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ASTM E92 PDF

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1 This test method is under the jurisdiction of ASTM Committee E on. Mechanical Originally published as E 92 - 52 T. Last previous edition E( ). E Standard Test Methods for Vickers Hardness and Knoop Hardness of Metallic Materials Standard + Redline PDF Bundle, 54, $, ADD TO CART . ASTM E - Vickers Hardness of Metallic Materials(1) ASTM E8M Standard Test Methods for Tension Testing of Metallic Materials. ASTM E_E Vickers Knoop.


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ASTM Epdf - Download as PDF File .pdf), Text File .txt) or read online. This standard is issued under the fixed designation E92; the number immediately 1 These test methods are under the jurisdiction of ASTM Committee E28 on. ASTM E92 Vickers Hardness Test consists of a small pyramid shaped diamond indenter with an apical angle of °, which is pressed into the test sample at a.

Requirements for the optical metallograph apparatus and specimen preparation including polishing and etching are detailed. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

ASTM E92 - 17

Please login to your authorized staff account to use this feature. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every ve years and if not revised, either reapproved or withdrawn. There were no books found for the applied search filters. Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. Procedure for Evaluation 6.

ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date. Higher x indicate a larger number or greater degree of severity of the category being rated. It does not establish limits of acceptability. When critical or detailed analysis of structures is axtm, the recommended etchant is Picral saturated. This abstract is a brief summary of the referenced standard. An example rating is: This guide covers the definition and rating of the microstructure of carbide structures in astk high carbon bearing steels.

It is aastm only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. The description of the reference photomicrographs graded illustrations of annealed carbides categorized by size, network, and lamellar content shape that shall be used in the evaluation and the equation that shall define the rating are given. The rating will be the number of that photo which most closely resembles the appearance of the specimen.

It is informational only and not an official part of the standard; the full text a the standard itself must be referred to for its use and application. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters. A mid-range block was chosen for the gf test force A1. The user may perform the verification by following 0.

ASTM E92 - 17

Two test blocks are chosen for the the as-found procedures given in A1. If the repeatability R verification: In this case, the highest test force gf is used on Table A1.

Three test blocks are chosen for the not recommended. In these situations, the indentation measure- verification: In this case, the highest test force 5 length. This can lead to substantial deviations in hardness from kgf is used on a low-range hardness block, and the lowest test the stated value.

If possible, a block hardness should be used force 1 kgf is used on the high-range test block. Let d1, d2, Hardness measurements shall be made only on the between indirect verifications. At a minimum, the periodic calibrated surface of the test block. Determine the repeatability verification shall be performed in accordance with the schedule R and the error E in the performance of the testing machine given in Table A1.

ASTM A892 – 09(2014)e1

The repeatability R A1. Table A1. Repeatability R Calculation—Assume that five and Knoop hardness scale that will be used. At least one Knoop indentations were made on a test block with a nominal standardized test block that meets the requirements of Annex hardness of HK at the certified block test force of gf A4 shall be used for each Vickers and Knoop hardness scale to and that the five diagonal measurements are When test blocks are commercially available, the According to mately the same hardness value as the material to be measured.

In this example, the testing tion shall be the indenter that is normally used for testing. However, if these diagonals had been obtained ensure that the testing machine is working freely, the stage and using a test block with a nominal hardness of HK and a test block are clean, and the measuring device is properly certified test force of gf, then the repeatability would be adjusted and zeroed. Error E Calculation—The following example of quirements given in 7.

Hardness measurements shall be an error calculation is based on the measurement data given in made only on the calibrated surface of the test block. Determine the error E in the performance of the testing be kept of the periodic verification results, including the machine using Eq 3 for each standardized test block that is verification date, measurement results, certified value of the measured.

These within the tolerances given in the applicable Table A1. The testing machine information when available as a result of the verification with the indenter may be regarded as performing satisfactorily performed. Historical hardness value is within the error range. From E92 and continue to be within the verification schedule given Table A1.

This is equivalent to HV 0. The periodic verification is acceptable when the measured average diagonal length or equivalent HV value is A1. If the average of standard. Measurements made to determine verification or periodic verification may be suspect. A verification report is not required for a verification. The hardness stan- to the requirements of ISO or an equivalent by an dardizing machine differs from a hardness testing machine by accrediting body recognized by the International Laboratory having tighter tolerances on certain performance attributes Accreditation Cooperation ILAC as operating to the require- such as force application and indenter geometry.

An agency accredited to perform izing machine is used for the standardization of test blocks as verifications of hardness standardizing machines may perform described in Annex A4. The A2. It is A2.

