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1、BRITISH STANDARD BS 970-3:1991 Incorporating Amendment Nos. 1 and 2 Specification for Wrought steel for mechanical and allied engineering purposes Part 3: Bright bars for general engineering purposes BS 970-3:1991 This British Standard, having been prepared under the direction of the Iron and Steel
2、Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 20 December 1991 BSI 11-1998 First published July 1941 Second edition October 1942 Third edition March 1947 Fourth edition January 1955 Fifth edition July 1971 Sixth edition December 1991 Th
3、e following BSI references relate to the work on this standard: Committee reference ISM/31 Draft for comment 91/46105 DC ISBN 0 580 1 9999 1 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Iron and Steel Standards Policy Committee (ISM/-
4、) to Technical Committee ISM/31, upon which the following bodies were represented: Associated Offices Technical Committee British Chain Manufacturers Association British Coal Corporation British Forging Industry Association British Industrial Fasteners Federation British Railways Board British Steel
5、 Industry Cold Rolled Sections Association Department of Trade and Industry (National Physical Laboratory) Engineering Industries Association Federation of British Engineers Tool Manufacturers Lloyds Register of Shipping Ministry of Defence National Association of Steel Stockholders Road Vehicle Spr
6、ing Society Society of Motor Manufacturers and Traders Limited Stainless Steel Fabricators Association of Great Britain Amendments issued since publication Amd. No.DateComments 7227September 1992 8974November 1995 Indicated by a sideline in the margin BS 970-3:1991 BSI 11-1998i Contents Page Committ
7、ees responsible Inside front cover Forewordiii 1Scope1 2Definitions and symbols1 3Information and requirements to be agreed and to be documented2 4General2 5Steelmaking process and casting methods3 6Dimensional tolerances3 7Selection and preparation of test samples4 8Test methods and test results5 9
8、Chemical composition6 10Mechanical properties6 11Retests8 12Freedom from defects8 13Marking9 Appendix A Options30 Table 1 Tolerances for cold drawn bars3 Table 2 Tolerances for turned bars4 Table 3 Tolerances for precision ground bars4 Table 4 Straightness tolerances4 Table 5 Maximum limits on resid
9、ual elements6 Table 6 Permitted variations of product analysis from specified range6 Table 7 Rounds, squares and hexagons in sizes from 10 mm up to and including 100 mm diameter or across flat: maximum permissible surface defects8 Table 8 Flats greater than 105 mm wide in free-cutting, semi-free-cut
10、ting and carbon steels: maximum permissible surface defects9 Table 9 Flats greater than 105 mm wide in hot and cold forging steels and low alloy steels: maximum permissible defect depths9 Table 10 Flats equal to or less than 105 mm wide in free-cutting, semi-free-cutting and carbon steels: maximum p
11、ermissible defect depths10 Table 11 Flats equal to or less than 105 mm wide in hot and cold forging steels and low alloy steels: maximum permissible defect depths10 Table 12 Chemical composition: free-cutting steels10 Table 13 Chemical composition: carbon and carbon manganese steels11 Table 14 Chemi
12、cal composition: case hardening steels (carbon and carbon manganese steels)11 Table 15 Chemical composition: alloy case hardening steels11 Table 16 Chemical composition: alloy direct hardening steels12 Table 17 Chemical composition: ferritic and martensitic stainless and heat resisting steels12 Tabl
13、e 18 Chemical composition: Austenitic stainless and heat resisting steels13 Table 19 Mechanical properties for free-cutting steels14 BS 970-3:1991 ii BSI 11-1998 Page Table 20 Mechanical properties for carbon and carbon manganese steels15 Table 21 Mechanical properties for alloy steels18 Table 22 Me
14、chanical properties for case hardening steels23 Table 23 Heat treatment and mechanical properties for ferritic and martensitic stainless and heat resisting steels24 Table 24 Softening treatment and mechanical properties for austenitic stainless and heat resisting steels in the finally softened condi
15、tion26 Table 25 Mechanical properties for austenitic stainless steels in the cold drawn condition27 Table 26 Mechanical properties for austenitic stainless steels in the softened and finally cold drawn condition27 Table 27 Normalizing for carbon and carbon manganese steels27 Table 28 Hardening and t
16、empering parameters for free-cutting, carbon and carbon manganese, and alloy steels28 Table 29 Reference symbols for tensile strength ranges of hardened and tempered material29 Publication(s) referred toInside back cover BS 970-3:1991 BSI 11-1998 iii Foreword This Part of BS 970 has been prepared un
