Charpy impact test on metallic materials

Transcription

1 BRITISH STANDARD BS EN :1993 Charpy impact test on metallic materials Part 2: Method for the verification of impact testing machines The European Standard EN :1993 has the status of a British Standard UDC 669: :620.1

2 BSEN :1993 Cooperating organizations The European Committee for Standardization (CEN), under whose supervision this European Standard was prepared, comprises the national standards organizations of the following countries: Austria Belgium Denmark Finland France Germany Greece Iceland Ireland Italy Luxembourg Netherlands Norway Portugal Spain Sweden Switzerland United Kingdom Oesterreichisches Normungsinstitut Institut belge de normalisation Dansk Standardiseringsraad Suomen Standardisoimisliito, r.y. Association française de normalisation Deutsches Institut für Normung e.v. Hellenic Organization for Standardization Technological Institute of Iceland National Standards Authority of Ireland Ente Nazionale Italiano di Unificazione Inspection du Travail et des Mines Nederlands Normalisatie-instituut Norges Standardiseringsforbund Instituto Portuguès da Qualidade Asociación Española de Normalización y Certificación Standardiseringskommissionen i Sverige Association suisse de normalisation British Standards Institution This British Standard, having been prepared under the direction of the Iron and Steeland the Non-ferrous Metals Standards Policy Committees, was published under the authority of the Standards Board and comes into effect on 15 August 1993 BSI Amendments issued since publication Amd. No. Date Comments The following BSI references relate to the work on this standard: Committee reference ISM/NFM/4 Draft for comment 90/43831 DC ISBN

3 BSEN :1993 Contents Page Cooperating organizations Inside front cover National foreword ii Foreword 2 Text of EN National annex NA (informative) Committees responsible Inside back cover National annex NB (informative) Cross-references Inside back cover BSI i

4 BSEN :1993 National foreword This British Standard has been prepared under the direction of the Iron and Steel and the Non-ferrous Metals Standards Policy Committees and is the English language version of EN Metallic materials Charpy impact test Part 2: Verification of the testing machine (pendulum impact), drawn up by ECISS (European Committee for Iron and Steel Standardization) and published by the European Committee for Standardization (CEN). It incorporates the corrigendum dated It partially supersedes BS 131-4:1972. An amendment to BS131-4 will be published simultaneously with this standard. BS is to be used for the verification of Izod machines (which is not addressed in BS EN ). 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 This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages 2to 20, 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 cover. ii BSI

5 EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM EN November 1992 UDC 669: :620.1 Descriptors: Metal products, mechanical tests, bend tests, impact tests, Charpy impact tests, test equipment, verification, definitions English version Metallic materials Charpy impact test Part 2: Verification of the testing machine (pendulum impact) Matériaux métalliques Essai de flexion par choc sur éprouvette Charpy Partie 2: Vérification de la machine d essai (mouton-pendule) Metallische Werkstoffe Kerbschlagbiegeversuch nach Charpy Teil 2: Prüfung der Prüfmaschine (Pendelschlagwerk) This European Standard was approved by CEN on CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comité Européen de Normalisation Europäisches Komitee für Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1992 Copyright reserved to CEN members Ref. No. EN :1992 E

6 Foreword This European Standard has been prepared by ECISS/TC 1A, Mechanical and physical tests, the secretariat of which is held by AFNOR. At its meeting on 25 and 26 January 1990, the TC agreed to publish this text as pren (yellow proof). The following member bodies were represented at this meeting: Belgium, France, Germany, Italy, Luxembourg, Netherlands, Portugal, United Kingdom and also the BCR. At its meeting on 20th June 1991, the TC agreed to submit this document to COCOR for approval (white proof). The Coordinating Commission (COCOR) of ECISS agreed on /28 to submit this draft European Standard to the CEN formal vote. This document was approved by CEN and according to the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. Contents Page Foreword 2 Introduction 5 1 Scope 5 2 Normative references 5 3 Definitions Industrial pendulum impact testing machine Reference pendulum impact testing machine Anvils Supports Striker Centre of striker Centre of percussion Rated initial potential energy (rated energy) A N Effective initial potential energy (potential energy) A p Indicated absorbed energy (indicated energy) A s Effective energy absorbed (energy absorbed) A v Reference test piece Reference value Geometry of the test piece Base of the frame 7 4 Symbols and designations 7 5 Direct verification of the pendulum impact testing machine Machine framework Pendulum Framework/pendulum position Test piece supports and anvils Clearance between anvils and pendulum Position of centre of percussion Energy indicator Potential energy (A p ) Indicated energy error (A s ) Friction losses Impact velocity 12 6 Indirect verification of the pendulum impact testing machine Principle Charpy V reference test pieces Procedure 12 2 BSI

