इंटरनेट मानक Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. “जान1 का अ+धकार, जी1 का अ+धकार” “प0रा1 को छोड न’ 5 तरफ” Mazdoor Kisan Shakti Sangathan Jawaharlal Nehru “The Right to Information, The Right to Live” “Step Out From the Old to the New” IS 1586-2 (2012): Metallic Materials - Rockwell Hardness Test, Part 2: Verification and Calibration of Testing Machines ( Scales A,B,C,D,E,F,G,H, K, N,T) [MTD 3: Mechanical Testing of Metals] “!ान $ एक न’ भारत का +नम-ण” Satyanarayan Gangaram Pitroda ““IInnvveenntt aa NNeeww IInnddiiaa UUssiinngg KKnnoowwlleeddggee”” “!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता हहहहै””ै” Bhartṛhari—Nītiśatakam “Knowledge is such a treasure which cannot be stolen” IS 1586 (Part 2) : 2012 ISO 6508-2 : 2005 Hkkjrh; ekud èkkfRod lkefxz;k¡ jkWdosy dBksjrk ijh{k.k — Hkkx 2 ijh{k.k e'khuksa dk lR;kiu ,oa v'ka'kksèku LosQy ( A, B, C, D, E, F, G, H, K, N, T ) (pkSFkk iqujh{k.k) Indian Standard METALLIC MATERIALS — ROCKWELL HARDNESS TEST PART 2 VERIFICATION AND CALIBRATION OF TESTING MACHINES (SCALES A, B, C, D, E, F, G, H, K, N, T) ( Fourth Revision ) ICS 77.040.10 © BIS 2012 B U R E A U O F I N D I A N S T A N D A R D S MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002 August 2012 Price Group 8 Mechanical Testing of Metals Sectional Committee, MTD 3 NATIONAL FOREWORD This Indian Standard (Part 2) (Fourth Revision) which is identical with ISO 6508-2 : 2005 ‘Metallic materials — Rockwell hardness test — Part 2: Verification and calibration of testing machines (scales A, B, C, D, E, F, G, H, K, N, T)’ issued by the International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards on the recommendation of the Mechanical Testing of Metals Sectional Committee and approval of the Metallurgical Engineering Division Council. This standard was originally published in 1960 and subsequently revised in 1968, 1988 and 2000. This revision has been undertaken to harmonize it with the latest developments that have taken place at international level. The committee has now decided to adopt this standard under dual numbering system and make it align with ISO 6508 which is published in three parts, Similarly this standard is also published in three parts. The other parts in this series are: Part 1 Test method (scales A, B, C, D, E, F, G, H, K, N, T) Part 3 Calibration of reference blocks (scales A, B, C, D, E, F, G, H, K, N, T) The text of ISO Standard has been approved as suitable for publication as an Indian Standard without deviations. Certain terminology and conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following: a) Wherever the words ‘International Standard’ appear, referring to this standard, they should be read as ‘Indian Standard’. b) Comma (,) has been used as a decimal marker while in Indian Standards, the current practice is to use a point (.) as the decimal marker. The ambient temperature of 10° to 35°C as specified in this ISO Standard is not suitable for tropical countries like India where the atmospheric temperature is normally much higher than 35°C (the atmospheric temperature rises even up to 50°C) specially during summer. It is almost impossible to maintain this temperature, therefore, the requirement of ambient temperature, that is, 10° to 35°C is being modified. The prevailing atmospheric temperature for the tropical countries like India shall be referred. In this adopted standard, reference appears to certain International Standards for which Indian Standards also exist. The corresponding Indian Standards which are to be substituted in their respective places are listed below along with their degree of equivalence for the editions indicated: International Standard Corresponding Indian Standard Degree of Equivalence ISO 376 : 2004 Metallic materials — IS 4169 : 1988 Method for calibration Technically Equivalent Calibration of force-proving of force-proving instruments used for instruments used for verification of the verification of uniaxial testing uniaxial testing machines machines (first revision) ISO 6507-1 : 1997 Metallic materials IS 1501 : 2005 Method for Vickers Identical — Vickers hardness test — Part 1: hardness test for metallic materials Test method (third revision) ISO 6508-1 : 2005 Metallic materials IS 1586 (Part 1) : 2012 Metallic do — Rockwell hardness test — Part1: materials — Rockwell hardness test: Test method (scales A, B, C, D, E, Part 1 Test method (scales A, B, C, F, G, H, K, N, T) D, E, F, G, H, K, N, T) (fourth revision) (Continued on third cover) IS 1586 (Part 2) : 2012 ISO 6508-2 : 2005 Indian Standard METALLIC MATERIALS — ROCKWELL HARDNESS TEST PART 2 VERIFICATION AND CALIBRATION OF TESTING MACHINES (SCALES A, B, C, D, E, F, G, H, K, N, T) ( Fourth Revision ) 1 Scope This part of ISO 6508 specifies a method of verification of testing machines for determining Rockwell hardness (scales A, B, C, D, E, F, G, H, K, N, T) in accordance with ISO 6508-1. It specifies a direct method for checking the main functions of the machine operation and an indirect method suitable for the overall checking of the machine. The indirect method may be used on its own for periodic routine checking of the machine in service. If a testing machine is also to be used for other methods of hardness testing, it shall be verified independently for each method. This part of ISO 6508 is applicable to portable hardness testing machines. