1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 131-6:1998 ICS 77.040.
2、10 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Notched bar tests Part 6: Method for precision determination of Charpy V-notch impact energies for metalsThis British Standard, having been prepared under the direction of the Engineering Sector Committee, was published under
3、the authority of the Standards Committee and comes into effect on 15 December 1998 BSI 1998 First published February 1990 Second edition December 1998 The following BSI references relate to the work on this standard: Committee reference ISE/NFE/4/4 Draft for comment 97/700423 DC ISBN 0 580 28213 9 B
4、S 131-6:1998 Amendments issued since publication Amd. No. Date Text affected Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee ISE/NFE/4, Mechanical testing of metals, to Subcommittee ISE/NFE/4/4, Toughness testing, upon wh
5、ich the following bodies were represented: AEA Technology BEAMA Ltd. Electricity Association GAMBICA (BEAMA Limited) Institute of Materials Lloyds Register of Shipping Ministry of Defence National Physical Laboratory Railtrack Society of British Aerospace Companies Limited UK Steel Association Unite
6、d Kingdom Accreditation Service Welding Institute Coopted membersBS 131-6:1998 BSI 1998 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Normative references 1 3 Definitions 1 4 Principle 1 5 Testing machine 1 6 Test piece preparation 1 7 Calibration 5 8 Test procedu
7、re 5 9 Test report 6 Annex A (informative) Measurement of lateral expansion by means of a gauge 8 Bibliography 8 Figure 1 Features of Charpy test piece 2 Figure 2 Types of hammer 3 Figure 3 Comparison between 8 mm and 2 mm striker designs 3 Figure 4 Location of areas of test piece for identification
8、 markings 4 Figure 5 Broken halves of the Charpy test piece positioned to illustrate the lateral expansion 7 Figure A.1 Typical lateral expansion gauge 9 Table 1 Dimensions, tolerances and surface finish of test pieces 4ii BSI 1998 BS 131-6:1998 Foreword This part of BS 131 has been prepared by Subc
9、ommittee ISE/NFE/4/4. It supersedes BS 131-6:1989 which is withdrawn. It is intended that this part of this British Standard should be used in conjunction with BS 131-7, Notched bar tests Part 7: Specification for verification of the test machine used for precision determination of Charpy V-notch im
10、pact energies for metals. Results from the calibration,which are recorded on the certificate of calibration, are needed for the determination, using this part of BS 131. BS 131-6 and BS 131-7 are designed to satisfy the demand from sectors of British industry for a more stringent standard of Charpy
11、testing appropriate to the needs of specific applications where a more precise measure of Charpy impact energy is required. This part defines a method of precision Charpy impact testing. The requirements of quality control impact testing will continue to be met by BS EN 10045-1 and BS EN 10045-2, or
12、 BS 131-1, BS 131-4 and BS 131-5 unless BS 131-6 and BS 131-7 are specified in the product standard. It should be noted that no trustworthy relationship between the energies absorbed in breaking test pieces of different dimensions has been found, and comparison of results is only valid when consider
13、ing test pieces of identical form and dimensions. It has been assumed in the drafting of this standard that the execution of its provisions is entrusted to appropriately qualified and experienced people. WARNING. It is important to note that tests of the type described involve the use of rapidly mov
14、ing test pieces and machine parts. Therefore it is important to consider the safety of machine operators. 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 Sta
15、ndard 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 9 and a back cover. BSI 1998 1 BS 131-6:1998 Method 1 Scope This part of BS 131 describes a method for carrying out a precision C
16、harpy V-notch impact test. 2 Normative references The following normative document contains provisions which, through reference in this text, constitute provisions of this part of this British Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not
17、 apply. For undated references, the latest edition of the publication referred to applies. BS 131-7, Notched bar tests Part 7: Specification for verification of the test machine used for precision determination of Charpy V-notch impact energies for metals. 3 Definitions For the purposes of this part
18、 of BS 131 the following definitions apply. 3.1 compensated machine machine in which correction for the loss in energy of the pendulum due to windage and friction has been made such that on a free half-cycle of swing of the pendulum from the release position the indicated absorbed energy is zero 3.2