7 Page 6.4 Repeatability and error of the pendulum impact testing machine Evaluation of the verification 13 7 Verification report 14 8 Intervals between indirect verifications Direct verification Indirect verification 14 Annex A (informative) Direct method of verifying certain geometric properties using a jig 15 Annex B (informative) Guide to preparation and characteristics of the Charpy V reference test pieces 20 Figure 1 Test piece anvils and supports 6 Figure 2 Representation of the definitions of the pendulum geometry 8 Figure 3 Representation of the angles used for the calculation of the impact energy 8 Figure 4 Types of striker 10 Figure A.1 Jig 16 Figure A.2 Change of position from A to B corresponding to the striker travelling 30mm 17 Figure A.3 Example of application of the jig illustrated in Figure A.1 18 Figure A.4 Example of application of the jig illustrated in Figure A.1 19 Table 1 7 Table 2 Values of the geometric properties 13 Table 3 Repeatability and error values of the pendulum impact testing machine 13 Table B.1 Dimensions of the reference test pieces 20 Table B.2 Conditions of repeatability and error of the reference pendulum 20 Table B.3 Values of the standard deviation for the characterization of the reference test piece batch 20 BSI

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9 Introduction The European Standard EN concerns metallic materials Charpy impact test and comprises the following Parts. Part 1: Method of test; Part 2: Verification of pendulum impact testing machines. 1 Scope This European standard applies to the verification of (pendulum) impact testing machines used for the Charpy impact test as described in EN 10045/1. It describes 2 methods: the direct method allowing the physical and geometrical properties of the different parts of the testing machine to be verified statically and separately, the indirect method: global verification method of the pendulum impact testing machine using Charpy V reference test pieces as specified in6.2. The direct method shall be used, firstly, when the machine is being installed or repaired and, secondly, if the indirect method gives an incorrect result (see8.1), in order to find the reason for this. This standard is also applicable to reference pendulum impact testing machines, the geometrical characteristics of which are defined in Annex B. This standard is also applicable to pendulum impact machines of different capacities or different design. Pendulum impact testing machines verified in accordance with this standard and assessed as satisfactory are considered as valid to carry out impact testing with notches of different types. The apparatus used for the direct method shall have a certified traceability relative to the SI system of units. Annex A describes, for information purposes, a direct method of verifying certain geometrical properties using a jig. Annex B describes, for information purposes, a guide to the preparation of reference test pieces and their characteristics. 2 Normative references This European Standard incorporates by dated and undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 10045/1, Metallic materials Charpy impact test Part 1: Test method. 3 Definitions For the purposes of this European Standard, the following definitions shall apply: 3.1 industrial pendulum impact testing machine pendulum impact testing machine used for industrial or laboratory tests, on metallic materials; these machines shall not be used for determining reference values (see3.13) 3.2 reference pendulum impact testing machine pendulum impact testing machine used for determining reference values. The requirements for verification of this type of machine are stricter than those for industrial machines (seeb.3.1) 3.3 anvils part of the machine forming a vertical plane which holds the test piece when it is broken. The plane of the anvils is perpendicular to the plane of the supports (see Figure 1). 3.4 supports part of the machine forming a horizontal plane on which rests a test piece before it is broken by a hammer. The plane of the supports is perpendicular to the plane of the anvils (see Figure 1) 3.5 striker part of the hammer which is in contact with the test piece BSI