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 376:2004, Metallic materials — Calibration of force-proving instruments used for verification of uniaxial testing machines ISO 6507-1, Metallic materials — Vickers hardness test — Part 1: Test method ISO 6508-1, Metallic materials — Rockwell hardness test — Part 1: Test method (scales A, B, C, D, E, F, G, H, K, N, T) ISO 6508-3:2005, Metallic materials — Rockwell hardness test — Part 3: Calibration of reference blocks (scales A, B, C, D, E, F, G, H, K, N, T) 3 General conditions Before a Rockwell hardness testing machine is verified, the machine shall be checked to ensure that it is properly set up in accordance with the manufacturer's instructions: Especially it should be checked that: a) the plunger holding the indenter is capable of sliding in its guide; 1 IS 1586 (Part 2) : 2012 ISO 6508-2 : 2005 b) the indenter-holder is firmly mounted in the plunger; c) the test force can be applied and removed without shock or vibration and in such a manner that the readings are not influenced. It shall be checked that the readings are not affected either by movements of the test piece or by deformation of the frame. When a device is supplied, which locks the test piece against the upper part of the frame, the locking force shall exceed the total test force. The influence of deformations may be checked by using a plunger with a spherical tip (diameter of at least 10 mm), instead of the indenter, bearing against the anvil through a spacer and using the locking device when it is supplied. The material of the plunger and of the spacer have a hardness of at least 60 HRC. The readings of the measuring system (with preliminary force applied) before application and after removal of the additional force shall not differ by more than 1,5 Rockwell units (without locking equipment) and 0,5 Rockwell units (with locking equipment). 4 Direct verification 4.1 General 4.1.1 Direct verification should be carried out at a temperature of (23 ± 5) °C. If the verification is made outside of this temperature range, this shall be reported in the verification report. 4.1.2 The instruments used for verification and calibration shall be traceable to national standards. 4.1.3 Direct verification involves: a) calibration of the test force; b) verification of the indenter; c) calibration of the depth-measuring system; d) verification of the testing cycle. 4.2 Calibration of the test force 4.2.1 The preliminary test force F (see 4.2.4) and each total test force F used (see 4.2.5) shall be 0 measured, and, whenever applicable, this shall be done at not less than three positions of the plunger spaced throughout its range of movement during testing. The preliminary test force shall be held for at least 2 s. 4.2.2 Three readings shall be taken for each force at each position of the plunger. Immediately before each reading is taken, the plunger shall be moved in the same direction as during testing. 4.2.3 The forces shall be measured by one of the following two methods: ⎯ by means of a force proving device in accordance with ISO 376:2004, class 1, or ⎯ by balancing against a force, accurate to ± 0,2 %, applied by means of calibrated masses or by another method having the same accuracy. 4.2.4 The tolerance on the preliminary test force F (before application and after removal of the additional 0 test force F ) shall be ± 2,0 %. 1 4.2.5 The tolerance on the total test force F shall be ± 1,0 %. Each individual value of F shall be within this tolerance. 2 IS 1586 (Part 2) : 2012 ISO 6508-2 : 2005 4.3 Verification of the indenter 4.3.1 Diamond cone indenter (scales A, C, D, N) To verify the reliable performance of the conical indenter in conformance with this part of ISO 6508, a direct and an indirect verification shall be carried out. 4.3.1.1 Direct verification 4.3.1.1.1 The surfaces of the diamond cone and spherical tip shall be polished for a penetration depth of 0,3 mm and shall blend in a truly tangential manner. Both surfaces shall be free from surface defects. 4.3.1.1.2 The verification of the shape of the indenter can be made by direct measurement or by measurement of its projection on a screen. The verification shall be made at not less than four equally spaced sections. 4.3.1.1.3 The diamond cone shall have an included angle of (120 ± 0,35)°. Deviations from straightness of the generatrix of the diamond cone, adjacent to the blend, shall not exceed 0,002 mm over a minimum length of 0,4 mm. 4.3.1.1.4 The angle between the axis of the diamond cone and the axis of the indenter-holder (normal to the seating surface) shall not exceed 0,5°. 4.3.1.1.5 The tip of the indenter shall be spherical. Its radius shall be determined from single values, measured in the axial section planes defined in 4.3.1.1.2. The distance between the concentric circles shall be no more than 0,004 mm. Each single value shall be within (0,2 ± 0,015) mm. The mean value out of at least four single values shall be within (0,2 ± 0,01) mm. NOTE 1 The radius can be obtained by determining the intersection of two segments of the concentric circles. NOTE 2 The single value is the mean value of the two radii of the concentric circles. Measurement with a collimator device is also available. In this case, the measurements should be carried out at least in four central angles and the central angle of 120° must be included. 