17、der the direction of the Iron and Steel Standards Policy Committee. It supersedes those clauses concerned with bright finished bars in BS 970-1:1983, which is withdrawn. Technical Committee ISM/31 has decided that requirements for bars supplied in the bright cold finished condition should be withdra
18、wn from BS 970-1:1983 to appear in a separate standard for the sake of clarity and as a preparatory step towards a European Standard for this product range. This Part of BS 970 specifies the requirements for bright cold finished bars in carbon, carbon manganese, alloy, free-cutting and stainless ste
19、els supplied in straight lengths. 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
20、 of pages This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 30, an inside back cover 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
21、 cover. iv blank BS 970-3:1991 BSI 11-19981 1 Scope This Part of BS 970 specifies requirements for carbon and carbon manganese, alloy, free-cutting and stainless steels normally supplied in the bright cold finished condition. It is only applicable to steels supplied in straight lengths. In addition
22、to the definitive requirements, this Part of BS 970 also requires the items detailed in clause 3 to be documented. For compliance with this Part of BS 970, both the definitive requirements and the documented items have to be satisfied. Special ordering options to be called up as required by the purc
23、haser are included in appendix A. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions and symbols 2.1 Definitions For the purposes of this Part of BS 970 the following definitions apply. 2.1.1 bright cold drawn bars bars of various cross
24、-sectional shapes obtained, after descaling, by drawing of hot rolled bars or rod, through a die (cold deformation without removing material) NOTEThis operation gives the product special features with respect to shape, dimensional accuracy and surface finish. In addition, the process causes cold wor
25、king of the product, which can be eliminated by subsequent heat treatment. Products in lengths are delivered straightened regardless of size. 2.1.2 bright turned bars bars of circular cross section having the special features of drawn product concerning shape, dimensional accuracy and bright surface
26、 finish with the additional benefit of metal removal on decarburization and surface defectiveness produced by turning 2.1.3 precision ground bars drawn or turned bars of circular cross section given an improved surface finish and dimensional accuracy by grinding or grinding and polishing 2.1.4 annea
27、ling heat treatment consisting of heating and soaking at a suitable temperature followed by cooling under conditions such that, after return to ambient temperature, the metal will be in a structural state closer to that of equilibrium NOTEThe heat treatments in 2.1.4 to 2.1.7 can be carried out eith
28、er before or after cold conversion and can result in surface discolouration. 2.1.5 normalizing heat treatment consisting of austenitizing followed by air cooling to refine the metallurgical structure (See note to 2.1.4.) 2.1.6 stress relieving heat treatment including heating and soaking at a suitab
29、le temperature followed by cooling at an appropriate rate in order to relieve internal stresses without substantially modifying the structure (See note to 2.1.4.) 2.1.7 hardening and tempering heat treatment including heating to a temperature above the upper critical temperature followed by rapid co
30、oling by means of a suitable quenching medium and subsequent reheating to a temperature below the lower critical temperature (See note to 2.1.4.) 2.1.8 ruling section the equivalent diameter of that portion of the product at the time of heat treatment that is most important in relation to mechanical
31、 properties 2.1.9 limiting ruling section the largest diameter in which certain specified mechanical properties are achieved after a specified heat treatment 2.1.10 equivalent diameter the diameter of a hypothetical bar of infinite length of uniform circular cross section which, if subjected to the
32、same cooling conditions as the product, i.e. same initial and final temperature and same cooling medium, would have a cooling rate at its axis equivalent to that at the slowest cooling position in the product or relevant part 2.1.11 test sample a sufficient quantity of material taken from the sample
33、 product for the purpose of producing one or more test pieces 2.1.12 test piece part of the test sample, with the specified dimensions, machined or unmachined, brought to the required condition for submission to a given test BS 970-3:1991 2 BSI 11-1998 2.2 symbols the symbols used in this Part of BS