10 3.6 centre of striker the point on the striking edge of the pendulum which, when the pendulum is released, meets the horizontal plane over half the test piece 3.7 centre of percussion the point on a body where, on impact, the percussion action is the same as if the total mass of the body were concentrated at this point. When a pendulum hammer strikes a blow in a horizontal line passing through the centre of percussion, there shall be no resultant action on the axis of rotation (see Figure 2) 3.8 rated initial potential energy (rated energy) A N energy attributed by the designer of the pendulum hammer 3.9 effective initial potential energy (potential energy) A p the value determined by direct verification Figure 1 Test piece anvils and supports 3.10 indicated absorbed energy (indicated energy) A s the value of the energy indicated by the pointer or read from the indicator 3.11 effective energy absorbed (energy absorbed) A v the total energy required to break a test piece when it is tested on a pendulum impact testing machine. It is equal to the difference in potential energy between the initial position of the pendulum and the end of the first half-swing during which the test piece is broken 3.12 reference test piece impact test piece used to verify the compliance of a pendulum hammer by comparison of the energy absorbed by the machine with the reference value supplied with the test pieces 3.13 reference value value of the energy absorbed, supplied with the reference test pieces and determined by test on reference pendulum impact testing machines 6 BSI

11 3.14 geometry of the test piece the test piece being placed on the supports in the test position: height: distance between the notched face and the opposite face; width: dimension perpendicular to the height that is parallel to the notch; length: largest dimension at right angles to the notch. Table base of the frame Symbols a Unit Definitions A N A p A s A v F F 1 L l l 1 l 2 p p9 p t T T M T m µ E E BCR J J J J N N m m m m J J J s s s s o o J J a See Figure 2 and Figure 3. Rated initial potential energy (rated energy) Effective initial potential energy (potential energy) Indicated absorbed energy (indicated energy) Effective energy absorbed (energy absorbed) part of the machine framework located below the horizontal plane of the supports 4 Symbols and designations For the purposes of this European Standard, the symbols and definitions given in Table 1 are applicable: Force exerted by the pendulum on the force-proving device for distance l 2 Weight of pendulum Distance between the centre of the striker and the axis of rotation of the pendulum (length of the pendulum) Distance between the centre of gravity of the pendulum and the axis of rotation Distance between the centre of percussion and the axis of rotation Distance between the point of application of force F and the axis of rotation Friction losses due to the drag of the pointer Friction losses resulting from air resistance and beating friction Correction of the energy losses for a rise angle Period of swing of the pendulum Total duration of 100 swings of the pendulum Maximum value of T Minimum value of T Fall angle Rise angle Value of the energy absorbed from the batch of Charpy V reference test pieces Certified energy value from the batch of BCR test pieces BSI

12 Figure 2 Representation of the definitions of the pendulum geometry 5 Direct verification of the pendulum impact testing machine This verification relates to the following points: machine framework, pendulum, framework/pendulum position, test piece supports and anvils, position of centre of percussion, energy indicator, initial potential energy, indicated energy error, friction losses, impact velocity. 5.1 Machine framework The foundation of the pendulum impact testing machine cannot normally be verified once the machine has been installed. Consequently, the documentation prepared when the machine is installed shall prove that the mass of the foundation is at least 40times that of the pendulum which shall also be given in the documentation. NOTE For machines manufactured after the publication of this standard, it is recommended that the mass of the pedestal of the machine should be at least 12 times the mass of the pendulum. Verification of the pendulum impact testing machine shall comprise: a) verification that the tightening of the bolts complies with that specified by the manufacturer. This value shall be indicated on the documentation provided by the manufacturer; b) verification that the pendulum impact testing machine is not subject to any external vibration transmitted by the foundation. NOTE This may be done, for example, by placing a container of water on the machine framework and checking that there are no ripples on the surface of the water. Figure 3 Representation of the angles used for the calculation of the impact energy 8 BSI

