1、BRITISH STANDARD AEROSPACE SERIES CONFIRMED JUNE 1999 BS T 77:1980 (Superseding BST56) Specification for Chromium- molybdenum steel tube(900MPa) (Weldable) UDC 629.7:669.152628-194-462:621.791.011BST77:1980 This BritishStandard, having been prepared under the directionof the Aerospace Standards Comm
2、ittee, was published under the authority oftheExecutive Board on 29February 1980. Itcomesintoeffect (seenote1)on 30May1980 BSI 02-2000 The following BSI references relate to the work on this standard: Committee reference ACE/15 Draft for comment78/77607DC ISBN 0 580 11166 0 A British Standard does n
3、ot 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 obligations. Summary of pages This document comprises a front cover, an inside
4、front cover, pages iandii, 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 issued since publication Amd. No. Date of issue CommentsBST77:1980 BSI
5、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 Final heat treatment 1 7 Decarburization 1 8 Mechanical properties 1ii blankBST77:1980 BSI 02-2000 1 NOTE 1Attention is drawn to the fact that this Br
6、itishStandard does not come into effect until3 months 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 the effective date. NOTE 2Tube of the same composition at lower strength levels is covered by
7、BS T53 (for tube of outside diameter not less than12.5mm) and BS T76, and at a higher strength level by BST60 (for tube of maximum thickness8mm). 1 Inspection and testing procedure 1.1 General. This BritishStandard shall be used in conjunction with sections1 and2 of the latest issue of BS T100. 1.2
8、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 manufactured by an electric process. 3 Chemical composition The steel shall contain: 4 Surface dressing The steel shall be overall
9、 dressed. 5 Condition The tube shall be supplied in the finally heat treated condition. 6 Final heat treatment The final heat treatment shall consist of the following: a) Hardening. Heat uniformly at a temperature between870 C and910 C, followed by quenching in oil or water. b) Tempering. Heat unifo
10、rmly at a temperature of not less than520 C, followed by cooling in a suitable manner. 7 Decarburization The depth of decarburization, at either of the surfaces, shall be not greater than0.1mm or2% of the nominal thickness, whichever is the lesser. 8 Mechanical properties 8.1 Tensile test. The mecha
11、nical properties obtained from test pieces, selected, prepared and tested in accordance with the relevant requirements of BS T100, shall be as follows. 8.2 Hardness test. The hardness of the tube shallbe: 255min./321max.HB or 270min./340max.HV Element % min. max. Carbon Silicon Manganese Phosphorus
12、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 % proof stress Tensile strength Elongation min. min. max. min. MPa (= N/mm 2 ) MPa (= N/mm 2 ) MPa (= N/mm 2 ) % 700 900 1100 10 NOTEInformation on SI units is given in BS3763 “The International Sys
13、tem of units (SI)” and BS350 “Conversion factors and tables”.BS T77:1980 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 and at the international le
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