IMEKO Event Proceedings

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Kozo Iizuka
WORLDWIDE ACTIVITIES AROUND HARDNESS MEASUREMENT - ACTIVITIES IN CCM/CIPM, IMEKO/TC5, OIML/TC10 AND ISO/TC164 -
All of hardness testing methods now in use were invented about a century ago but it was after the World War II that the international conformity of the test results was required and that the standardization of the testing methods and testing machines was investigated and promoted. In this paper, the historical role of four international organizations, CIPM, IMEKO, OIML and ISO for the progress of the standardization of hardness testing and on the development of the metrological standards of hardness is reviewed together with some remark on the discussions related to the definition of hardness as a quantity. Then a few comments on the feature and metrological meaning of hardness standards are described.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Konrad Herrmann
NEW DEVELOPMENTS AND APPLICATIONS IN HARDNESS METROLOGY
The overview on the development tendencies clarifies that the main developments refer to the increase of productivity and of the accuracy of measurements. With the development of new materials also new optimum hardness measuring methods are developed. Great efforts are undertaken to enlarge the information content of hardness measuring methods. In this connection great perspectives can be ascribed to the instrumented indentation test.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Zhi Li, Sai Gao, Konrad Herrmann
DEVELOPMENT OF A MICRO-MINIATURE NANOINDENTATION INSTRUMENT
Among the various methods for characterizing the mechanical properties of small volume of materials, nano-indentation testing has gained more and more interests, due to its simple principle, the easy realization and application for various specimen, etc. However, nano-indentation instruments often fail to measure the mechanical properties of materials which demonstrate heavy creep, plasticity, etc. To overcome the disadvantages of nano-indentation instruments, here a new approach to develop the next generation of nano-indentation systems is proposed, in which the well-developed MEMS technique is employed. As one of the key components in the to be developed system, the loading component is now realized by an electrostatic comb-drive actuator, which can generate the required indentation force with high resolution. This microminiature indentation system will feature the advantages of small size, low power consumption, high precision in manufacture, the potential for low cost through batch fabrication, the ability for on-site applications, etc. In this paper the design of the MEMS system is detailed, including the simulation of the mechanical system and the system performance.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Zhi Li, Sai Gao, Konrad Herrmann
INVESTIGATION OF NANO-INDENTATION ON FREE-STANDING FILMS FOR THE DETERMINATION OF TENSILE TEST PARAMETERS
With the aim to extract the mechanical properties of small volumes of materials, nowadays several methods have been proposed and are applied in practice. How to compare the results of these methods, therefore, gains more and more interests. Instrumented indentation with a spherical indenter on circularly supported freestanding thin films is believed to be an effective way to connect and compare the material testing methods including nanoindentation and micro-tensile testing. In this paper an experimental setup for making indents on free-standing films is presented, in which a modified bright-field microscope with optical sectioning capability is applied to determine the zero-point of nanoindentation, and to in-situ and real-timely measure the deflection of the film. Preliminary experimental results are reported, which coincide with the theoretical model.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Kensuke Miyahara, Takashi Yamamoto
TUNGSTEN SINGLE CRYSTAL AS HARDNESS STANDARD FOR NANOINDENTATION
Hardness standard of tungsten single crystal were utilized in order to check stability and reproducibility of nanoindentation testers. The pop-in load and maximum penetration depth were measured and monitored during several hundreds of repeated experiments. One of the tested instruments showed gradual increase of pop-in load and decrease of maximum depth, which indicate the indenter tip was damaged by repeated tests. The both parameters, the pop-in load and the maximum depth, can be used to detect the change of the area function; the pop-in force is more sensitive and should be easy for general users. Other applications of tungsten single crystal are also discussed.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Jiong-Shiun Hsu, Sheng-Jui Chen, Hui-Ching Lu, Shear-Shi Pan, Gwo-Jen Wu, Chung-Lin Wu, Chin-fen Tuan
UNCERTAINTY EVALUATION OF MODULUS AND HARDNESS FOR THE NANOINDENTATION MEASUREMENT SYSTEM
