units (SI)” and BS350 “Conversion factors and tables”.BS2T68:1980 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe a
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