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1、BRITISH STANDARD BS 7814:1995 Specification for Bolts and screws incorporating either underhead locking or anti-rotation features UDC 681.3:621.39 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:20:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7814:1995 Th
2、is British Standard, having been prepared under the direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes into effect on 15 December 1995 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference GME/9 Dr
3、aft for comment 94/704978 DC ISBN 0 580 24520 9 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee GME/9, Bolts, nuts and accessories, upon which the following bodies were represented: BEAMA Ltd. British Constructional Steel
4、work Association Ltd. British Industrial Fasteners Federation British Steel Industry British Steel Industry (Wire Section) Gauge and Tool Makers Association National Association of Fastener Stockholders Society of Motor Manufacturers and Traders Ltd. Washer Manufacturers Association of Great Britain
5、 The following bodies were also represented in the drafting of the standard, through subcommittees and panels: British Turned-parts Manufacturers Association Institute of Metal Finishing Metal Finishing Association National Centre of Tribology Stainless Steel Fabricators Association of Great Britain
6、 Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:20:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7814:1995 BSI 08-1999i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Nor
7、mative reference1 3Information and requirements to be agreed and to be documented1 4Materials1 5Mechanical properties1 6Test methods2 7Marking2 Figure 1 Examples of marking on hexagon bolts and screws3 Figure 2 Examples of marking on hexagon socket head3 Figure 3 Left-hand thread marking3 Table 1 Eq
8、uivalent property class of fastener from BS EN 20898-1:1992 for material selection1 Table 2 Additional mechanical properties for bolts and screws with underhead locking or anti-rotation features1 Table 3 Surface hardness for bolts and screws with locking or anti-rotation features2 Table 4 Marking sy
9、mbols2 List of referencesInside back cover Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:20:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7814:1995 ii BSI 08-1999 Foreword This British Standard has been prepared by Technical Committee GME/9. It includes
10、mechanical properties for bolts and screws with either underhead locking or anti-rotation features. 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
11、does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated.
12、 This will be indicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:20:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7814:1995 BSI 08-19991 1 Scope This British Standard specifies the materials, mechani
13、cal properties and marking requirements for bolts and screws incorporating either underhead locking or anti-rotation features when tested at an ambient temperature between 15 C and 30 C. It applies to bolts and screws: a) with ISO metric M2 to M20 threads conforming to BS 3643-2:1981; b) with mechan
14、ical properties 80, 90 or 1001) as appropriate; c) for use within the temperature range 50 C to + 250 C. As the decarburization of any underhead locking or anti-rotation feature will seriously impair its intended function, partial or complete decarburization as given in BS EN 20898-1:1992 does not a
15、pply to this standard. There is instead a requirement for carbon restoration to ensure that no decarburization of the locking or anti-rotation feature takes place during the heat treatment process. NOTEPerformance at temperatures outside the operating range is not within the requirements of this sta
16、ndard. 2 Normative reference This British Standard incorporates by dated or undated reference provisions from other publications. These normative references are made at the appropriate places in the text and the cited publications are listed on the inside back cover. For dated references, only the e
17、dition cited applies; any subsequent amendments to or revisions of the cited publication apply to this standard only when incorporated in the reference by amendment or revision. For undated reference, the latest edition of the cited publication applies, together with any amendments. 3 Information an
18、d requirements to be agreed and to be documented The following items to be agreed between the contracting parties, which are specified in the clauses referred to, shall be fully documented. Both the definitive requirements specified throughout the standard and the following documented items shall be
19、 satisfied before a claim of compliance with a standard can be made and verified. a) if an anti-rotation feature is required the hole diameter in the component into which the knurl bolt is assembled shall be agreed at the time of enquiry and/or order (see 5.5). b) if a particular surface treatment a
20、pplied to bolts and screws with underhead locking or anti-rotation features is required it shall be agreed at the time of enquiry and/or order (see 5.6). 4 Materials The steels used to produce bolts and screws with underhead locking or anti-rotation features shall be in accordance with those specifi
21、ed in Table 2 of BS EN 20898-1:1992 for the equivalent property class of fastener as stipulated in Table 1. Table 1 Equivalent property class of fastener from BS EN 20898-1:1992 for material selection 5 Mechanical properties 5.1 General The mechanical properties of bolts and screws with underhead lo
22、cking or anti-rotation features shall be in accordance with the following: Table 2; ISO 898-7:1992; clause 5 of BS EN 20898-1:1992, with the exception of 5.6 and 5.11, for the equivalent property classes stipulated in Table 1. Table 2 Additional mechanical properties for bolts and screws with underh
23、ead locking or anti-rotation features 1) With the exception of surface hardness and strength under wedge loading the mechanical properties 80, 90 and 100 are in line with the respective mechanical properties of property classes 8.8, 9.8 and 10.9 of BS EN 20898-1:1992 Mechanical property class Equiva
24、lent property class of fastener from BS EN 20898-1:1992 808.8 909.8 10010.9 or 10.9 Mechanical propertyClauseTest method Wedge tensile strength 5.2See 8.4 of BS EN 20898-1:1992 Decarburization and carbon restoration 5.36.1 Surface hardness5.46.2 Anti-rotation feature 5.5 Surface treatment and embrit