The uncertainties of nanoindentation measurement system were evaluated in this paper. A precise electonic balance and an optical interferometric system were respectively utilized to calibrate the force and displacement of nanoindentation measurement system. The uncertainties of reduced modulus and indentation hardness providing from the naoindentaion measurement were respectively obtained.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Harald Kohlhoff, Christian Ullner
VERIFICATION OF THE STANDARD MACHINE FOR THE MACRO RANGE OF INSTRUMENTED INDENTATION TEST
A new calibration machine according to the requirements given by ISO 14577-3 [1] was described in [2]. The results of the verification are reported in this paper. It is shown that the calibration machine can be used as a national standard for the materials parameter of the instrumented indentation test.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Min-Jae Choi1, Kyung-Woo Lee, Ju-Young Kim, Kwang-Ho Kim, Dongil Kwon
APPLICATION OF INSTRUMENTED INDENTATION TECHNIQUE TO ESTIMATE STRENGTH AND RESIDUAL STRESS
The instrumented indentation technique has recently attracted significant research interest because of its various advantages such as nondestructive specimen preparation, easy process, and high spatial resolution. In particular, this technique is a promising alternative to measurement methods of tensile properties and residual stress. We can evaluate tensile properties and residual stress by analyzing the indentation load-depth curve. Tensile properties of materials, primarily yield strength and tensile strength, are obtained by defining representative stress and strain, through the numerous investigations of instrumented indentation curves, and the results were discussed by comparing with results of uniaxial tensile tests. Residual stress measurement technique is based on the key concepts that the deviatoric stress part of residual stress affects the change in indentation load-depth curve, and then by analyzing difference between residual stress-induced indentation curve and residual stress-free curve, quantitative residual stress of target region can be evaluated. In determining the stress-free curve of the target region, we take into consideration microstructural changes accommodating the strength difference. Micromechanical contact analyses for the residual-stress-induced load shifts yield stress values comparable to the applied in-plane stresses. This study supports the proposition that the surface stress in an arbitrary biaxial state can be evaluated through a theoretical model combined with the ratio of two principal stress components. Instrumented indentation tests and conventional tests were performed to verify the applicability of the suggested technique, and the estimated residual stress values obtained from the indentation technique showed good agreement with those from conventional tests.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Motofumi Ohki, Tatsuya Ishibashi, Jun Kinoshita, Hiroki Uchiyama
APPLICATION OF INDENTATION TEST TO THE EVALUATION OF TBC YOUNG’S MODULUS
Thermal barrier coatings (TBCs) have been applied to vanes / blades of gas turbines for recent electric power stations and these contribute to the efficiency of gas turbines. Measurement of Young’s modulus of the top-coat of TBCs with high accuracy is important since it is a dominant factor for determining the magnitude of thermal stress. However, until now, evaluation method for Young’s modulus of the top-coat has not been established, due to difficulty of material testing in its coated form. Furthermore, a porosity of the top-coat is changed by progress of sintering phenomenon caused by long-term high temperature exposure in air, consequently Young’s modulus of the topcoat is also influenced. In this study, various trials to evaluate Young’s modulus of the top-coat for application of the indentation test were conducted. Firstly, both dependency of the testing load and anisotropy on calculated Young’s modulus of the top-coat were discussed. Next, measurement of Young’s modulus of the top-coat after long-term high temperature exposure was carried out. Obtained results were verified by comparing with other method to measure Young’s modulus of the top-coat.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Yusuke Yoshikawa, Shigeo Katayama, Satoshi Takagi, Tatsuya Ishibashi, Motofumi Ohki
DIFFERENCES OF PERFORMANCE BETWEEN THE STEEL STANDARD BLOCKS FOR HARDNESS MADE IN JAPAN AND THAT IN GERMANY IN THE DISPLACEMENT RANGE FROM NANO TO MICROMETER
Even though the efforts have been made to develop an ideal hardness testing machine, it is inevitable that the difference of performance between the models (or types) of testing machine significantly affect the test results especially in the range of nanoindentation. The hardness reference blocks can be used to compensate the unreliability of machines by evaluating the difference between machines. The performance of hardness reference blocks should be considered from various aspects, e. g., repeatability and uniformity of parameters such as HM or HIT, easy handling, durability of testing, the dimensions and the price. Due to the large amount of usage in the world industry, the hardness reference blocks of Japanese manufacturer (HMV900, HMV500, UMV500, UMV700 of YSTL) and German manufacturer (HV840 and HV540 of Buderus) are chosen in this report and tested by using PICODENTER HM500 nanoindentation machine of Helmut Fischer, which can cover the displacement range of pico- to micrometers.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Rugkanawan Kongkavitool, Satoshi Takagi, Takashi Usuda
