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Designation: E 10 – 07a American Association State Highwayand Transportation Officials Standard AASHTO No.: T70–86 Standard Test Method for Brinell Hardness of Metallic Materials1 This standard is issued under the fixed designation E 10; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense. 1. Scope 1.1 This test method covers the determination of the Brinell hardness of metallic materials by the Brinell indentation hardness principle. This standard provides the requirements for a Brinell testing machine and the procedures for performing Brinell hardness tests. 1.2 This standard includes additional requirements in four annexes: Verification of Brinell Hardness Testing Machines Annex A1 Brinell Hardness Standardizing Machines Annex A2 Standardization of Brinell Hardness Indenters Annex A3 Standardization of Brinell Hardness Test Blocks Annex A4 1.3 This standard includes nonmandatory information in an appendix which relates to the Brinell hardness test: Table of Brinell Hardness Numbers Appendix X1 Examples of Procedures for Determining Brinell Hardness Uncertainty Appendix X2 1.4 At the time the Brinell hardness test was developed, the force levels were specified in units of kilograms-force (kgf). Although this standard specifies the unit of force in the International System of Units (SI) as the Newton (N), because of the historical precedent and continued common usage of kgf units, force values in kgf units are provided for information and much of the discussion in this standard refers to forces in kgf units. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety and health practices and determine the applica- bility of regulatory limitations prior to use. 2. Referenced Documents 2.1 ASTM Standards: 2 E 29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications E 74 Practice of Calibration of Force-Measuring Instru- ments for Verifying the Force Indication of Testing Ma- chines E 140 Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, and Scleroscope Hardness E 384 Test Method for Microindentation Hardness of Ma- terials 2.2 American Bearings Manufacturer Association Stan- dard: ABMA 10-1989 Metal Balls3 2.3 ISO Standards: ISO/IEC 17011 Conformity Assessment—General Require- ments for Accreditation Bodies Accrediting Conformity Assessment Bodies4 ISO/IEC 17025 General Requirements for the Competence of Calibration and Testing4 3. Terminology and Equations 3.1 Definitions: 3.1.1 calibration—determination of the values of the sig- nificant parameters by comparison with values indicated by a reference instrument or by a set of reference standards. 3.1.2 verification—checking or testing to assure conform- ance with the specification. 3.1.3 standardization—to bring in conformance with a known standard through verification or calibration. 3.1.4 Brinell hardness test—an indentation hardness test using a verified machine to force an indenter (tungsten carbide ball with diameter D), under specified conditions, into the surface of the material under test. The diameter of the resulting indentation d is measured after removal of the force. 3.1.5 Brinell hardness number—a number, which is propor- tional to the quotient obtained by dividing the test force by the curved surface area of the indentation which is assumed to be spherical and of the diameter of the ball. 1 This test method is under the jurisdiction of ASTM Committee E28 on Mechanical Testing and is the direct responsibility of Subcommittee E28.06 on Indentation Hardness Testing. Current edition approved April 1, 2007. Published June 2007. Originally approved in 1924. Last previous edition approved in 2007 as E 10 – 07e1 . 2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website. 3 Available from American Bearing Manufacturers Association (ABMA), 2025 M Street, NW, Suite 800, Washington, DC 20036. 4 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org. 1 Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States. --``,,,,,,```,`,,``,``,,`,,,`-`-`,,`,,`,`,,`--- 3.1.6 Brinell hardness scale—a designation that identifies the specific combination of ball diameter and applied force used to perform the Brinell hardness test. 3.1.7 Brinell hardness testing machine—a Brinell hardness machine used for general testing purposes. 3.1.8 Brinell hardness standardizing machine—a Brinell hardness machine used for the standardization of Brinell hardness test blocks. The standardizing machine differs from a regular Brinell hardness testing machine by having tighter tolerances on certain parameters. 3.1.9 force-diameter ratio—a number calculated as the ratio of the test force in kgf to the square of the indenter ball diameter in mm (see Table 1). 