19、 non-compensated machine machine in which no correction for loss of energy due to windage and friction has been made NOTE With a machine of this type the indicated absorbed energy on a free half-cycle of swing of the pendulum will have a small positive value. 3.3 test piece terminology (see Figure 1
20、) 3.3.1 width minor dimension in the horizontal plane when placed in the test position, i.e. the distance between the notched face and the opposite unnotched face 3.3.2 height vertical dimension of the test piece when placed in the test position, i.e. the distance across the notched face 3.3.3 lengt
21、h major dimension in the horizontal plane when placed in the test position 3.4 C-type pendulum pendulum in which any portion of the hammer or weighted mass at the lower end of the pendulum and distance greater than L s 2 15 mm from the spindle axis passes between the anvils of the impact test machin
22、e (see Figure 2) NOTE L s is the length of pendulum from centre of strike of pendulum to axis of rotation. 3.5 U-type pendulum pendulum in which the part of the necessary weighted mass at the lower end is designed to pass below and on either side of the test piece anvils of the impact test machine (
23、see Figure 2) 4 Principle A standard notched test piece is fractured with one blow of a swinging pendulum with known energy. The energy absorbed in fracturing the test piece is measured. This represents the Charpy impact energy of the material. NOTE The increase in the specimen thickness may be meas
24、ured. This is designated the lateral expansion of the specimen. 5 Testing machine 5.1 Calibration The machine shall conform to the requirements of BS 131-7. 5.2 Choice of striker The machine shall be equipped with a striker of either the 2 mm tip radius or the 8 mm tip radius design (see Figure 3).
25、The striker to be used shall be as specified in the product standard or agreed and documented at time of order. NOTE Results obtained using the different strikers are known to differ and the relationship is both material and energy dependent. 6 Test piece preparation 6.1 The test piece shall be mach
26、ined such that the metallurgical condition of the material is not affected. At the mid-length position on one face, the test piece shall be notched, the notch having a “V” configuration. The dimensional and surface finish requirements for the test piece shall be as given in Table 1. NOTE When test p
27、ieces are to be heat treated it is recommended that finish machining be carried out after the final heat treatment. 6.2 Identification marks shall be placed outside any area of the test piece that contacts the striking edge, anvils or test piece supports, or which is within 5 mm of the notch (see Fi
28、gure 4).2 BSI 1998 BS 131-6:1998 H = height of test piece W = width of test piece L = length of test piece A = angle of notch R = root radius of notch D = depth below notch a = angle between plane of symmetry of notch and longitudinal axis of test piece b = angle between plane of symmetry of notch a
29、nd face in which notch is cut Figure 1 Features of Charpy test piece BSI 1998 3 BS 131-6:1998 C-type U-type Figure 2 Types of hammer R 8 R 0.25 30 30 8 mm striker ASTM E23 4.0 0.1 4.5 2 mm striker R 2 to 2.5 All dimensions are in millimetres Figure 3 Comparison between 8 mm and 2 mm striker designs4
30、 BSI 1998 BS 131-6:1998 All dimensions in millimetres. NOTE Only the hatched areas and the two ends may be marked. Figure 4 Location of areas of test piece for identification markings Table 1 Dimensions, tolerances and surface finish of test pieces Symbol (see Figure 1) Dimensions Nominal value Tole
31、rance Linear dimensions mm mm D Depth below notch 8 0.025 H Height full size test piece 10 0.075 subsidiary test pieces 7.5 0.075 5.0 0.050 2.5 0.025 L Length 55 21.0 0 R Radius of curvature of root of V-notch 0.25 0.025 W Width 10 0.075 Distance of notch from end of test piece 27.5 0.40 Parallel si
32、de, i.e. taper of test piece 0.075 Angular dimensions 8 (degrees) 8 (degrees) A Angle of V-notch 45 1 a Angle between plane of symmetry of notch and longitudinal axis of test piece 90 2 b Angle between plane of symmetry of notch and face in which notch is cut 90 2 Angle between adjacent sides of tes
33、t piece 90 08 109 Surface finish mm Notched and opposite faces better than 2 Other two faces better than 4 BSI 1998 5 BS 131-6:1998 7 Calibration 7.1 General Prior to any testing, confirm that the machine has been calibrated in accordance with the requirements of BS 131-7 within the previous 12 mont
34、hs. The calibration of measuring apparatus shall be traceable to the National Physical Laboratory either directly or indirectly through a hierarchical chain such as that provided by the United Kingdom Accreditation Service (UKAS) in accordance with the accuracy demanded by the test. 7.2 Daily checks
