1、BRITISH STANDARD AEROSPACE SERIES CONFIRMED AUGUST 1985 BS 2S 149: 1976 (Superseding BSS149) Incorporating Amendment No. 1 Specification for 1.75% nickel- chromium- molybdenum steel bars for the manufacture of forged bolts and forged nuts UDC 629.7:669.15242628 194 422:621.882.2/.3BS2S149:1976 This
2、British Standard, having been prepared under the directionof the Aerospace Standards Committee,was published underthe authority ofthe Executive Board on 30 November 1976 BSI 01-2000 The following BSI references relate to the work on this standard: Committee reference ACE/15 Draft for comment 75/7499
3、8 DC ISBN 0 580 09510 X 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 obligations. Summary of pages
4、This document comprises a front cover, an inside front cover, pages i and ii, page 1 and abackcover. 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 publicat
5、ion Amd. No. Date of issue Comments 6837 November 1991 Indicated by a sideline in the marginBS2S149:1976 BSI 01-2000 i Contents Page 1 Inspection and testing procedure 1 2 Manufacture 1 3 Chemical composition 1 4 Surface dressing 1 5 Condition 1 6 Heat treatment 1 7 Mechanical properties 1 8 Grain s
6、ize 1ii blankBS2S149:1976 BSI 01-2000 1 NOTEThe requirements for the finished bolts and nuts are given in the relevant specifications for those products, such as those in the “A” series of British Standards. 1 Inspection and testing procedure 1.1 General. This British Standard shall be used in conju
7、nction with sections 1 and 9 of the latest issue of BS S 100. 1.2 Sulphur printing or deep etching tests. Onesample shall be taken from each ingot for sulphur printing or deep etching tests. 1.3 Ultrasonic examination. Billets shall be subjected to ultrasonic examination. 2 Manufacture The material
8、shall be manufactured by an electric process. 3 Chemical composition The steel shall contain: 4 Surface dressing The material shall be overall dressed. 5 Condition 5.1 Bar in straight lengths. Bar delivered in straight lengths shall be supplied annealed and either cold drawn or centreless ground. 5.
9、2 Bar in coil. Bar delivered in coil shall be supplied spheroidized, cold drawn and suitably coated for cold forging. 6 Heat treatment The final heat treatment applicable to bolts and nuts from this material and to their representative test samples shall consist of the following: a) Hardening. Heat
10、at a temperature of840 C and 870 C, followed by cooling in oil. The tolerance on the chosen temperature shall be 10 C. b) Tempering. Heat uniformly at a temperature between 450 C and 660 C, followed by cooling in air. 7 Mechanical properties 7.1 Hardening test. The hardness shall be not lessthan 500
11、 HV. 7.2 Tests in the condition of supply. Material delivered in the condition specified in 5.1 or 5.2, as appropriate, shall comply with the following requirements. NOTEMPa = N/mm 2 . Information on SI units is given in BS3763 “TheInternational System of units (SI)” and BS 350 “Conversion factors a
12、nd tables”. 8 Grain size The grain size shall be determined in accordance with BS 4490 “Methods for the determination of the austenitic grain size of steel”, method 3 or method 5. The grain size shall be no. 5 or finer and no grain shall be coarser than no. 3. Element % min. max. Carbon 0.38 0.43 Si
13、licon 0.20 0.35 Manganese 0.65 0.85 Phosphorus 0.025 Sulphur 0.020 Chromium 0.70 0.90 Molybdenum 0.20 0.30 Nickel 1.65 2.0 Bar in straight lengths Bar in coil Tensile strength (max.) (MPa) 800 710 or Hardness (max.) 235 HB BS 2S 149: 1976 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsI
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