TEST-LOCATION SPECIFICATION BY MEANS OF HARDNESS MAPPING ON VICKERS BLOCK SURFACE
The non-uniformity of the hardness reference block is one of the important factors, which influence the hardness measurement. For calibration of hardness reference block, the elementary idea to reduce the error from this factor is to make the indentations at the distributed location as though covering the entire test surface with limited number of indentations. The principle to decide the appropriate numbers and locations of the measurement is to consider the trend and frequency of hardness distribution. “Stratified sampling” was introduced to the study on the assumption that the confidence of average hardness estimation would be increase with an appropriate test location. Six Vickers hardness reference blocks of 200, 600, 900 HV from 2 different manufacturers were selected for the experiment. The numbers of indentations were made on the entire surface of all blocks with three different levels of the test force. The analysis of hardness distributions was carried out with their measurement data with several aspects of the study. The possible trends of hardness distribution of the blocks, which, considered in the study i.e., circumferential divisions and radial divisions were selected to view the difference in hardness variation. The effect of stratified conditions to the measurement result was judged by using the analysis of variance (ANOVA). In most case of the experimental results, both stratifying conditions had significant influences on the reference blocks from both manufacturers with the different trends. Therefore, for higher confidence of hardness number estimation, the idea of test location specification should be taken into account by a considering of both stratifying conditions. Basically, the minimum numbers of indentations that give the reproducible hardness value upon the repeated measurement is desirable. By varying the stratifying conditions, the observed variations in hardness tended to decrease with the increasing number of strata. From the experiment, more than 6 to 12 strata were recommended for reliable hardness reference block measurement whereas 5 indentations were required as the minimum number in ISO 6507 part 3 [1].
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Samuel Low, Rodney Jiggetts
RECENT CHANGES AND ADDITIONS TO THE HARDNESS TEST METHODS DEVELOPED AND PUBLISHED BY ASTM-INTERNATIONAL
Since the mid 1990s, several factors have influenced the standards development organization ASTMInternational to make changes and additions to their published hardness test method standards. These factors included the advent of laboratory quality systems and the resulting need for uncertainty analysis; technological advances in testing equipment and measurement methods; and the recognition that improvement to the methods could be made. The result has been to improve the existing standards and develop new standards to meet evolving needs of industrial users. Some of the more important changes and additions to the ASTM-International hardness standards are discussed.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Li Ma, Sam Low, John Song
INVESTIGATION OF BRINELL INDENTATION DIAMETER FROM CONFOCAL MICROSCOPE MEASUREMENT AND FEA MODELING
Significant measurement differences have been continually observed worldwide in Brinell hardness tests, even in the secondary calibration laboratories that calibrate test block reference standards. The main cause of this problem is the edge of the indentation is not a distinct boundary, but is instead a curved surface from either material piling up (pile-up) or sinking in (sink-in) caused by plastic flow of the material surrounding the ball indenter. This makes it difficult to clearly resolve the edge of the indentation and thus determine the indentation diameter. In this research, Brinell hardness indentations were made using various indentation forces and ball indenter sizes. Using a confocal microscope, the indentations were measured in three dimensions from which the indentation profiles were determined. Additionally, finite element analysis (FEA) models were developed for studying the location of contact points at indentation pile-up edges. From both microscope measurements and FEA simulations, the difference between the measured indentation diameter and the actual contact diameter was determined for each indentation.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Renato R. Machado, Sérgio P. de Oliveira, Claudio A. Koch, Islei D. da Silva, Bianca da C. O. Muniz
INFLUENCE OF DIFFERENT NUMERICAL APERTURES ON HARDNESS VALUES USING AN AUTOMATIC SYSTEM OF MEASUREMENT