35、 by the user Immediately prior to use, or daily for a machine in regular use, check the machine in accordance with the requirements of BS 131-7 for the following. a) Windage and friction losses. Without a test piece in position, operate the machine normally and record the absorbed energy value A v1
36、for subsequent use (see 8.2.4). If this exceeds 0.4 % of the initial potential energy, the current calibration certificate is voided and the machine shall not be used for testing to this standard. NOTE If subsequent test results are to be compensated for friction and windage losses, A fw should be d
37、etermined using the method described in BS 131-7. b) Distance between the supports. Check that the distance between the supports is mm. 40 0 +0.05 c) Position of striking edge. The centre of the striking edge shall be within 0.25 mm of the centre of the gap between the test piece supports. d) Soundn
38、ess of contacting surfaces. All test piece contacting surfaces and edges shall be visually examined for defects. An examination shall always be carried out in the event of the pendulum being stopped by a test piece during a test. NOTE The object is to exclude superficial damage which increases the f
39、rictional resistance of the test piece as it passes through the anvil gap during fracture. It is essential that such damage is rectified so that the dimensional requirements of the anvils are met prior to the recommencement of testing. e) If the machine is fitted with a C-type pendulum, check that a
40、ny endstops used to position specimens on the supports can be withdrawn immediately before a test to leave at least 13 mm clear space beyond both ends of the longest dimension of the test piece. f) If the machine is fitted with a U-type pendulum that leaves less than 13 mm clear space between the fr
41、ee ends of the specimen and the sides of the pendulum, check that protective shrouds are placed on the anvils to prevent the specimen contacting the pendulum after impact. These shrouds shall be approximately 1.5 mm thick, with a 1.5 mm radius on the underside, a clearance of less than 1.5 mm top an
42、d side to the pendulum overhang and a minimum hardness of 45 HRC. 8 Test procedure 8.1 Control of temperature 8.1.1 At all temperatures, the temperature of the test specimen shall be controlled to 18C. NOTE At any test temperature either cooling or heating may be required. 8.1.2 The cooling or heati
43、ng system shall be designed to ensure that all test pieces immersed in the cooling or heating medium attain the medium temperature throughout the whole of their section. In all cases the temperature of the test piece shall not deviate from the specified testing temperature by more than 18C. Ensure t
44、hat those portions of any appliance which come into contact with the test piece during transfer to the testing machine are at the same temperature as the test piece. Break the test piece within 5 s from the time of removal from the medium. 8.2 Test 8.2.1 Wipe the anvil clean and dry. 8.2.2 Set the p
45、endulum and energy indicator to the starting position. Place the test piece on the supports with the notched face in contact with both anvils and in such a position that the plane of symmetry of the notch is within 0.10 mm of the centre of the gap between the anvils. NOTE It is recommended that self
46、-centring tongs or spatulae be used to locate the test piece correctly in the machine. 8.2.3 Check that endstops are removed see 7.2e) or that shrouds are in place see 7.2f). 8.2.4 Release the pendulum without shock and note the absorbed energy reading immediately the indicator point comes to rest a
47、nd before relocating the pendulum for subsequent testing, in order to avoid spurious readings due to jarring of the indicator pointer. 8.2.5 On compensated machines record the indicated reading as the absorbed energy value. On non-compensated machines deduct the the slave pointer friction (A sp ) an
48、d windage losses (A fw ), as given on the calibration certificate, from each indicated test reading obtained, and record the corrected result as the absorbed energy value. 8.2.6 NOTE The test piece might be not completely broken by the impact and this could be significant. If the test piece has pass
49、ed through the anvils without separation, record this fact. If the test piece absorbs the full energy of the blow without passing through the anvils, the result is indeterminable. Record that the impact value for the specimen exceeds the maximum energy rating of the machine or the test range used. 8.2.7 Absorbed energy values above 80 % of the range in use shall be reported as approximate.6 BSI 1998 BS 131-6:1998 8.3 Lateral expansion After fracture the test piece is distorted. This distortion man