13 5.2 Pendulum The width of the striker shall be between 10 and 18mm. The dimensions of the striker shall be verified using jigs. The angle of the tip of the striker shall be30 ± 1, and the radius of curvature of the striking edge shall be , 0 mm. The angle between the line of contact of the striker and horizontal axis of the test pieces shall be90 ± 2. NOTE One possible method of verification is as follows. Wrap a test piece 55 mm long and of cross-section mm tightly in a thin sheet of paper and place the test piece on the test piece holder. Also wrap the striking edge in carbon paper, the carbon side facing outwards. Move the pendulum a few degrees from its equilibrium position and drop it on the test piece, ensuring that it does not make a second contact with the test piece. The mark by the carbon paper on the paper the test piece is wrapped in makes it possible to measure its orientation in relation to the horizontal axis of the test piece. This test may be carried out jointly with verifying the contact of the test piece over its whole length (see 5.3). The mechanism for releasing the pendulum from its initial position shall be capable of operating freely and releasing the pendulum without any initial jerk, delay or transverse vibration. If this mechanism also includes a braking system, means shall be provided to prevent the brake being applied accidentally. 5.3 Framework/pendulum position The machines shall have a reference plane on the basis of which the measurements can be taken. The machine shall be installed so that the reference plane is horizontal to within 2/1000. The axis of rotation of the pendulum shall be parallel to the reference plane to within 2/1000. This shall be certified by the manufacturer of the machine. For machines without a reference plane, the axis of rotation shall be horizontal to within 4/ This shall be verified by direct measurement, unless a reference plane can be machined on the machine and then the above requirement shall be met. When free, the pendulum shall hang so that the striking edge is ± 0,5 mm from the point at which the edge touches the test piece. NOTE This may be verified by means of a bar approximately 55 mm long and of rectangular cross-section: height 9,5mm and width approximately 10 mm. The distance between the striking edge and the bar is measured. The pendulum shall swing in a plane perpendicular to the axis of rotation to within 3/1000. The striking edge shall be in contact with the test piece along the whole width of the test piece. NOTE One possible method of verification is that described in5.2 for verifying the angle between the striker contact and the horizontal axis of the test piece. The pendulum shall be positioned so that the centre of the striking edge coincides with the median plane, to within± 0,5 mm between the test piece anvils. The transverse play of the pendulum bearings, measured at the striker, shall not exceed 0,25 mm when a transverse force of approximately 4 % of the mass of the pendulum is applied to the centre of the striker. The radial play of the pendulum bearing shall not exceed 0,08 mm when a force of 150 N± 10 N is applied at a distance L perpendicular to the plane of swing of the pendulum. NOTE The radial play may be measured, for example, by placing a dial gauge on the framework in order to indicate the movement at the end of the shaft at the point closest to the bearings. 5.4 Test piece supports and anvils The supports shall lie in one and the same plane; the distance between the support planes shall never exceed 0,1 mm. The supports shall be such that the axis of the test piece is parallel to the axis of rotation of the pendulum to within 3/1000. The anvils shall lie in one and the same plane; the distance between the two planes shall never exceed 0,1 mm. The angle between this plane and the plane of the supports shall be 90 ± 0,10. The distance between the anvils shall + 020, be 40 mm. 0 The radius of curvature of the anvils shall be , mm. 0 The angle of taper of the anvils shall be 11 ± Clearance between anvils and pendulum Sufficient clearance shall be provided so as to ensure that the broken parts of the test piece are free to fall from the machine with a minimum of interference and without rebounding onto the hammer before the pendulum has completed its swing. No part of the pendulum which passes between the anvils shall be thicker than 18mm. Two types of hammer are generally used. The C-shaped and U-shaped hammer (see Figure 4). For the C-shaped hammers, the broken parts of the test piece will not rebound onto the hammer if the play at each end of the test piece exceeds 13 mm. For the U-shaped hammers, means shall be provided to prevent the broken parts of the test piece from rebounding onto the hammer. BSI