The objective of this work is to analyse and discuss the influence of the use of different numerical apertures (NA) and its magnification on the measurement of indentations on Vickers (HV) and Brinell (HB) hardness blocks previously certified. It was used a new reference Vickers and Brinell measurement system, recently installed and qualified at the Brazilian National Metrology Institute (Inmetro) by the National Institute of Metrological Research (iNRiM/Italy). The system used was a Galileo Galvision (LTF S.p.A., Italy) that carries out automatic measurements throughout two methods, the direct and the indirect ones. In the present work both direct and indirect methods were used. In general, the 10x lens magnification and its 0,25 numerical aperture yielded the acceptable normalized error (En) for almost all HV and HB indentation measurements done, no matter the method used. As reference values six certified blocks in three levels of hardness were studied, e.g. blocks of low, medium and high hardness values. Among them, the lowest range of Vickers hardness provided the better normalized error. The same results were obtained by analyzing the highest range of Brinell hardness, no matter the method used.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Alessandro Germak, Claudio Origlia
ANALYSIS AND ESTIMATION OF POSSIBLE LARGE SYSTEMATIC ERROR IN BRINELL HARDNESS MEASUREMENTS
Brinell hardness measurements are widely used at industrial level. For the calculation of Brinell hardness values, the measurement of the diameter of indentations is necessary. In practice, the measurement of the image created by the optical systems used for the magnification of the indentation is usually carried out. The dimension of the indentation image depends by the optical system that, in practice, transform the real indentation in image using properties of light reflection. The paper describe the effect of this influence parameter in Brinell hardness measurements in experiments carried out at hardness laboratory of Istituto Nazionale di Ricerca Metrologica (INRIM) (formerly Istituto di Metrologia “G. Colonnetti” – IMGC) with application to the data obtained at international comparison at the National Metrology Institutes level. Moreover, some methods for its evaluation and possible correction will be proposed.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Alessandro Germak, Alfonso Liguori, Claudio Origlia
EXPERIENCE IN THE METROLOGICAL CHARACTERIZATION OF PRIMARY HARDNESS STANDARD MACHINES
The Istituto Nazionale di Ricerca Metrologica (INRIM) and Galileo section of LTF S.p.a. have cooperated for many years in the field of hardness for developing and improving Primary Hardness Standards and measuring systems for their laboratories. With this experience, Galileo-LTF has realized many installations for several NMIs in the world. All these Hardness Standards and measuring systems have been metrologically characterised by INRIM. In the paper, experiences made during the metrological characterization will be shown. They include the methods and results of direct verification of influence parameters (force, displacement, time, velocity, angle, etc.) and of indirect verification (hardness scales or indenters comparison) of the systems.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Takashi Yamamoto, Kensuke Miyahara
DEFINITION OF NEW INDUSTRIAL HARDNESS TEST USING EQUIVALENT INDENTATION DEPTH
The Rockwell hardness test is commonly used and accepted by many industrial users, but the hardness value requires conversion between scales because the geometry of the indenters and the load ranges are different. On the other hand, hardness calculation using pyramidal indenters is quite simple and can be applied to any load range, though it is much more complicated to calibrate the frame compliance and the truncation of indenters in nanoindentation measurement. For this reason, nanoindentation measurement is not yet fully industrially friendly. In order to improve the above situation, newly developed industrial hardness test methods and a new concept of “Equivalent indentation depth (or indentation depth index)” were proposed and investigated in this paper. These methods are based on the principle of “similarity” of Vickers and other pyramidal indenters, and take advantage of the industrial and practical usability of the Rockwell hardness test. Experimental results that covered macroscopic through nanoscopic ranges show that the methods can be applied to a wide range of test loads. One of the expected advantages of the methods of performing nanoindentation and other instrumented indentation tests (ISO 14577) is that the hardness is not significantly influenced by the frame compliance or the truncation of indenters. Other advantages over conventional hardness tests are also discussed in this paper. More experimental work is necessary to confirm and establish the new methods.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

John Song, Sam Low and Li Ma
TOLERANCING FORM DEVIATIONS FOR NIST STANDARD REFERENCE MATERIAL (SRM) 2809 ROCKWELL DIAMOND INDENTERS
