1、INTERNATIONAL STANDARD INTERNATIONAL ORGANIZATION FOR STANDARDIZATION .MEXaYHAPOAHAR OPrAHM3AUMI( II0 CTAHIIAPTM3AUAIIORGANISATION INTERNATIONALE DE NORMALjSATlON Grey cast iron - Beam unnotched impact test Fonte grise - Essai de choc sur 4prouvette non enteifike First edition - 1975-11-01 UDC 669.1
2、31.6 : 620.178.742 Descriptors : cast iron, grey iron, tests, impact tests. Ref. No. IS0 946-1975 (E) Price based on 3 pages Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,
3、-,-FOREWORD IS0 (the International Organization for Standardization) is a worldwide federation of national standards institutes (IS0 Member Bodies). The work of developing International Standards is carried out through IS0 Technical Committees. Every Member Body interested in a subject for which a T
4、echnical Committee has been set up has the right to be represented on that Committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. Draft International Standards adopted by the Technical Committees are circulated to the Member Bodies
5、 for approval before their acceptance as International Standards by the IS0 Council. Prior to 1972, the results of the work of the Technical Committees were published as IS0 Recommendations; these documents are now in the process of being transformed into International Standards. As part of this pro
6、cess, Technical Committee ISO/TC 25 has reviewed IS0 Recommendation R 946 and found it technically suitable for transformation. International Standard IS0 946 therefore replaces IS0 Recommendation R 946-1969 to which it is technically identical. IS0 Recommendation R 946 was approved by the Member Bo
7、dies of the following countries : Belgium Brazil Canada Chile Egypt, Arab Rep. of Finland France Germany Greece India Ireland Israel Italy Korea, Rep. of Netherlands Norway Poland Portugal Romania South Africa, Rep. of Sweden Switzerland Thailand Turkey United Kingdom Yugoslavia The Member Body of t
8、he following country expressed disapproval of the Recommendation on technical grounds : Czechoslovakia The Member Bodies of the following countries disapproved the transformation of ISO/R 946 into an International Standard : Czechoslovakia Switzerland 0 lnternationale Organization for Standardizatio
9、n, 1975 l Printed in Switzerland Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-INTERNATIONAL STANDARD IS0 946-1675 (E) Grey cast iron - Beam unnotched impact test 1 SCO
10、PE AND FIELD OF APPLICATION This International Standard specifies requirements for the determination of the impact strength of grey cast iron containing graphite in flake form. 2 PRINCIPLE 2.1 The test consists in breaking, by a single blow from a swinging hammer, a series of unnotched machined cyli
11、ndrical test pieces resting freely between supports, and measuring the difference between the kinetic energy of the hammer immediately before fracture and its residual energy after the fracture of the test piece. 2.2 The impact strength of the grey cast iron is the apparent energy absorbed in fractu
12、re denoted by the symbol KG, and is expressed in joules (see also annex A). 3 SYMBOLS AND DESIGNATIONS 1 2 3 Initial potential energy of testing machine I 4 Distance between supports 5 Radius of curvature of supports 6 Taper of supports 7 Angle at tip of hammer 8 - Radius of curvature of hammer 9 V
13、10 I I Speed of hammer at instant of striking KG Apparent energy absorbed in fracture I I d EP L - Designation Length of test piece Diameter of test piece 1 I I 1 Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networkin
14、g permitted without license from IHS-,-,-IS0 946-1975 (El 4 MACHINED STANDARD TEST PIECES TABLE 2 - Characteristics of testing machine 4.1 The test bars shall be cast as cylindrical bars having a diameter of 3of2 Ornrn and a minimum length of 150 mm. 4.2 The machined standard test piece shall have t
15、he dimensions shown in table 1. The test piece shall be well machined with a good surface finish. TABLE 1 - Dimensions of test pieces 1 5 METHOD OF CASTING TEST BARS 5.1 The test bars shall be cast separately in sand moulds and the structure shall be entirely grey. 5.2 Each bar shall be separated fr
16、om its neighbour or any other casting in the same mould by not less than 50 mm. 5.3 The test bars shall be cast from the same metal as that used for the castings they represent. Precautions shall be taken to ensure sound test bars. 5.4 The test bars shall not be removed from the mould as long as the