14 In many machines using this type of hammer, safety stops shall be provided and installed and meet the following requirements: a) shall be approximately 1,5 mm thick; b) shall have a minimum hardness of 45HRC; c) shall have a corner radius of a least 1,5 mm; d) shall be positioned so that the play between the safety stop and the hammer does not exceed 1,5mm. NOTE For machines in which the hammer opening permits a play of at least 13mm between the end of the test piece (placed ready for the test) and the safety stops, requirements a) and d) do not apply. 5.6 Position of centre of percussion The distance l 1 from the centre of percussion to the axis of rotation is equal to the length of the simple synchronous pendulum of the testing machine. Therefore, determine the time t of the pendulum and calculate l 1 using the formula: l gt 2 1 = ; 2 Where g = 9,81 m/s 2 and ; 2 =9,87 giving: l 1 = 0,2485t 2 t shall be determined to the nearest 0,1% l 1 shall be equal to 0,995L ± 0,5%L a a Certain old type pendulum testing machines do not satisfy the requirement l L # L although, up to now, they have been regarded as giving correct data; the use of these machines will be tolerated as long l L #1, L Figure 4 Types of striker, and all the other conditions imposed by direct verification are met; and they are subject to indirect verification (see clause 6), the results of which shall meet the requirements in6.5 For a pendulum having a periodic time of approximately two seconds, t may be determined with sufficient accuracy by ascertaining for the calculation of t the mean of determinations of the total duration T of 100 complete swings provided the pendulum has not swung through an angle of more than 5 from its rest position and the difference between the maximum duration T M and the minimum duration T m during 100 swings does not exceed 0,2s. 5.7 Energy indicator The machine is graduated either in angles of rise or in energy absorbed Analogue scale The width of the scale graduation marks shall be uniform and the width of the pointer shall be approximately equal to the width of one graduation mark. The pointer shall permit a reading free from parallax. The resolution r of the indicator is obtained from the ratio of the pointer thickness and the minimum distance between the centres of two adjacent graduation marks. The recommended ratios are either 1 :4 or 1 :5 or 1 :10. The distance between two adjacent marks shall be at least 2,5 mm in order to be able to estimate 1/10 of a scale division. A scale division shall be equal to 1/100 of the initial potential energy at most and shall permit the energy to be estimated by an increment of at least0,25% of the initial potential energy Digital scale The resolution of the scale is regarded as one increment of the number on the digital indicator provided that the indication does not fluctuate by more than one increment. When the readings fluctuate by more than one increment, the resolution is taken to be equal to half the range of the fluctuation. 10 BSI

15 The resolution shall be at least 1/400 of the initial potential energy. 5.8 Potential energy (Ap) The potential energy shall be verified according to the following procedure and shall not differ from the nominal value (A N ) by more than ± 1,0 % General By the nature of its design, the centre of gravity of the pendulum is always very close to the striking edge of the pendulum and the straight line which prolongs this edge passes very close to the axis of rotation. Instead of determining the weight F 1 of the pendulum and the distance from its centre of gravity to the axis, it is easier to determine a force F such that acting at a known distance l 2 from the axis it has the same moment relative to this axis as the weight of the pendulum. NOTE l 2 may be equal to l Procedure Lift the pendulum so that its centre of gravity is in the horizontal plane of the axis of rotation to within 15/1000 (i.e. practically that the striking edge is in the horizontal plane of the axis) and support one point of this striker a distance l 2 from the axis on another horizontal striker perpendicular to the first one and supported by a balance beam or, better, by a dynamometer. Measure the force F exerted by the pendulum on the load measuring device and the distance l 2 from the anvil to the axis to the nearest0,2% (see Figure 2). The moment M of the pendulum is: M = Fl 2 Then measure the angle of rotation described by the pendulum to pass from the rest position to the fall position. This measurement shall be made using a cathetometer or an angle to an accuracy ± 0,065 (see Figure 3). The angle a may be greater than 90. A p = M(1 cos µ) = Fl 2 (1 cos µ) 5.9 Indicated energy error (A s ) The indicated energy error shall be determined as follows: For a machine of A joules, verify the indicator graduations corresponding to or 60-80percent of the initial potential energy A N. To do this, lift the pendulum driving the indicator in the rise direction until the indicator is on the graduation to be verified. Measure the angle of rise to within ± 0,065 (seefigure 3). The energy absorbed is equal to: A v = M(cos cos µ) The difference between the energy indicated A s and the absorbed energy A v, calculated on the basis of the measured values, shall not exceed 1% of the absorbed energy A v or ± 0,5 % of the potential energy A p. In each case, the greater value is permitted. This means that: (from 80% to 50 % of the rated energy A N ) (below 50% of the rated energy A N ) The precision required for measuring F, l 2, µ,, involves for A v a total mean error of approximately± 0,3% of the maximum indication of the machine scales. NOTE A s A v # ( 10, ) A v A s A v # ( 05, ) A p It should be remembered that the accuracy of the absorbed energy reading varies inversely to A v and this is important when A v is small in comparison with A p. Indicated energy values greater than 80 % of the initial potential energy are inaccurate and shall be recorded as being approximate. NOTE This requirement is to ensure that all the tests are carried out at deformation rates not varying by more than a factor of 2. The deformation rate is a function of the pendulum impact speed; for a pendulum impact testing machine, the speed decreases as the fracture progresses. The change in the pendulum speed may be calculated by determining, firstly, the impact speed (see 5.11) and the speed after impact using the same formula but replacing cos µ with cos (see Figure 3) Friction losses The breaking of the test piece involves energy absorption equal to the difference between the potential energy and the residual energy indicated by the rise of the pendulum taking into account just the energy losses that can actually be evaluated (see6.1) i.e.: the friction losses due to the drag of the pointer, the losses resulting from air resistance and beating friction. These losses are evaluated as follows Losses due to the drag of the pointer Move the pointer to a position corresponding to a rise angle of zero, let the pendulum fall normally (fall angle µ) but without the test piece in position and read off the rise angle 1, or the energy E 1 directly. BSI