NOTE A2. When standardiza- identification of standards to which traceability is made. Measure- A2. It is recommended that the uncertainty in the calculated A2. The test force dwell time shall be izing machine, when applicable. The difference between the reading device A2. The instruments A3. Table A3. Class B indenters are intended for everyday use with hardness A3. The four faces of the standardization of test blocks in accordance with Annex A4. When testing with forces less than 1 kgf, the offset shall not A3.

The standard- izing laboratory shall have a certificate of accreditation stating A3. The face angles shall be equally inclined to the axis of the standard, except as stated below. The two angle A highly polished, pointed, rhombic-based, pyramidal diamond. Angles A and B 0. For shorter indentations the offset should A3. See A3. Class B Knoop indenter as given in A3. The offset shall not exceed 0.

When it is not A3. The mean, centerline average, surface rough- A4. Cleaning of the tion of the performance of Vickers and Knoop testing machines polished test block surface is often required in normal usage by way of periodic verifications and indirect verifications as but must not alter the hardness or quality of the polished test described in Annex A1.

When more which the test block standardizations are traceable. E are considered to satisfy the accreditation requirements A4. Record the data by location and by block. Determine the repeatability R of shall be chosen to produce the required degree of homogeneity, the calibration measurements using Eq 2. The repeatability R is structural stability and uniformity of hardness at the prepared an indication of the hardness homogeneity of the test block, surface. The repeatability R shall be within the manufacturer and shall be maintained in that condition by the tolerances of the applicable Table A4.

The mea- A4. The as a standardized test block. See A4. Example A5. The procedure described in approach to evaluating the uncertainty of Vickers and Knoop section X1.

The user may report the verification, a number of hardness measurements are made on uncertainty value with the measurement value. Determining the uncer- X1. This in this appendix considers only those uncertainties associated is done to provide a method that is based on familiar procedures and with the overall measurement performance of the Vickers or practices of Vickers and Knoop hardness users and standardizing agencies. Knoop hardness machine with respect to reference standards.

The reader should be aware that there are other methods that may be employed to determine the same uncertainties, which may provide more These performance uncertainties reflect the combined effect of accurate estimations of the uncertainty values. Therefore, the A1. These limit values were originally established based on the testing experience of many users of the Vickers and Knoop machine are not included in the calculations. Because of this hardness tests, and therefore reflect the normal performance of a properly approach, it is important that the individual machine compo- functioning Vickers or Knoop hardness machine, including the normal nents are operating within tolerances.

Because the limits are based on testing experience, it is believed that the stated limit values take into account a level of uncertainty passing a direct verification. The dures and schedules of this test method standard. NOTE X1. The experience. The tolerance values reflect the normal performance of a principal difference is in the hierarchy level of the reference properly functioning Vickers and Knoop hardness machines, including the test blocks normally used for the indirect verification.

For these products, the stated tolerance limits take into account a Generally, standardizing machines are verified using primary level of uncertainty that is typical for valid Vickers and Knoop hardness reference standards, and testing machines are standardized measurements. Consequently, when acceptance testing most products for using secondary reference standards. There may be exceptional circumstances where the hardness of of uncertainty must be determined.

Because many of the a product must fall within determined ranges to a high level of confidence. Before such an agreement is made, it tainty should be determined for each hardness scale and is recommended that the product design take into consideration the hardness level of interest.

In many cases, a single uncertainty anticipated influence of material and metallurgical factors on the product value may be applied to a range of hardness levels based on the variation as well as typical industry hardness uncertainty values.

In some cases, the X1. For X1. When test systems are not corrected for measure- uniformity in the hardness of the test material are difficult to ment bias, as often occurs in Vickers and Knoop hardness separate and must be determined together. The uncertainty testing, the bias then contributes to the overall uncertainty in a contributions for each of these circumstances may be estimated measurement.

There are a number of possible methods for as follows. A simple and single hardness measurement, the standard uncertainty contri- conservative method is to combine the bias with the calculation bution uRepeat, due to the lack of repeatability, may be esti- of the expanded uncertainty as: In general, the estimate of repeatability is improved as the number of and express measurement uncertainty, a brief description of hardness measurements is increased.

Usually, the hardness what the reported uncertainty values represent should be values measured during an indirect verification will provide included with the reported uncertainty value. It may be more appro- X1. The calculations of the uncer- measurement uncertainty for the three measurement circum- tainty uRepeat and of the historically defined repeatability do not produce stances described in X1.

The uncertainty uRepeat is the contribution to the overall X1. When evaluating repeatability as discussed above, any uncer- test block standards. An estimation of the measurement bias tainty contribution due to the hardness non-uniformity should be mini- and its inclusion into the expanded uncertainty will also be mized as much as possible.

The laboratory should be cautioned that if the discussed. Imagine there is a material, which average of multiple hardness test values is to be due reported, is perfectly uniform in hardness over its entire surface.