3.2 Equations: 3.2.1 The Brinell hardness number is calculated as: HBW 5 2Fkgf pD~D – =D2 – d2! (1) where: Fkgf = test force in kgf, D = diameter of the indenter ball in mm, and d = measured mean diameter of the indentation in mm (see Table 1). 3.2.2 The repeatability R in the performance of a Brinell hardness machine at each hardness level, under the particular verification conditions, is estimated by the range of diameter measurements of n indentations made on a standardized test block as part of a performance verification, defined as: R 5 dmax – dmin (2) where: dmax = mean diameter of the largest measured indentation, and dmin = mean diameter of the smallest measured indenta- tion. 3.2.3 The average H of a set of n Brinell hardness measure- ment values H1, H2, ..., Hn is calculated as: H 5 H1 1 H2 1 ... 1 Hn n (3) 3.2.4 The error E in the performance of a Brinell hardness machine at each hardness level is determined as: E 5 H – HSTD (4) where: H (Eq 3) = average of n hardness tests H1, H2, ..., Hn made on a standardized test block as part of a performance verification, and HSTD = certified average hardness value of the stan- dardized test block. 3.2.5 The mean diameter of an indentation d is calculated as: d 5 d1 1 d2 1 ... 1 dn n (5) Where: d1, d2, ..., dn = measured indentation diameters in mm, and n = the number of diameter measurements. 3.2.6 The average mean diameter d of a set of indentations is calculated as: d 5 d1 1 d2 1 ... 1 dN N (6) where: d1, d2, ... dN = mean indentation diameters in mm, and N = number of indentations (see Annex A4). 4. Significance and Use 4.1 The Brinell hardness test is an indentation hardness test that can provide useful information about metallic materials. This information may correlate to tensile strength, wear resis- tance, ductility, or other physical characteristics of metallic materials, and may be useful in quality control and selection of materials. 4.2 Brinell hardness tests are considered satisfactory for acceptance testing of commercial shipments, and have been used extensively in industry for this purpose. 4.3 Brinell hardness testing at a specific location on a part may not represent the physical characteristics of the whole part or end product. 5. Principles of Test and Apparatus 5.1 Brinell Hardness Test Principle—The general principle of the Brinell indentation hardness test consists of two steps (see Fig. 1). 5.1.1 Step 1—The indenter is brought into contact with the test specimen in a direction perpendicular to the surface, and the test force F is applied. The test force is held for a specified dwell time and then removed. TABLE 1 Symbols and Designations Symbol Designation D Diameter of the ball, mm F Test force, N Fkgf Test force, kgf Fkgf 5 1 gn 3 F where gn is the acceleration due to gravity. gn = 9.80665 kgf/N d Mean diameter of the indentation, mm d 5 d1 1 d2 1 ... 1 dn n where d1 + d2 + ... + dn are the measured indentation diameters in mm, and n is the number of diameter measurements. h Depth of the indentation, mm h 5 D – =D2 – d2 2 Force- Diameter ratio 5 Fkgf D2 HBW Brinell hardness 5 Test Force Surface area of indentation 5 2Fkgf p D ~D – =D2 – d2! E 10 – 07a 2 - - ` ` , , , , , , ` ` ` , ` , , ` ` , ` ` , , ` , , , ` - ` - ` , , ` , , ` , ` , , ` - - - 5.1.2 Step 2—The diameter of the indentation is measured in at least two directions perpendicular to each other. The Brinell hardness value is derived from the mean of the diameter measurements. 5.2 Brinell Testing Machine—Equipment for Brinell hard- ness testing usually consists of a testing machine, which supports the test specimen and applies an indenting force to a ball in contact with the specimen, and a system for measuring the mean diameter of the indentation in accordance with the Brinell hardness test principle. The design of the testing machine shall be such that no rocking or lateral movement of the indenter or specimen occurs while the force is being applied. The design of the testing machine shall ensure that the force to the indenter is applied smoothly and without impact forces. Precautions shall be taken to prevent a momentary high test force caused by the inertia of the system, hydraulic system overshoot, etc. 5.2.1 See the Equipment Manufacturer’s Instruction Manual for a description of the machine’s characteristics, limitations, and respective operating procedures. 5.2.2 Anvils—An anvil, or specimen support, should be used that is suitable for the specimen to be tested. The seating and supporting surfaces of all anvils should be clean and free of foreign material. Typically, anvils need only be replaced if they fail to support the test surface perpendicular to the indenter, or they are deemed unsafe. 