16 Then, without resetting the pointer, let the pendulum fall a second time from the position corresponding to the fall angle and read off the new rise angle 2, or the energy E 2 directly. The friction losses of the pointer are equal to: p = M(cos 1 cos 2 ) when the scale is graduated in degrees or P = E 1 E 2 when the scale is graduated in energy units. In this calculation, use the mean values of 1 and 2 (or E 1 E 2 ) from four determinations Friction losses in the bearings and as a result of air resistance They are calculated as follows for a half-swing. After determining 2 or the energy E 2 (see5.10.1), return the pendulum to its initial position. Then, without re-adjusting the pointer, release the pendulum to allow 10 half-swings. After the pendulum has started its 11th half-swing, move the pointer about 5 % from its maximum reach and note the value of 3. Friction losses in the bearings and as a result of air-resistance for a half-swing are: p9 = 1/10M(cos 3 cos 2 ) if the scale is graduated in degrees or p9 = 1/10(E 3 E 2 ) if the scale is graduated in energy units The total losses p + p measured in this way shall not exceed 0,5% of the rated energy A N. NOTE The correction of losses corresponding to a rise angle may be calculated by assuming the proportionality of the losses to the angles passed through, i.e.: p b = p b + b p a + b 1 a + b 2 This approximate value approaches the actual correction value more closely as this absorbed energy decreases Impact velocity The impact velocity is equal to: v = v g is the velocity in metres per second is the acceleration of free fall (taken as g =9,81 m/s 2 ), µ is the fall angle (see Figure 3), L 2gL( 1 cos a) is the distance between the centre of the striker and the axis of rotation (in metres). This velocity shall be between 5,0 and 5,5 m/s. However, for machines manufactured before 1983, values between 4,5 and 7,0 m/s are permitted and shall be noted in the verification report. 6 Indirect verification of the pendulum impact testing machine 6.1 Principle Determination of the energy absorbed by breaking of the Charpy V reference test piece from batches whose breaking energy is known (seeannex B). This European Standard takes into account the total energy absorbed by the fracture of the test piece. The total absorbed energy consists of: a) the energy required to break the test piece; b) the internal energy losses of the pendulum impact testing machine in making the first half-swing from its initial position. The energy losses are due to: a) air resistance and bearing friction and friction due to drag of the pointer. These losses can be determined by the direction method (see5.10); b) foundation impacts and vibration of the framework and pendulum for which no suitable measurement methods or apparatus have been developed. NOTE For the evaluation the following energies are not taken in account: a) energy absorbed by the work of deformation at the anvils and at the centre of the striker. b) energy absorbed by friction of the test piece on the supporting surfaces and particularly the anvils. 6.2 Charpy V reference test pieces The Charpy V reference test pieces to be used for indirect verification of the pendulum impact testing machine are the national test pieces traceable to the BCR test pieces (seeannex B). The reference test pieces shall be used in accordance with the instructions given by the supplier. 6.3 Procedure Before carrying out the indirect verification, it is necessary to: check that the anvils are in good condition as described in5.4; check that the test piece is correctly centred and that the striker is in good condition; determine the friction losses as described in5.10. Indirect verification shall be carried out for a least two levels of energy within the range of application of the testing machine and for which Charpy V reference test pieces exist. These 2 levels shall be as close as possible to the extremities of this range. If more than 2 energy levels are verified, the additional levels shall be uniformly distributed in the range of application and as a function of the available reference test pieces. 12 BSI