25、tlement 5.6 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:20:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7814:1995 2 BSI 08-1999 5.2 Wedge tensile strength Bolts and screws with underhead locking or anti-rotation features shall be heat treated to achie
26、ve the minimum tensile strength specified in Table 3 of BS EN 20898-1:1992, for the equivalent property class as stipulated in Table 1, when tested against a 6 wedge. 5.3 Decarburization and carbon restoration In order to eliminate any decarburization during heat treatment, the carbon potential of t
27、he atmosphere inside the furnace where the heat treatment takes place shall be maintained at a level slightly in excess of the carbon content of the steel from which the bolt or screw has been manufactured. There shall be no decarburization. Carbon enrichment of the surface of a bolt or screw up to
28、a depth of 0.1 mm maximum for the size range M2 to M12 inclusive and 0.25 mm maximum for the size range M14 to M20 inclusive shall be allowed as the result of the carbon restoration process. NOTEThe decarburization specified in BS EN 20898-1:1992 is not applicable to this standard as it would impair
29、 the performance of any underhead locking or anti-rotation feature. 5.4 Surface hardness The minimum tempering temperature specified in BS EN 20898-1:1992 for the equivalent property classes stipulated in Table 1 shall apply to bolts and screws in this standard. When tested in accordance with 6.2 th
30、e surface hardness of bolts and screws with underhead locking or anti-rotation features shall be as given in Table 3. Table 3 Surface hardness for bolts and screws with locking or anti-rotation features 5.5 Anti-rotation feature Bolts with an anti-rotation feature, commonly known as knurl bolts, sha
31、ll without permanent deformation of the anti-rotation feature when viewed at 10 times magnification, produce a mating form in the component to which they are assembled. The hole diameter in the component into which the knurl bolt is assembled shall be agreed between the customer and supplier in orde
32、r to take account of such variations as material hardness and length of engagement see 3 a). 5.6 Surface treatment and embrittlement The surface treatment applied to bolts and screws with underhead locking or anti-rotation features shall be agreed between the customer and supplier see 3 b). NOTEAs f
33、asteners to this standard are susceptible to embrittlement non-electrolytic coatings should be the preferred option. 6 Test methods 6.1 Decarburization test Longitudinal sections shall be taken through the axis at a distance of approximately one times the nominal thread diameter from the end of the
34、bolt or screw. The sections shall be suitably mounted and prepared for metallographic examination at not less than 100 times magnification. Prior to the metallographic examination the prepared specimen shall be etched in 2 % nital solution. 6.2 Surface hardness test The surface hardness shall be mea
35、sured using the Vickers hardness testing procedure specified in ISO 6507-1:1982. The surface hardness shall be measured on the head or end of the bolt or screw after the removal of any surface treatment and any suitable preparation of the specimen. NOTECare should be taken to remove as little materi
36、al as possible during the preparation of the specimen. For referee purposes a micro-hardness instrument with a Vickers indenter and a 300g load shall be used. In such cases, measurements shall be made on the thread profile of a suitably prepared longitudinal metallographic specimen. 7 Marking 7.1 Sy
37、mbols Marking symbols are shown in Table 4. Table 4 Marking symbols 7.2 Identification Bolts and screws with underhead locking or anti-rotation features and with nominal thread diameters of 5 mm or greater shall be marked with the appropriate marking symbol for the mechanical property class of the f
38、astener. The markings shall be by indenting or embossing on the top of the head or indenting on the side of the head, see Figure 1 and Figure 2. Mechanical property classsurface hardness (Hv5) 80270 to 370 90300 to 390 100340 to 430 Mechanical property class8090100 Marking symbol8090100 Licensed Cop
39、y: London South Bank University, London South Bank University, Fri Dec 08 11:20:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7814:1995 BSI 08-19993 7.3 Marking of left-hand threads Bolts and screws with underhead locking or anti-rotation features with nominal thread diameter of 5 mm or greater a
40、nd left hand thread shall be marked with the symbol shown in Figure 3, either on the top of the head or the point. 7.4 Trade (identification) marking The trade (identification) marking of the manufacturer shall be marked on all products which are required to be marked with the mechanical property cl
41、ass marking symbol. Figure 1 Examples of marking on hexagon bolts and screws Figure 2 Examples of marking on hexagon socket head cap screws Figure 3 Left-hand thread marking Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:20:37 GMT+00:00 2006, Uncontrolled Co
42、py, (c) BSI 4 blank Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:20:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7814:1995 BSI 08-1999 List of references (see clause 2) Normative references BSI publication BRITISH STANDARDS INSTITUTION, London BS 3643,
43、 ISO metric screw threads. BS 3643-2:1981, Specification for selected limits of size. BS EN 20898, Mechanical properties of fasteners. BS EN 20898-1:1992, Bolts, screws and studs. ISO publications International Organization for Standardization (ISO), Geneva. All publications are available from BSI C
44、ustomer Services. ISO 898, Mechanical properties of fasteners. ISO 898-7:1992, Torsional test and minimum torques for bolts and screws with nominal diameters 1 mm to 10 mm. ISO 6507, Metallic materials Hardness test Vickers test. ISO 6507-1:1982, HV 5 to HV 100. Licensed Copy: London South Bank Univ
45、ersity, London South Bank University, Fri Dec 08 11:20:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7814:1995 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on st
46、andards in Europe and at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quali
47、ty of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel: 020 8996 9000. Fax: 020 8996 7400
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