4.3.1.2 Indirect verification The hardness values given by the testing machine depend not only on the dimensions given in 4.3.1.1.3 and 4.3.1.1.5, but also on the surface roughness and the position of the crystallographic axes of the diamond, and the seating of the diamond in its holder. To examine this influence, the indirect verification of the indenter shall be performed on four reference blocks which shall be calibrated for the hardness levels given in Table 1 or on blocks giving equivalent total depths of indentation. Table 1 — Hardness levels for different scales Scale Hardness Ranges HRC 23 20 to 26 HRC 55 52 to 58 HR45N 43 40 to 46 HR15N 91 88 to 94 3 IS 1586 (Part 2) : 2012 ISO 6508-2 : 2005 For each block, the mean hardness value of three indentations made using the indenter to be verified shall not differ from the mean hardness value of the three indentations obtained with the indenter, calibrated in accordance with 4.5 of ISO 6508-3:2005 by more than ± 0,8 Rockwell units. The indentations made with the indenter to be verified and with the above-mentioned indenter should be adjacent. NOTE This can be performed with a calibration machine in accordance with the procedure described in Clause 5 of ISO 6508-3:2005. The hardness testing machines used for this indirect verification shall comply with the following tolerances for the test forces: F : ± 1,0 % 0 F : ± 0,5 % The test shall be carried out in accordance with ISO 6508-1. 4.3.2 Ball indenter (scales B, E, F, G, H, K, T) 4.3.2.1 For the purpose of verifying the size and the hardness of the balls, one sample selected at random from a batch shall be tested. The balls verified for hardness shall be discarded. 4.3.2.2 The balls shall be polished and free from surface defects. 4.3.2.3 The user shall either measure the balls to ensure that they meet the following requirements, or shall obtain balls from a supplier certifying that the following conditions are met. 4.3.2.3.1 The diameter, measured at no less than three positions, shall not differ from the nominal diameter by more than the tolerance given in Table 2. Table 2 — Tolerances for the different ball diameters Ball diameter Tolerance Rockwell hardness scale mm mm B 1,587 5 ± 0,003 5 F 1,587 5 ± 0,003 5 G 1,587 5 ± 0,003 5 T 1,587 5 ± 0,003 5 E 3,175 ± 0,004 H 3,175 ± 0,004 K 3,175 ± 0,004 4.3.2.3.2 The characteristics of the hardmetal balls shall be as follows: ⎯ hardness: the hardness shall be no less than 1 500 HV, when determined using a test force of at least 4,903 N in accordance with ISO 6507-1. The hardmetal ball may be tested directly on this spherical surface or by sectioning the ball and testing on the ball interior. An example for HV 10 is given in Table 3. ⎯ density: ρ = (14,8 ± 0,2) g/cm3. NOTE The following chemical composition is recommended: — tungsten carbide (WC) balance — total other carbides 2,0 % — cobalt (Co) 5,0 % to 7,0 % 4 IS 1586 (Part 2) : 2012 ISO 6508-2 : 2005 4.3.2.3.3 The hardness of steel balls shall be no less than 750 HV, when determined using a test force of 98,07 N in accordance with ISO 6507-1 (see Table 3). Table 3 — Values of the mean diagonal (HV10) for the determination of the hardness of the ball indenters Ball diameter Maximum value of the mean diagonal made on the spherical surface of the ball with a Vickers indenter at 98,07 N (HV10) mm mm Steel ball Hardmetal ball 3,175 0,153 0,109 1,587 5 0,150 0,107 4.4 Calibration of the depth-measuring system 4.4.1 The depth-measuring system shall be calibrated over no less than three intervals, including the intervals corresponding to the lowest and highest hardness for which the scales are normally used, by making known incremental movements of the indenter in the direction of increasing hardness values. 4.4.2 The instrument used to verify the depth-measuring system shall have an accuracy of 0,000 2 mm. The depth-measuring system shall correctly indicate within ± 0,001 mm for the scales A to K and within ± 0,000 5 mm for scales N and T, i. e. within ± 0,5 of a scale unit, over each range. NOTE If it is not possible to verify the depth-measuring system directly, its performance can be derived from the results of an indirect verification, using reference blocks and a certified indenter, and making corrections for known errors (see 5.2). 4.5 Verification of the testing cycle The testing cycle shall conform to the testing cycle given in ISO 6508-1 and shall be timed with an uncertainty less than ± 0,5 s. 5 Indirect verification 5.1 General Indirect verification should be carried out at a temperature of (23 ± 5) °C by means of reference blocks calibrated in accordance with ISO 6508-3. If the verification is made outside of this temperature range, this shall be reported in the verification report. 5.2 Procedure 5.2.1 For the indirect verification of a testing machine, the following procedures shall be applied. The testing machine shall be verified for each scale for which it shall be used. For each scale to be verified, reference blocks from each of the hardness ranges given in Table 4 shall be used. The hardness values of the blocks shall be chosen to approximate the limits of the intended use. 5.2.2 On each reference block, five indentations shall be uniformly distributed over the test surface and each hardness number observed to within 0,2 of a scale unit. Before making these indentations, at least two preliminary indentations shall be made to ensure that the machine is working freely and that the reference block, the indenter and the anvil are seating correctly. The results of these preliminary indentations shall be ignored. The test shall be made in accordance with ISO 6508-1. 5