17 Five test pieces are broken for each level, the test being carried out with test pieces at a temperature of 20 C± 2 C, each test piece being positioned with the tolerance indicated in Table 2. Any defects determined shall be indicated in the verification report. 6.4 Repeatability and error of the pendulum impact testing machine Let E 1, E 2... E 5 be the values of the energy absorbed when breaking 5 test pieces, classified in ascending order Repeatability The repeatability of the test machine under the specific verification conditions is characterized by the value E 5 E 1, i.e. E max E min. Table 2 Values of the geometric properties Parameters Unit Value Pendulum (5.2): angle of striker tip 30± 1 radius of striking edge mm Framework/pendulum position (5.3): horizontality of the axis of rotation of the pendulum machine with reference plane ± 2/1 000 relative to the reference plane machine without reference plane ± 4/1 000 parallelism between the axis of the test piece and the axis of rotation of the pendulum ± 3/1 000 distance between the striking edge and the centre of striker mm ± 0,5 position of striking edge relative to the plane of symmetry of the anvils mm ± 0,5 transverse play of bearings mm 0,25 radial play of bearings mm 0,08 Anvils (5.4): Radius of curvature of anvils mm Angle of taper of the anvils 11± 1 Angle between supports and anvils 90± 0,10 Distance between anvil planes mm 0,1 Distance between support planes mm 0,1 Distance between anvils mm Impact velocity (5.11): Impact velocity m/s 5 to 5, Error , 1 + 0, , 020 The error of the test machine under the specific verification conditions is characterized by the value E E where E E 1 E 2 E 3 E 4 E = E is the value of the absorbed energy of the batch of Charpy V reference test pieces. 6.5 Evaluation of the verification The verified test machine is only regarded as being satisfactory if the repeatability and error values are less than or equal to those in Table 3. Table 3 Repeatability and error values of the pendulum impact testing machine Energy level (J) Repeatability (J) <40 # 6 <4 Error (J) $ 40 # 15% of E <10% of E BSI

18 If the machine does not satisfy the repeatability and error values, it is advisable to look for the cause of this by applying the direct verification method (see clause5). 7 Verification report The verification report shall contain at least the following information: reference to this standard, identification of the test machine (type, mark, year of construction, series number), location of the machine, method of verification (direct or indirect), reference and value of the energy absorbed when breaking the reference test pieces used during indirect verification, any defects observed, the results of the verification, date of the verification, name or mark of the department carrying out the verification. 8 Intervals between indirect verifications 8.1 Direct verification Verification shall be carried out: when the pendulum impact testing machine is installed or dismantled or moved, if indirect verification produces results that do not comply. A simplified direct verification, concerning the geometric characteristics of the pendulum impact testing machine, shall be carried out before every indirect verification (see6.3). 8.2 Indirect verification The period between 2 indirect verifications depends on the maintenance standard and number of times the machine is used. Under normal conditions, it is recommended that indirect verification be carried out at intervals not exceeding 12 months. The pendulum impact testing machine shall in all cases be verified following installation and after it has undergone any major dismantling, moving, repair or adjustment operations. 14 BSI

19 Annex A (informative) Direct method of verifying the geometric properties of the pendulum impact testing machine using a jig A.1 Field of application This annex describes the direct method for verifying the geometric properties of pendulum impact testing machines using a jig. The properties which can be verified are: position of the striker in the plane of symmetry of the anvils; horizontalness of the axis of rotation of the pendulum; perpendicularity between the arm of the pendulum and the axis of rotation; alignment of the striker and the arm of the pendulum; perpendicularity between the plane of the striker and the test piece. This method may be applied to all machines and, in particular, to machines without a reference plane on the framework. A.2 Jig The shape and the dimensions of the jig are specified in Figure A.1. The jig has 2 ends (A and B) corresponding to 2 positions of use (A and B). A.3 Procedure Before using the jig, the following 2 properties shall be verified using a level: the horizontalness of the plane of the supports; the perpendicularity between the plane of the anvils and the plane of the supports. The jig shall be used in the 2 positions A and B. As shown in Figure A.2, passing from position A to position B corresponds to the striker travelling 30mm. Figure A.3 and Figure A.4 illustrate the way in which to use the jig for verifying the properties defined ina.1. BSI