ASTM E92.pdf

Even ously calculated from a number of hardness measurements though the actual hardness of every test location is exactly the made on a uniform test specimen, see X1. For example, this may be done when u Resol 5 5 X1. It is important to note that the resolution a test block. When the converted to the resolution in hardness units as: This is indentation would yield the same measurement value, indicating that the calculated as the standard deviation of the hardness values, measurement uncertainty due to the lack of repeatability in the ability to measure the indentation diagonal length would be negligent or zero.

However, this is probably not the case.

The resolu- tion contributions are also dependent on the type of measurement system X1. In most cases, a Vickers or Knoop indentation diagonal length is uReprod —The day-to-day variation in the performance of the measured by locating and resolving the indentation tips at each end of the hardness machine is known as its level of reproducibility.

The ability of the measuring system to resolve the indentation tip Variations such as different machine operators and changes in is partly due to the incremental resolution of the system, but also due to the optical resolution of the microscope objective. In the case of video the test environment often influence the performance of the measurement systems, the incremental resolution may be based on the hardness machine.

The level of reproducibility is best deter- incremental length spacing observed on the sample corresponding to two mined by monitoring the performance of the hardness machine adjacent video display pixels, or how the measurement software resolves over an extended period of time during which the hardness the video image.

In the case of using an optical microscope with a filar machine is subjected to the extremes of variations in the testing eyepiece, the incremental resolution may be based on the resolution of the measurement display or micrometre scale.

The resolution of the measuring variables. It is very important that the test machine be in system is also dependent on the resolution of the microscope objective control during the assessment of reproducibility. If the machine based on the wavelength of light used to observe the indentation and the is in need of maintenance or is operated incorrectly, the lack of numerical aperture of the lens see 7. To determine the overall measurement uncertainty due to the measure- ment resolution, both the uncertainties due to the incremental resolution of X1.

The uResol incr and uResol obj using Eq X1. Since the measurement of a diagonal length deviation of the average of each set of monitoring values, as: For a Knoop or Vickers hardness measurement, n sets of multiple monitoring measurement values. The certificate accompanying estimate the reproducibility uncertainty.

This tation measuring system prevents the hardness machine from uncertainty contributes to the measurement uncertainty of providing an absolutely accurate hardness value. The uncer- hardness machines calibrated or verified with the reference test tainty contribution uResol, due to the influence of the measuring blocks.

This analysis uses the standard uncertainty and hardness level of each Vickers and Knoop hardness scale as: The value of UMach should be supplemented with a statement X1. Since there is always uncer- X1.

An evaluation will only be hardness measurement error, uMach, are: Block , the uncertainty due to the lack of a reported certified value of HK 0. The agency block Eq X1.

The five measurements made on a reference test block to determine the diagonal measurements are The notation Ref. Block is Blockd U Mach Although this evaluation was the single and average hardness values only represents the made on material having a hardness of approximately HK uncertainties of the measurement process and are independent 0.

Think Form

This calculation must be made for the low and high ranges of the HK 0. Usually, was done between steps. Consequently, if individual equations are solved multiple hardness measurements are made across the surface of using the rounded values that are given at each step of this example, some the test piece, and then the average of the hardness values is computed results might differ in value in the last decimal place from the reported as an estimation of the average hardness of the results stated.

If it is desired to report the uncertainty as an indication of how well the average measurement value repre- X1.

Vickers and sents the true average hardness of the material, then the Knoop Hardness Measurement Values contributions to the standard uncertainty uMeas are: This analysis is essentially that the measurements were made, then this information should identical to the analysis given in X1. In this case, the product is a uncertainty was calculated. The contributions to the stan- X1. Block , the uncertainty due to the stan- hardness.

The values of the hardness measurements of the dardizing machines lack of repeatability combined with the product were , , , , and , resulting in an uncertainty due to the calibrated blocks non-uniformity Eq average value of HV 0.

The microscope used to measure X1. The laboratory would made on the test block. The notation Calib. A hardness of HV 0. The last indirect 2 UReprod, the uncertainty contribution due to the lack of verification of the mid-range of the HV 0. For this example, assume the hardness machine has been X1. Other uncertainty contributions are hardness level of each Vickers or Knoop test force and indenter calculated as: Blockd 5 be used.

The monitored for an extended period of time, and from Eq X1.This is indentation would yield the same measurement value, indicating that the calculated as the standard deviation of the hardness values, measurement uncertainty due to the lack of repeatability in the ability to measure the indentation diagonal length would be negligent or zero.

It is informational only and not an official part of the standard; the full text a the standard itself must be referred to for its use and application.

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Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility.

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade TBT Committee. Annex A2. The notation Ref. It is important to note that the resolution a test block.

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