The National Institute of Standards and Technology (NIST) is developing Standard Reference Material (SRM) 2809 Rockwell Diamond Indenter to support Rockwell hardness standardization. Most tolerances of the SRM indenters are adopted from those of the calibration grade Rockwell indenters specified in ASTM and ISO standards except the form deviations from tip radius. Based on the historical data of geometrical measurements and hardness tests at NIST, and the results of FEA (Finite Element Analyses) simulations, a tight tolerance, ± 0.5 µm, is specified for the form deviations of the SRM indenters.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

O Kruger, L Mostert
THE USE OF A µCMM IN THE CALIBRATION OF HARDNESS INDENTERS
In order to perform traceable hardness measurements using Rockwell Hardness Indenters, the indenter must conform to the requirement of ISO 6508-3 standard. The standard defines specifications for the geometric parameters for this type of indenter. Conformance to this standard is of particular importance to all calibration laboratories which operate in accordance with ISO/IEC 17025. At present there is no facility in South Africa with the capability of calibrating indenters for conformance to ISO 6508-3. This situation is being addressed through a series of studies currently being conducted at the National Metrology Institute of South Africa. The following parameters are calibrated using the µCMM. ISO 6508-3 specifies a radius of 200 µm with an uncertainty of ± 5 µm for Rockwell Hardness Indenter tips. Also specified in the ISO standard is the cone perpendicularity between the axis of the diamond cone to the axis of the indenter holder, with a specification of ± 0,03°. The last part of the ISO standard which was investigated states: “The surface of the cone and the spherical tip shall blend in a truly tangential manner.” All these parameters were measured and associated uncertainties calculated to prove conformance with ISO 6508-3 for the calibration of hardness indenters.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

D. Schwenk, K. Herrmann, G. Aggag, F. Menelao
INVESTIGATION OF A GROUP STANDARD OF ROCKWELL DIAMOND INDENTERS
The specific hardness deviations of a Rockwell diamond indenter can be determined by a group standard, consisting of several indenters, using correction functions. In this paper the establishment of an HRC group standard in the PTB and comparative investigations of the group standards in the PTB and the calibration laboratory MPA NRW in Germany are reported. Above all the group standard is advantageous for maintaining the stability of the Rockwell hardness scales.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

A. Štibler, K. Herrmann
INDIRECT VERIFICATION OF ELASTOMER HARDNESS TESTERS USING HARDNESS REFERENCE BLOCKS
Hardness measurement methods for rubber and plastics are described in the standards ISO 7619-1, ISO 7619- 2, ISO 868 and ISO 48. Rising requirements for the accuracy of this hardness measurement have led to the result that the users of rubber hardness testers and also metrology experts who deal with their calibration need a calibration method to check the overall function of the testers acknowledged by a standard. Therefore extensive experiments were conducted in a cooperation between the Physikalisch - Technische Bundesanstalt (PTB) in Braunschweig (Germany) and the ZAG Ljubljana (Slovenia). The results have been used as a basis for the elaboration of the relevant international standard ISO 18898 which was published in 2006. In this standard direct verification methods are laid down. An indirect verification method using rubber hardness reference blocks, which is also applicable for the verification of hardness testers, is presented in this paper. At present hardness reference blocks are available only for some of the hardness scales which are used for rubber materials. Suchwise, Shore A, IRHD N and IRHD M reference blocks are available in the market. During the verification process the hardness tester is calibrated by using rubber hardness reference blocks. The evaluation of the repeatability and the error of the hardness testers including the uncertainty of measurement of the calibration results is given in this paper.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Li Heping and Zhou Xing
THE APPLICATION AND EFFECTS OF THIN SHEET HARDNESS REFERENCE MATERIALS WITHOUT AGING EFFECT
Hardness test methods are widely used in mechanical properties test area. While reference materials are essential important tools to control test accuracy or uncertainty. According to current test method standards, the thickness of hardness reference materials must be not less than 6 mm for Rockwell hardness or not less than 5 mm for Vickers hardness. To measure thinner sample which is commonly used in industry, and to guarantee the test results, a thin sheet reference sample is demanded.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Vytautas Vasauskas, Juozas Padgurskas, Raimundas Rukuiza
THE MICRO-HARDNESS ANISOTROPY OF FLUOR-OLIGOMERIC AND Fe-Co-W COATINGS
