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Laurence Brice, Samuel Low, Rodney Jiggetts
DETERMINATION OF SENSITIVITY COEFFICIENTS FOR ROCKWELL HARDNESS SCALES HR15N, HR30N, AND HRA

This report describes the work carried out to provide sensitivity coefficients for the Rockwell HRA and Superficial Rockwell HR15N and HR30N scales. Sensitivity coefficients were determined for the preliminary test force, total test force, force duration times, loading times, and loading rates.
Work was carried out at both the National Physical Laboratory (NPL) in Teddington, UK and the National Institute of Standards and Technology (NIST) in Gaithersburg, USA.

A. Stibler, K. Herrmann
ESTIMATION OF UNCERTAINTY IN HARDNESS MEASUREMENT OF RUBBER AND OTHER ELASTOPLASTIC MATERIALS

In this paper the approach and results for the estimation of uncertainty in measurements of rubber and plastics are presented. The developed uncertainty guidelines are based on "Guide to the Expression of Uncertainty in Measurement" (ISO GUM). As the most important and widely used hardness measuring methods for rubber and plastics the methods according to Durometer (A and D) and to the International Rubber Hardness Degree (IRHD), scales N, M and L are dealt with. Additionally a new hardness measuring method for soft silicones, called Hardness Very Low (HVL), which is still in the process of standardization, is considered. According to the calibration methods direct calibration of test force, indentation depth and geometrical deviations of indenters must be carried out. Correspondingly the uncertainty of these direct calibrations have to be determined. In order to indicate the uncertainty based on these direct calibration expressed in hardness units, it is necessary to summarize the uncertainties of the direct calibration with the aid of sensitivity coefficients. Further, indirect calibrations with reference test blocks also require to indicate the uncertainty in hardness units.

G. W. Bahng, Colin Lea
ESTABLISHMENT OF A TRACEABILITY CHAIN IN METROLOGY FOR MATERIALS

Materials metrology is becoming an increasingly important international issue, with the worldwide efforts to realize a free trade agreement. The establishment of a traceability chain in materials metrology is, however, difficult because the measurement of materials properties is commonly procedure-dependent. This means that the establishment of a traceability chain in measurement of materials properties is not so straightforward as in physical measurement. In fact, three essential components, namely reference procedure, reference machine, and reference materials, are required to establish a traceability chain in materials metrology. In this paper, strategies to establish a traceability chain in metrology for materials are discussed to provide comparability amongst testing laboratories.

G. Aggag, A. Abu-Elezz
EFFECT OF LOADING RATE AND DURATION TIME ON INDENTATION HARDNESS MEASUREMENTS

Previews studies on the effect of loading rate on the micro and nano indentation hardness showed that both of them affect hardness measurements. Such effect has been included in micro and nano hardness measurements. ISO/FDIS 14577-1 standard determine the loading rate of the indenter for micro hardness showed not exceed 2 µm/sec and for nano hardness should be less then 10 nm/sec. The present study is a trial to reveal the effect of both loading rate and duration time on the macro indentation hardness applied on standard hardness test blocks. A modern Zwick hardness tester that could vary loading rates and duration time over a broad range was used to preform this study. The study showed that a safe loading rate should not exceed 10 µm/sec. It also showed an obvious effect of duration time on the hardness value. It is recommended that the duration value should be stated clearly in such hardness measurement.

Robert Ellis, Andy Knott, Konrad Herrmann
VERIFICATION OF IMAGE ANALYSIS SYSTEMS FOR MEASURING BRINELL INDENTATIONS

Recently image analysis systems have become available and are now used widely in industry. While there are great benefits in using this method to measure Brinell hardness indentations, a method to verify these systems is needed. Older methods using flat stage micrometers exclusively are not sufficient. Methods and guidelines for the use of these systems should be developed.

Jiong-Shiun Hsu, Chi-Shen Chang, Yu-Yi Su, Jeah-Sheng Wu, Sheau-Shi Pan
UNCERTAINTY EVALUATION OF THE NANOINDENTATION SYSTEM

In this paper, the uncertainty of nanoindentation system was evaluated. The laser interferometer and electronic balance were respectively adopted to calibrate the quantities of displacement and load of nanoindeantion system. The results reveal that the relative expanded uncertainty of indeantion hardness, UH, is 8.1%. The relative expanded uncertainity of reduced modulus, UEr, is 5.4%.

Takeshi Sawa, Masaharu Tsujii, Masaru Kawazoe
INSTRUMENTED INDENTATION TEST FOR HIGH-TEMPERATURE SPECIMEN

Concerning the specimen heating table attached to an instrumented indentation testing machine, one of the hardness testing machines, for realizing the hardness test of heated specimen, thermal influences to the instrumented indentation testing machine by attaching the specimen heating table have been examined. Consequently, it has been clarified that test result errors are mainly induced by the fact that the thermal expansion by the increase in temperature of the indenter (the metal part fixing the diamond tip) is added to the measured indentation depth, so that the accurate indentation depth cannot be measured. Furthermore, it has been considered that the increase in temperature of the indenter is mainly caused by the thermal transfer (thermal conduction) while the indenter contacts with the hightemperature specimen, and it has been clarified that the behavior of temperature change of the indenter depends on specimen materials and testing conditions. In this paper, newly invented measures for obtaining correct indentation depth in high-temperature tests are described.

Harald Kohlhoff, Christian Ullner
DESIGN AND CAPABILITY OF A NEW CALIBRATION MACHINE FOR THE MACRO RANGE OF INSTRUMENTED INDENTATION TEST

The instrumented indentation test provides a versatile method to determine several materials parameter. In order to provide reference specimens, a calibration machine according to ISO 14577-3 is designed for the macro range. Using innovative technology, the new machine design may lead to a standard solution not only for calibration machines.

Christian Ullner, Erhard Reimann
EFFECT AND MEASUREMENT OF THE MACHINE COMPLIANCE IN THE MACRO RANGE OF INSTRUMENTED INDENTATION TEST

The contribution concerns the dominant source of uncertainty in the upper macro range of the instrumented indentation test. The strong effect of the machine compliance is demonstrated (including for machines with a displacement measurement which is related to the surface of the specimen). Four methods are applied for analyzing the experimental results up to 2500 N. The results show that the uncertainty of the compliance should be limited in ISO 14577 part 3.

J.A. Cruz, R.R. Machado, S.P. Oliveira. A.R. Martins, A.C. Vidal, J.A.S. Pereira, I. Caminha, I. Abud , C. Barbosa
ESTABLISHMENT OF A HARDNESS METROLOGICAL SYSTEM IN BRAZIL

In the present work, part of a large project, developed in partnership among INMETRO, ITUC/PUCRio and INT since 1995, to establish a national hardness metrological system in Brazil to Brinell, Vickers and Rockwell hardness scales, is presented, e.g. the development of reference blocks, for different ranges of Rockwell B and C hardness scales. These results and the installation of a hardness standardization machine and an indenter calibration system at INMETRO will fill the existing voids up in the Brazilian traceability chain in hardness metrology.

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