17、 temperature is above 500 “C. 5.5 If any test piece shows defective machining or obvious lack of continuity in the metal, it shall be discarded and replaced by another test piece. 5.6 If the castings represented are heat-treated, the test bars shall be heat-treated at the same time and under the sam
18、e conditions as the castings. 6 TESTING MACHINE 6.1 The testing machine shall be constructed and installed steady and rigid. 6.2 The conditions shown in table 2 shall be satisfied. 6.3 The plane of swing of the hammer shall be vertical. The machine shall be constructed so that the loss of energy (su
19、ch as from translation, rotation or vibration) in the machine framework during a test is negligible. 6.4 The height of the centre of percussion above the point of impact of the hammer shall be 3 + 3 mm. 2 Designation Nominal values and tolerances Initial potential energy of testing machine, E, 50+2J
20、 Distance between supports, L 100 +“*5 mm 0 Radius of curvature of supports Taper of supports Angle at tip of hammer Radius of curvature of hammer Speed of hammer at instant of striking, v 1 to 1,5 mm 1:5 30+ 1” 2 to 2,5 mm 3,6 to 4.2 m/s 6.5 The accuracy of the graduation of the scale of the machin
21、e shall be f. 0,5 % of the maximum striking energy of the machine. 7 TEST REQUIREMENTS 7.1 The test piece shall lie squarely against the supports with the plane of symmetry of the hammer midway between them (see the figure). 7.2 The test shall be carried out at a temperature between 10 and 30 “C. 8
22、METHOD OF TESTING 8.1 An impact test shall consist of the fracture of at least four test pieces (see annex B). 8.2 After the four test pieces have been broken under the conditions described above, the arithmetical average Kof the values obtained and the difference AKG between the greatest and the le
23、ast shall be calculated. 8.3 If AKG is not more than 0,4 KG, the impact strength shall be expressed as KG. 8.4 If AKG is greater than 0,4 KG, the test shall be repeated with a fifth test piece which has been held in reserve. The arithmetical average KG of the values obtained and the difference A KG
24、between the greatest and the least shall be calculated. 8.5 If AKG is not more than 0,5 KG, the impact strength shall be expressed as KG. 8.6 If AKG is greater than 0,5 a, the test shall not be considered significant enough to give an acceptable estimate of KG. 8.7 The test shall also be discarded i
25、f obvious flaws on the surface or on the broken face of certain test pieces have made it impossible to obtain the required number of values. Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without li
26、cense from IHS-,-,-IS0 946-1975 (E) ANNEX A CALCULATION OF IMPACT MODULUS FOR NON-STANDARD TEST PIECES If it is found necessary to carry out the impact test on test pieces not of the standard size specified in clause 4, it may be KG useful to calculate the “impact modulus” MC, i.e. the ratio 7, wher
27、e KG is the apparent energy absorbed in fracture, expressed in this case in joules, and V is the volume of test piece between the supports, expressed in cubic centimetres. It has been found that, within acceptable practical limits, for the same grade of iron (same material), the impact modulus is in
28、dependent of the diameter of the machined test piece, if the following conditions are observed : a) the test pieces are of proportional dimensions, I = 6 d; b) the distance between supports is proportional to the dimensions of the test piece, L = 5 d; c) the value of F remains above 0,4; d) the diam
29、eter dais between 12 and 29 mm; e) all the other conditions of test and particularly the velocity of impact v and the diameter of the original bar or the mass of the test piece remain unchanged. In this case the impact modulus of the standard test piece (d = 20 mm) shall be calculated according to t
30、he formula MC Jkma = y& KG Jl ANNEX B NOTE ON COEFFICIENTS FOR CALCULATION OF IMPACT STRENGTH The terms of clause 8 were drawn up so that the coefficient of dispersion of the impact strength thus defined would be comparable with that for tensile strength determined on the rupture of a single test pi
31、ece, under the conditions of ISO/R 185, Classification of grey cast iron. The numerical coefficients introduced in the same clause were determined from the results of numerous tests carried out in various countries, using standard methods of statistical quality control. 3 Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