34、 970 are given in 1.3 of BS 970-1:1991 3 Information and requirements to be agreed and to be documented 3.1 Information to be supplied by the purchaser The following information to be supplied by the purchaser shall be fully documented. Both the definitive requirements specified throughout this Part
35、 of BS 970 and the following documented items shall be satisfied before a claim of compliance with this Part of BS 970 can be made and verified: a) details of the form of section, size, length and quantity; b) the tolerances required on sections (see Table 1 to Table 4); c) the grade of steel requir
36、ed (see Table 5 and Table 6 and Table 12 to Table 28); d) the tolerances required on length; e) surface condition of supply (see clause 12 and Table 7 to Table 11); f) heat treatment condition together with any physical properties required (see Table 19 to Table 28); 3.2 Options If the purchaser wis
37、hes to take up any of the optional requirements given in this Part of BS 970 (see appendix A), such requirements shall be specified at the time of the enquiry and/or order. In the absence of such information, the manufacturer shall supply in accordance with the basic specification. 3.3 Items for agr
38、eement 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 this Part of BS 970 and the following documented items shall be satisfied before a claim of compli
39、ance with the standard can be made and verified. a) If controlled magnetic properties are required they shall be agreed at the time of enquiry and/or order (see 4.3.2). b) If bars shall be supplied with special corrosion protection it shall be specified and agreed at the time of enquiry and/or order
40、 (see 4.6). c) If any particular type of deoxidation is required it shall be agreed at the time of enquiry and/or order (see 5.1). d) If closer dimensional tolerances than those given in Table 1 to Table 4 are required they shall be agreed at the time of enquiry and/or order (see 6.4). e) Results ba
41、sed on test bar sizes of 13 mm or 29 mm shall be agreed at the time of enquiry and/or order (see 7.3.1 and 10.4). f) If mechanical properties other than those in a longitudinal direction are required values shall be agreed at the time of enquiry and/or order (see 7.4.2). g) If a particular grain siz
42、e range is required it shall be supplied and the method of measurement agreed at the time of enquiry and/or order (see 8.5). h) If restrictions on certain elements in the chemical composition ranges are required this shall be agreed at the time of enquiry and/or order (see 9.1). i) If controlled sul
43、fur and phosphorus ranges other than those specified in Table 12 to Table 18 are required they shall be agreed at the time of enquiry and/or order (see 9.1). j) If specific non-destructive testing is required the inspection technique and the inspection limits shall be agreed at the time of enquiry a
44、nd/or order (see 12.1 and 12.3.1.4). k) If specific cleanness requirements are required the relevant standard criteria shall be agreed at the time of enquiry and/or order (see 12.2). l) If a maximum decarburization limit is required the level shall be agreed at the time of enquiry and/or order and m
45、easured in accordance with BS 6617-1 and BS 6617-2 (see 12.4). m) If end stamping or colour coding is required it shall be agreed at the time of enquiry and/or order (see clause 13). 4 General 4.1 Steel products Steel products shall comply with the specific requirements of this Part of BS 970 and wi
46、th the specific requirements applicable to the grade concerned. Where any of the options given in appendix A are called up at the time of the enquiry and/or order, the steel products shall, comply with the requirements of any such options. BS 970-3:1991 BSI 11-19983 4.2 Carbon, carbon manganese, fre
47、e-cutting and alloy steels Where mechanical properties are obtained by heat treatment, the treatment given to the test bars and to material required in the finally heat treated condition shall be as given in Table 19 to Table 28. Unless otherwise specified at the time of enquiry and/or order bars su
48、pplied in the non-heat treated condition shall not be hardness tested. (See also option A.1.) 4.3 Stainless steels 4.3.1 Ferritic steels When bright bars are supplied in the hardened and tempered condition, the heat treatment shall be given either before or after any cold sizing NOTEBright bars of f
49、erritic steel supplied in the softened condition can be treated before or after any cold sizing. 4.3.2 Austenitic steels When bright bars are supplied in the softened condition the heat treatment shall be given before drawing, turning or grinding. NOTEIf controlled magnetic properties are required, see3.3a). 4.3.3 Martensitic steels Bright bars of martensitic steels shall be supplied in the condition given in Table 23. 4.4 Specific requirements of Table 12 to Table 28 The specific requirements given in Table 12 to Tab