1、BRITISH STANDARD BS4276:1968 Incorporating Amendment No.1 Specification for Hard metal for wire, bar and tube drawing diesBS4276:1968 This BritishStandard, having been approved by the MechanicalEngineering IndustryStandards Committeeand endorsed by theChairman of the EngineeringDivisional Council,wa
2、s published undertheauthority of the GeneralCouncil on 21February1968 BSI12-1999 The following BSI references relate to the work on this standard: Committee reference MEE/155 Draft for comment 66/8963 ISBN 0 580 00075 3 Co-operating organizations The Mechanical Engineering Industry Standards Committ
3、ee, under whose supervision this BritishStandard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Associated Offices Technical Committee Institution of Civil Engineers Association of Consulting Engineers Institution of G
4、as Engineers Association of Mining Electrical and Institution of Heating and Ventilating Mechanical Engineers Engineers Board of Trade Institution of Mechanical Engineers* British Chemical Plant Manufacturers Institution of Mechanical Engineers Association (Automobile Division) British Compressed Ai
5、r Society Institution of Production Engineers* British Electrical and Allied Manufacturers Locomotive and Allied Manufacturers Association Association of Great Britain British Gear Manufacturers Association London Transport Board British Internal Combustion Engine Machine Tool Trades Association Man
6、ufacturers Association Ministry of Defence British Iron and Steel Federation* Ministry of Labour (H.M. Factory Inspectorate) British Mechanical Engineering Federation Ministry of Power British Pump Manufacturers Association Ministry of Public Building and Works Crown Agents for Oversea Governments a
7、nd Ministry of Technology National Administrations Engineering Laboratory Electricity Council, the Central Electricity Ministry of Transport Generating Board and the Area Boards in National Coal Board England and Wales. National Physical Laboratory Engineering Equipment Users Association (Ministry o
8、f Technology) Gas Council Radio Industry Council Institute of Marine Engineers Royal Institute of British Architects The scientific and industrial organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the prepa
9、ration of this BritishStandard: British Hard Metal Association Institute of Iron & Steel Wire Manufacturers British Non-Ferrous Metals Federation British Non-Ferrous Metals Federation High Conductivity Copper Group Amendments issued since publication Amd. No. Date of issue Comments 7746 August1993 I
10、ndicated by a sideline in the marginBS4276:1968 BSI 12-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Method of manufacture 1 3 Designation 1 4 Hardness 1 5 Hardness test 1 6 Transverse rupture strength 1 7 Cobalt content 1 8 Impurities 1 9 Grain size 2 10
11、 Porosity 2 11 Defects 2 Figure 1 Carbide grain size chart for1 to10 micrometres, at1500 dia. 3 Table 1 Hard Metal designated in accordance with groups of hardness 2BS4276:1968 ii BSI 12-1999 Foreword This standard makes reference to the following BritishStandards: BS427, Method for Vickers hardness
12、 test Part1: Testing of metals Part2: Verification of the testing machine. BS3821, Finished Hard Metal dies for drawing round wire. BS5600, Powder metallurgical materials and products Section4.14 Metallographic determination of porosity and uncombined carbon. This BritishStandard has been prepared u
13、nder the authority of the Mechanical Engineering Industry Standards Committee and with the fullest co-operation of die users and manufacturers, and the manufacturers of wire drawing machinery. The standard specifies eight types of Hard Metal grade for use in wire, bar and tube drawing dies and lays
14、down the hardness, composition and grain size required for the Hard Metal for these grades. Since information is not available which would enable optimum combinations of these three properties to be specified, the limits in this specification are necessarily broad and it should be regarded as an int
15、erim standard against which grades of Hard Metal can be recognized and checked. With its help, data can be compiled which relates hardness, etc., with performance so that a future revision can specify optimum grades more precisely for particular applications. The production of the standard was refer
16、red to in BS3821:1964, “Finished Hard Metal dies for drawing round wire” but the scope of this standard is wider than BS3821 (see Clause1). A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct applicat
17、ion. 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, pages1 to4, an inside back cover and a back cover. This standard has been updated (see copyright date) and m
18、ay have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS4276:1968 BSI 12-1999 1 1 Scope 1.1 This BritishStandard specifies requirements for Hard Metal grades generally used in the manufacture of dies for cold drawing wire, bar and tube in ferrou
