1、BRITISH STANDARD AEROSPACE SERIES CONFIRMED MARCH 1991 BS T76:1978 Incorporating Amendment No.1 Specification for Chromium- molybdenum steel tube(770MPa) (Weldable) UDC 629.7:669.152628 144 462:621.791.011BST76:1978 This BritishStandard, having been prepared under the directionof the Aerospace Stand
2、ards Committee, was published under the authority ofthe Executive Board on 30November 1978 BSI 02-2000 The following BSI references relate to the work on this standard: Committee reference ACE/15 Draft for comment77/78627DC ISBN 0 580 10356 0 A British Standard does not purport to include all the ne
3、cessary 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 obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, page1
4、 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 issued since publication Amd. No. Date of issue Comments 5184 September 1986 Indicated by a sideline in
5、 the marginBST76:1978 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 Decarburization 1 8 Mechanical properties 1ii blankBST76:1978 BSI 02-2000 1 1 Inspection and testing proc
6、edure 1.1 General. This BritishStandard shall be used in conjunction with sections one and two of the latest issue of BS T100. 1.2 Sulphur printing or deep etching tests. One sample shall be taken from each ingot for sulphur printing or deep etching tests. 2 Process of manufacture The steel shall be
7、 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 any of the following conditions, at the option of the manufacturer, unless a specific condition is stated on the orde
8、r: a) cold drawn and tempered; b) hardened and tempered; c) normalized and tempered. 6 Heat treatment 6.1 Hardening. The hardening treatment shall consist of heating uniformly at a temperature between870 C and910 C, followed by quenching in oil or water. 6.2 Normalizing. The normalizing treatment sh
9、all consist of heating uniformly at a temperature between870 C and910 C, followed by cooling inair. 6.3 Tempering. The tempering treatment shall consist of heating uniformly at a temperature of not more than675 C, followed by cooling in a suitable manner. 7 Decarburization The depth of decarburizati
10、on, at either of the surfaces, shall be not greater than0.1mm or2% ofthe nominal thickness, whichever is the lesser. 8 Mechanical properties 8.1 Tensile test. The mechanical properties obtained from test pieces, selected, prepared and tested in accordance with the relevant requirements of BST100, sh
11、all be as follows. NOTEInformation on SI units is given in BS3763 “The International System of units (SI)” and BS350 “Conversion factors and tables”. 8.2 Flattening test. The distance between the inner surfaces of the test piece in the direction of flattening shall be8T or0.88bore diameter, whicheve
12、r is the smaller. 8.3 Hardness test. The hardness of the tube shallbe: 229min./285max. HB or 240min./300max. HV Element % min. max. Carbon Silicon Manganese Phosphorus Sulphur Chromium Molybdenum Nickel 0.22 0.15 0.5 0.9 0.15 0.29 0.35 0.8 0.020 0.015 1.2 0.25 0.30 0.2 % proofstress Tensile strength
13、 min. min. max. MPa (=N/mm 2 ) MPa (=N/mm 2 ) MPa (=N/mm 2 ) 700 770 970BS T76:1978 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 and at the inter
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