5.2.3 Indenters—Indenters for the Brinell hardness test shall be tungsten carbide balls of four allowed diameters (1, 2.5, 5 and 10 mm). Indenters shall meet the requirements defined in Annex A3. 5.2.4 Oil, dirt, or other foreign materials shall not be allowed to accumulate on the indenter, as this will affect the test results. 5.2.5 Measurement Device—The measurement device used for the measurement of the diameter of Brinell indentations may be an integral part of the hardness machine or a separate stand-alone instrument. The allowable measurement devices are classified into two types. The Type A device includes microscopes having movable measuring lines with some type of indicator or computerized measuring system, or an image analysis system. The Type B device is a hand-held microscope (usually 203 or 403) with fixed measuring lines. 5.2.5.1 Type A Device—The acceptable minimum resolution for a Type A device shall be as given in Table 2. 5.2.5.2 Type B Device—The acceptable maximum spacing between the graduated lines of Type B devices shall be as given in Table 2. Type B devices shall not be used for measuring indentations made with 2.5 mm and 1 mm ball indenters. 5.3 Verification—Brinell testing machines and indentation measurement devices shall be verified periodically in accor- dance with Annex A1. 5.4 Test Blocks—Test blocks meeting the requirements of Annex A4 shall be used to verify the testing machine in accordance with Annex A1. 5.5 Brinell Hardness Scales—The combinations of indent- ers and test forces define the Brinell hardness scales. The standard Brinell hardness scales and test forces are given in Table 3, corresponding to force-diameter ratios (see Table 1) of 1, 1.25, 2.5, 5, 10 and 30. Brinell hardness values should be determined and reported in accordance with one of these standard scales. Other scales using non-standard test forces may be used by special agreement. Examples of other scales and the corresponding force-diameter ratio (in parentheses) are HBW 10/750 (7.5), HBW 10/2000 (20), HBW 10/2500 (25), HBW 5/187.5 (7.5), and HBW 5/500 (20). 5.6 Calculation of the Brinell Hardness Number—The Brinell hardness number shall be calculated from the mean FIG. 1 Principle of Test TABLE 2 Resolution and Graduation Spacing of Indentation Measuring Devices Type A Type B Ball Diameter mm Minimum Indicator Resolution mm Maximum Graduation Spacing mm 10 0.0100 0.100 5 0.0050 0.050 2.5 0.0025 – 1 0.0010 – TABLE 3 Test Conditions and Recommended Hardness Range Brinell Hardness Scale Ball Diameter D mm Force- Diameter RatioA Nominal Value of Test Force, F Recommended Hardness Range HBWN kgf HBW 10/3000 10 30 29420 3000 95.5 to 650 HBW 10/1500 10 15 14710 1500 47.7 to 327 HBW 10/1000 10 10 9807 1000 31.8 to 218 HBW 10/500 10 5 4903 500 15.9 to 109 HBW 10/250 10 2.5 2452 250 7.96 to 54.5 HBW 10/125 10 1.25 1226 125 3.98 to 27.2 HBW 10/100 10 1 980.7 100 3.18 to 21.8 HBW 5/750 5 30 7355 750 95.5 to 650 HBW 5/250 5 10 2452 250 31.8 to 218 HBW 5/125 5 5 1226 125 15.9 to 109 HBW 5/62.5 5 2.5 612.9 62.5 7.96 to 54.5 HBW 5/31.25 5 1.25 306.5 31.25 3.98 to 27.2 HBW 5/25 5 1 245.2 25 3.18 to 21.8 HBW 2.5/187.5 2.5 30 1839 187.5 95.5 to 650 HBW 2.5/62.5 2.5 10 612.9 62.5 31.8 to 218 HBW 2.5/31.25 2.5 5 306.5 31.25 15.9 to 109 HBW 2.5/15.625 2.5 2.5 153.2 15.625 7.96 to 54.5 HBW 2.5/7.8125 2.5 1.25 76.61 7.8125 3.98 to 27.2 HBW 2.5/6.25 2.5 1 61.29 6.25 3.18 to 21.8 HBW 1/30 1 30 294.2 30 95.5 to 650 HBW 1/10 1 10 98.07 10 31.8 to 218 HBW 1/5 1 5 49.03 5 15.9 to 109 HBW 1/2.5 1 2.5 24.52 2.5 7.96 to 54.5 HBW 1/1.25 1 1.25 12.26 1.25 3.98 to 27.2 HBW 1/1 1 1 9.807 1 3.18 to 21.8 A See Table 1. E 10 – 07a 3 - - ` ` , , , , , , ` ` ` , ` , , ` ` , ` ` , , ` , , , ` - ` - ` , , ` , , ` , ` , , ` - - - diameter d of the indentation using Eq 1 or from the values given in Appendix X1. 5.6.1 Brinell hardness values shall not be designated by a number alone because it is necessary to indicate which indenter and which force has been employed in making the test (see Table 3). Brinell hardness numbers shall be followed by the symbol HBW, and be supplemented by an index indicating the test conditions in the following order: 5.6.1.1 Diameter of the ball, mm, 5.6.1.2 A value representing the test force, kgf, (see Table 3) and, 5.6.1.3 The applied force dwell time, s, if other than 10 s to 15 s. 5.6.2 The only exception to the above requirement is for the HBW 10/3000 scale when a 10 s to 15 s dwell time is used. Only in the case of this one Brinell hardness scale may the designation be reported simply as HBW. 5.6.3 Examples: 220 HBW = Brinell hardness of 220 determined with a ball of 10 mm diameter and with a test force of 29.42 kN (3000 kgf) applied for 10 s to 15 s 350 HBW 5/750 = Brinell hardness