The influences of indenter micro-geometry on the micro-hardness performance in the film/substrate system are discussed. Experimental results verify the force required to produce hardness indents for thin films, the measurement of the size of plastic zone cross-sections of the indents, and the characterisation of the indenters. It was found that the deformation is highly localised beneath the indenter and failures in the corners of pyramidal indenters occurred.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Shigeo Sato, Masayuki Sato
HARDNESS MEASUREMENT OF COATING THIN FILM BY INDENTATION PROFILE OBSERVATION USING SCANNING PROBE MICROSCOPY
According to the principle of a conventional Vickers (Berkovich) hardness measurement, hardness is calculated from diagonal lengths or side lengths of indentation. The diagonal length, the conjunction line length of pyramidal indentation, and the distance from the vertex to the base of trigonal pyramidal indentation are measured accurately by observing a vertical cross section. Scanning probe microscopy (SPM) is a good method for observing the vertical and horizontal cross sections of the indentation. However, such parameters in the cross section profile must be defined as the principle of the method to obtain a reliable nano-hardness value.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Yutaka Seino
ANALYSIS OF INDENTATION DEPTH DEPENDENCE OF ELASTIC PROPERTIES OF INTER-LAYER DIELECTRIC FILMS ON SILICON
Analysis of indentation depth dependence of elastic modulus of soft films on silicon substrate measured by nanoindentation was studied. The experimental results were compared with two existing models that describe the effects of the substrate on elastic modulus of layered solid. Saha-Nix model that is the recent modification of King model agreed well with the experimental results to a certain limit of the indentation depth. It was found that the depth limit which Saha-Nix model is valid depended almost linearly on the relative elastic modulus of the film to the substrate Ef/Es. We further introduced an additional scaling parameter that is a linear function of Ef/Es in Saha-Nix model. The improved model was applied to porous silica low-k films. The model predicted a constant intrinsic elastic modulus of the film up to a depth of 30 % of the film thickness.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Masayuki Fujitsuka, Makoto Yamaguchi, Shigeru Ueno, Genichiro Kamiyama, Shigeo Katayama
MEASUREMENT OF A RESIDUAL IMPRESSION BY THE LASER SCANNING MICROSCOPE WITH DIC UNIT
When the nanoindentation testing is carried out, it is very important to understand the residual impression and the surface around it. Generally Atomic Force Microscopy (AFM) is used to obtain them. However, it is necessary to understand correct shape in the point of cantilever in AFM procedure. And, measuring them by AFM procedure precisely, very long measurement time and very clean environment and so on are needed. So, there are many difficulties to use AFM procedure for measuring residual impression and the surface around it. On the other hand, there are some procedures to measure them. Scanning Electro Microscopy (SEM) is effective to the grasp of the shape of the surface and the ruggedness. But, this procedure needs the coating of the sample and the vacuum atmosphere. Therefore it is not a simple and quick procedure. In this paper, authors used the laser scanning microscope with a differential interference contrast unit to obtain the data of a residual impression and the surface around it. This procedure is the very simple and quick procedure in no contact and measuring in various environmental conditions. The data of indentation depth from this procedure is obtained at the nano-meter order. The results from this procedure compare with the results from displacement of nanoindentation test.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Satoshi Takagi, Christian Ullner
CRITICAL CHECK OF THE REPEATABLITY AND BIAS OF HARDNESS TESTING MACHINES RESTRICTED BY THE HARDNESS STANDARDS
Since the ISO standards for four major hardness scales were revised in 2005, the indirect verification has been considered as the mainstream of the traceability chain of hardness. In the recommended procedure of ISO, the uncertainty of hardness machine should be estimated and added to the combined uncertainty of hardness measurement value. The equation to calculate this uncertainty component was introduced according to the rectangular distribution of bias of hardness machines. However, if the error propagation is investigated in detail, the uncertainty of hardness machines should be obtained by considering the probability distributions of the uniformity of hardness reference block, the repeatability and the bias of hardness machine. In addition, the distribution of verification results should be calculated after some hardness machines are screened out by the maximum permissible values requested in ISO. In this paper, the probability distribution of the hardness machines, which passed in the indirect verification, are obtained by means of the Monte Carlo method. Since a calibration value of hardness is obtained only by measuring a specimen, it is not possible to separate the uncertainties of hardness machine and hardness block. Then the result of indirect verification is affected by the uniformity of reference block. The relation between the distribution of passed hardness machines and the uniformity of reference blocks is presented for several hardness scales. In addition, the guideline to estimate the uncertainty of the measured hardness values can be verified by means of the Monte Carlo method.