19、s and non-ferrous metals and alloys. 1.2 Special Hard Metal grades in which some or all of the cobalt is present as eta-phase or in which binder metals other than Cobalt are used, are excluded from this specification. 2 Method of manufacture 2.1 The Hard Metal may be produced by either of the follow
20、ing methods: 1) Cold pressing and sintering 2) Hot pressing 2.2 The method of manufacture may be varied at the discretion of the manufacturer. 3 Designation 3.1 The Hard Metal shall be designated in accordance with8 groups of hardness. 3.2 The cobalt content and grain size which controls the hardnes
21、s, together with the other relevant properties, would be expected to fall within the ranges specified against each group of hardness, as given in Table 1. 3.3 Any grade of hard metal supplied shall be designated by the Group Number in Table 1, together with its average hardness and nominal cobalt co
22、ntent. 4 Hardness 4.1 The average hardness of any grade, as nominated by the manufacturer, shall fall within the range specified for each group. 4.2 Any pellet supplied against the specification shall not vary by more than50 points HV above or below the nominated average hardness except for Groups B
23、S6, BS7 and BS8 which shall not vary by more than75 points HV above or below the nominated average hardness when hot pressed. 5 Hardness test 5.1 The hardness test shall be carried out in accordance with BS427-1 and BS427-2 1)using a load of not less than30kgf, not more than50kgf. 5.2 The tests shal
24、l be carried out on the surface of the pellet after removing not less than0.38mm(0.015in) of material. 5.3 The finish of the surface shall be fine enough to give a distinct impression for accurate measurement. 5.4 It must not be expected that different test houses will agree on any specific hardness
25、 determination to within plus or minus2% (BS427-2 1) ). 6 Transverse rupture strength 6.1 The figures shown in Table 1 represent the transverse rupture strength as determined in accordance with the recommended practice of the American Society for Testing and Materials (ASTM B.406-63T). 6.2 Normally
26、transverse rupture testing is part of a routine long-term control in the manufacture of Hard Metal. 6.2.1 It is not necessarily applied to every batch of Hard Metal produced and is not, therefore, acceptance criteria for Hard Metal but is intended as a useful indication of toughness. 7 Cobalt conten
27、t 7.1 The cobalt content may vary in accordance with the figures shown in Table 1 against each group. 7.2 The permissible divergence for the nominal cobalt content figure, as specified by the manufacturer, which takes into account inaccuracies in determination, shall be as set out below: 7.3 The cob
28、alt figure shall be determined from the sintered Hard Metal piece. Care shall be taken to ensure that a sufficiently large sample is taken so as to be representative of the whole piece. 8 Impurities 8.1 The total impurities, excluding elements or carbides intentionally added, shall not exceed0.75% a
29、nd the individual impurities shall not exceed the following: The amount of free carbon present shall be ascertained in accordance with the method in4.4 of BS5600-4.14:1980 and shall not exceed the level designated as CO 2 . 1) BS427, “Method for Vickers hardness test”. Part1, “Testing of materials”.
30、 Part2, “Verification of the testing machine”. Nominal cobalt content Cold pressed and sintered Hot pressed Up to10% Over10% 0.5%+0.25% 0.75%+0.5% 1.00%+0.25% 1.25%+0.5% Iron 0.2% max.BS4276:1968 2 BSI 12-1999 8.2 Any other individual impurities shall not exceed0.1%. 8.3 Nickel shall not exceed2% of
31、 the nominal cobalt content and shall not be included in the total amount of impurities(0.75% max.). 9 Grain size 9.1 The grain size shown in Table 1 shall be the predominant grain size of at least60% of the microscopic field. 9.2 For grain size measurement a convenient method is the use of the atta
32、ched Miller diagram (see Figure 1). 10 Porosity The pellet in that part which deforms and sizes the product shall be free from inherent porosity which would affect performance during its useful life. 11 Defects The Hard Metal shall be free from eta-phase and from any undue amount of cobalt segregati
33、on. Table 1 Hard metal designated in accordance with groups of hardness Group number Range of average hardness Range of nominal cobalt Range of predominant grain size Minimum density Range of average transverse rupture BS1 BS2 BS3 BS4 BS5 BS6 BS7 BS8 HV 1750 & over 17001745 16001695 15001595 1400149
34、5 13001395 12001295 11001195 % 46 4“7 4“7 5“7“ 79“ 8“12“ 1014 1117 micrometres “ 1 “ 1“ “ 2 13 15 15 15 15 g/cm 3 14.80 14.65 14.65 14.60 14.40 14.10 13.95 13.65 N/mm 2 13902085 13902085 16202085 17752315 18552395 20852470 21602550 23152700 tonf/in 2 90135 90135 105135 115150 120155 135160 140165 15
35、0175BS4276:1968 BSI 12-1999 3 (Reproduced from “Metal Progress” April,1953). (Originally in the General Motors Book of Standards serial G.M.4454-P, May1950). Figure 1 Carbide grain size chart for1 to10 micrometres, at1500 dia. (1micrometre=0.00003937in)4 blankBS4276:1968 BSI 12-1999 BritishStandards
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