20 Figure A.1 Jig 16 BSI

21 Figure A.2 Change of position from A to B corresponding to the striker travelling 30mm BSI

22 Figure A.3 Example of application of the jig illustrated in Figure A.1 18 BSI

23 Figure A.4 Example of application of the jig illustrated in Figure A.1 BSI

24 Annex B (informative) Guide to the preparation and characterization of Charpy V reference test pieces B.1 Scope The aim of this guide is to define the preparation and characterization of Charpy V reference test pieces. B.2 Preparation of reference test pieces All the test pieces in a single batch shall come from the same ingot or the same casting and shall have undergone the same heat treatment. Throughout all the stages of the preparation of the test pieces, special precautions shall be taken to ensure the best possible homogeneity of the test pieces. The test pieces shall be in steel or other metallic materials and shall be treated in such a way as to be able to obtain the following energy levels: low energy: medium energy: high energy: very high energy: The dimensional characteristics are those given in the Table B.1 below. Table B.1 Dimensions of the reference testpieces Length Height Width < 30 joules 30 to 110 joules 110 to 220 joules > 220 joules Notch angle 45 ± 1 Height remaining at notch root Radius at notch root Distance between the plane of symmetry of the notch and one of the ends of the test piece , Angle between the plane of symmetry of the notch and the longitudinal axis of the test piece 90 ± 2 10mm± 0,06 mm 10mm± 0,075mm 8mm± 0,06 mm 0,25 mm± 0,025 mm 27,5 mm± 0,10mm Angle between adjacent faces 90 ± 0,10 B.3 Characterization of Charpy reference test pieces This shall be carried out using a reference pendulum impact testing machine. B.3.1 Reference pendulum impact testing machine This pendulum impact testing shall only be used for characterizing reference test pieces. It shall meet the requirements of Table 2 in this standard except for the following parameters, for which stricter criteria shall be met: Radius of curvature of the anvils: mm Angle between supports and anvils: 90 ± 0,10 Distance between anvils: mm Position of the striking edge in relation to the plane of symmetry of the anvils: 0,25 mm The pendulum impact testing machine shall be verified using certified BCR 1) test pieces as described in this standard. In order to be considered as a reference pendulum impact testing machine, the impact testing machine shall meet the conditions of repeatability and error given in the following Table B.2. Table B.2 Conditions of repeatability anderror of the reference pendulum Energy level (J) Repeatability (J) Error (J) <40 # 3 <2 $ 40 # 7,5 % of E <5% of E B.3.2 Characterization of batches of reference test pieces Each batch will be characterized at the same temperature by breaking a given number of test pieces on a reference pendulum impact testing device. The number of test pieces for characterization of a batch is 25 irrespective of the number of test pieces in the batch. The energy value of the batch is the average of the energy values characterizing the batch. The standard deviation shall be calculated and shall meet the conditions defined in the following Table B.3. Table B.3 Values of the standard deviation for the characterization of the reference test piece Energy level (J) , , 0 <40 # 2,0 $ 40 # 5% of E Standard deviation (J) 1) Community Bureau of Reference (Bureau Communautaire de Reference). 20 BSI

25 BSEN :1993 National annex NA (informative) Committees responsible The United Kingdom participation in the preparation of this European Standard was entrusted by the Iron and Steel Standards Policy Committee (ISM/-) and the Non-ferrous Metals Standards Policy Committee (NFM/-) to Technical Committee ISM/NFM/4 upon which the following bodies were represented: Aluminium Federation British Gas plc British Non-ferrous Metals Federation British Railways Board British Steel Industry Copper Development Association Department of Trade and Industry (National Physical Laboratory) Department of Trade and Industry (National Measurement Accreditation Service) ERA Technology Ltd. GAMBICA (BEAMA Ltd.) Institute of Materials Ministry of Defence Society of British Aerospace Companies Limited University College London Welding Institute The following bodies were also represented in the drafting of the standard, through subcommittees and panels: AEA Technology BEAMA Ltd. Electricity Association Lloyd s Register of Shipping Steel Casting Research and Trade Association National annex NB (informative) Cross-references Publication referred to EN :1990 Corresponding British Standard BS EN :1990 Charpy impact test on metallic materials Part 1: Test method (V- and U-notches) BSI

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