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Joachim Frühauf, Eva Gärtner, Konrad Herrmann, Febo Menelao, Dieter Schwenk, Thomas Chudoba, Hans-Peter Vollmar
CALIBRATION OF INSTRUMENTS FOR HARDNESS TESTING BY USE OF A STANDARD
As a standard for the calibration of force and depth scales of hardness testing instruments a system of silicon springs is described. The standard shows a linear force-deflection characteristic F = k · f up to a stop point (typical: Fst = 420 mN; fst = 22 µm). For the calibration of stiffness and stop point of the standard the characteristic should be measured using a spherical indenter. In view of the practical application for the assessment of instruments also Vickers indenters can be used. In this case indentations are produced. The resulting wear can be minimized by reducing the maximum force and using only the measured stiffness k for a quick assessment.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Hiroshi Yamamoto , Takashi Yamamoto
DEVELOPMENT OF HIGH-ACCURACY HARDNESS STANDARD BLOCKS IN JAPAN AND FUTURE OUTLOOK
The sources of problems with a hardness testing machine that are detectable via day-to-day inspection using hardness standard blocks, or indirect verification, can be roughly divided into three: the indenter, the test force, and the indentation measuring apparatus. If any problems are detected, repair or recalibration of the testing machine, focusing on the aforementioned three factors, is carried out based on the results of verifying the direct accuracies of that machine. These efforts have been accumulated to acquire the high level of hardness testing technology as is available now. This article describes the development of a hardness standard block as a tool for indirect verification of hardness testing machines, discusses possible factors that have effects on hardness measurements, and provides insights into the future hardness tests from a perspective of a hardness block manufacturer.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

Takashi Usuda, Hajime Ishida, Yutaka Seino, Satoshi Takagi, Koichiro Hattori, Hidetaka Imai
CALIBRATION AND MEASUREMENT CAPABILITY MONITORING PROCESS UNDER APMP ACTIVITIES
With reference to CIPM-MRA (Mutual recognition of national measurement standards and of calibration and measurement certificates issued by national metrology institutes), APMP (Asia Pacific Metrology Programme) have established 11 TCs (Technical Committees) including TCM (Technical Committee of Mass related quantities) which discusses hardness related issues in APMP. Under the TC activities, the guidelines and procedures for accepting CMCs (Calibration and Measurement Capabilities) and QS (Quality System) have been drawn up by taking closer cooperation with the JCRB (Joint Committee of the RMOs and the BIPM). Therefore, the concept of the procedures and guidelines are effectively introduced in the course of intra-regional and inter-regional reviews for submitted CMCs within APMP and from other RMOs (Regional Metrology Organizations), respectively.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

G.W. Bahng, N.H. Tak, J.Y. Song and J.H. Hahn
TEST CYCLE CALIBRATION SYSTEM FOR ROCKWELL HARDNESS TESTER
The direct verification of Rockwell testing machines comprises four parts such as test force, indenter, depth measuring device, and testing cycle as seen in ISO 6508-2. Among them, the verification of testing cycle is generally carried out by using a stopwatch on industrial sites, which is not so reliable. In addition to this, most of commercial hardness testing machines produced nowadays are automatically controlled by the embedded software, which makes it much more difficult to calibrate the testing cycle. It implies that even though hardness testing machines are advanced more, the calibration of the testing cycle does not keep up with their advancement. To overcome this problem, an on-site calibration system was developed to calibrate the testing cycle of both the automatically controlled as well as manually controlled Rockwell hardness testing machines. The calibration system is composed of load cell, indentation depth measuring apparatus and embedded clock. Using this system, measurement of test force, application velocity of test force, and indentation depth are possible simultaneously in real time, which enhances the efficiency and reliability of calibration procedure.
HARDMEKO 2007, Tsukuba, JAPAN, 2007

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