of 350 determined with a ball of 5 mm diameter and with a test force of 7.355 kN (750 kgf) applied for 10 s to 15 s 600 HBW 1/30/20 = Brinell hardness of 600 determined with a ball of 1 mm diameter and with a test force of 294.2 N (30 kgf) applied for 20 s 6. Test Piece 6.1 There is no standard shape or size for a Brinell test specimen. The test piece on which the indentation is made should conform to the following: 6.1.1 Thickness—The thickness of the specimen tested shall be such that no bulge or other marking showing the effect of the test force appears on the side of the piece opposite the indentation. The thickness of the material under test should be at least ten times the depth of the indentation h (see Table 4). Table 4 can also be used as a guideline for the minimum depth of a layer of a material, such as a coating. NOTE 1—Brinell hardness testing can use high test forces. Under certain conditions of testing a relatively thin material or coating on a material with high hardness, there is a potential for the test material to break or shatter under load resulting in serious personal injury or damage to equipment. Users are strongly cautioned to exercise extreme care when testing a material that could potentially fail under load. If there is a concern or doubt, do not test the material. 6.1.2 Width—The minimum width shall conform to the requirements for indentation spacing. 6.1.3 Finish—When necessary, the surface on which the indentation is to be made should be filed, ground, machined or polished flat with abrasive material so that the edge of the indentation can be clearly defined to permit the measurement of the diameter to the specified accuracy. Preparation shall be carried out in such a way that any alteration of the surface hardness of the test surface (for example, due to overheating or cold-working) is minimized. 7. Test Procedure 7.1 The diameter of the indentation shall be between 24 and 60 % of the ball diameter. Approximate Brinell hardness numbers are given in Table 3 for the above range of indentation diameters. NOTE 2—A lower limit in indentation diameter is necessary because of the risk in damaging the ball and the difficulty in measuring the indentation. The upper limit is necessary because of a reduction in sensitivity as the diameter of the indentation approaches the ball diameter. The thickness and spacing requirements may determine the maximum permissible diameter of indentation for a specific test. NOTE 3—It is not mandatory that Brinell tests conform to the hardness scales of Table 3. It should be realized that different Brinell hardness numbers may be obtained for a given material by using different forces on the same size of ball. For the purpose of obtaining a continuous scale of values, it may be desirable to use a single force to cover the complete range of hardness for a given class of materials. 7.2 The Brinell hardness test is not recommended for materials above 650 HBW 10/3000. 7.3 Direct comparisons of Brinell hardness numbers for tests using different scales can be made only if the force- diameter ratio is maintained (see Table 3). Brinell hardness tests made on the same test material, but using different force- diameter ratios, will produce different Brinell hardness num- bers. 7.3.1 Example—An HBW 10/500 test will usually approxi- mate an HBW 5/125 test since the force-diameter ratio is 5 for both scales. However, a value of 160 HBW 10/500 will be TABLE 4 Minimum Specimen Thickness Based on Ten-Times the Indentation Depth Diameter of Indentation, d Minimum Specimen Thickness 10 mm Ball 5 mm Ball 2.5 mm Ball 1 mm Ball mm mm in. mm in. mm in. mm in. 0.2 0.1 0.004 0.3 0.2 0.009 0.4 0.4 0.016 0.5 0.7 0.026 0.6 0.4 0.014 1.0 0.039 0.7 0.5 0.020 0.8 0.7 0.026 0.9 0.8 0.033 1.0 1.0 0.041 1.1 1.3 0.050 1.2 0.7 0.029 1.5 0.060 1.3 0.9 0.034 1.8 0.072 1.4 1.0 0.039 2.1 0.084 1.5 1.2 0.045 2.5 0.098 1.6 1.3 0.052 1.7 1.5 0.059 1.8 1.7 0.066 1.9 1.9 0.074 2.0 2.1 0.082 2.2 2.6 0.100 2.4 1.5 0.058 3.1 0.121 2.6 1.7 0.068 3.6 0.144 2.8 2.0 0.079 4.3 0.169 3.0 2.3 0.091 5.0 0.197 3.2 2.6 0.104 3.4 3.0 0.117 3.6 3.4 0.132 3.8 3.8 0.148 4.0 4.2 0.164 4.2 4.6 0.182 4.4 5.1 0.201 4.6 5.6 0.221 4.8 6.1 0.242 5.0 6.7 0.264 5.2 7.3 0.287 5.4 7.9 0.312 5.6 8.6 0.338 5.8 9.3 0.365 E 10 – 07a 4 - - ` ` , , , , , , ` ` ` , ` , , ` ` , ` ` , , ` , , , ` - ` - ` , , ` , , ` , ` , , ` - - - approximately equal to 180 HBW 10/3000 on the same test material because of different force-diameter ratios (5 and 30, respectively). 7.4 Daily Verification—A daily verification of the testing machine shall be performed in accordance with Annex A1 prior to making hardness tests. It is also recommended that the operation of the machine be checked in acc