IMEKO Event Proceedings

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V. Vasauskas
DYNAMIC HARDNESS DURING DIFFERENT PHASES OF INDENTATION
The paper reports on the underlying concept for securing the measuring basis used in the method of dynamic hardness which employes one of the standard indentation methods and various shapes of indenter. The complete dynamic indentation cycle can be divided into the three following phases: starting phase, indentation phase and rebound phase. The value for several engineering metals obtained dynamic hardness in various phases of indentation was 1.12 – 1.40 higher than the static hardness.
11th Conference on Hardness Measurement, Celle, Germany, 2002

H. Yamamoto, T. Yamamoto, H. Kawashima, S. Sudoh
HARDNESS TRACEABILITY SYSTEM
As a matter of fact, global standards for hardness testing are set by International Organization for Standardization. The ISO standard for hardness testing consists of three parts: Part 1 is for test methods, Part 2 is for testing machines, and Part 3 is for hardness standard blocks. JIS provides three independent standards, but they have perfect consistency with the three parts of the ISO hardness-testing standard. These standards prescribe that hardness testing machines first be subject to direct verification of their test force, indenter, testing cycle, and hardness indicator, and then that hardness must actually be measured using standardized blocks for indirect verification. This is a globally agreed fact. In this connection, the traceability or the uncertainty of Rockwell hardness has been a topic of international debate. This paper discusses our position on this issue as a manufacturer of hardness standardized blocks.
11th Conference on Hardness Measurement, Celle, Germany, 2002

D. Schwenk
VARIATION OF THE CALIBRATING VALUE AND THE RANGE DEPENDING ON THE NUMBER OF THE CALIBRATING INDENTATIONS DURING THE ROCKWELL HARDNESS TEST
Represented is the problem at the definition of measure values in the standards from the statistical point of view. The definition of the calibrating of hardness reference blocks in the standards will be translated to a statistical model formulations. The statistical model will be checked by experimental measurements. The problem of the determination of a quality feature for the hardness reference blocks will be discussed.
11th Conference on Hardness Measurement, Celle, Germany, 2002

R. Affri, G. Barbato, S. Desogus, A. Germak, C. Origilia, D. Perteghella
METROLOGICAL CHARACTERIZATION OF OPTICAL MEASURING SYSTEM FOR HARDNESS INDENTERS
The verification of the geometry of Rockwell indenters has been widely studied in the past and, at the present, it is one of the most important tasks (in the uncertainty budget of hardness measurements) in discussion in many international organizations involved in the hardness field. The new measuring system designed in IMGC and developed in cooperation with AFFRI has been characterized and the results of the calibration are presented. The uncertainty evaluation has been calculated following the ISO guide on uncertainty evaluation. At the end, the results of the intercomparison between the new instrument and the instrument used up to now in IMGC laboratory, completely different from the point of view of measurement methodology, are presented.
11th Conference on Hardness Measurement, Celle, Germany, 2002

A. Stibler, K. Herrmann, Th. Polzin, A. Germak
COMPARISON MEASUREMENTS OF HARDNESS SCALES FOR ESTABLISHING THE HARDNESS STANDARD OF SLOVENIA
A commercial hardness testing machine was provided to represent a hardness reference standard in Slovenia. In order to evaluate how accurate the hardness scales realised with this machine could be, the main influence factors contributing to the uncertainties were verified and comparative measurements carried out, the results of which were compared with several laboratories owning primary hardness standard machines.
11th Conference on Hardness Measurement, Celle, Germany, 2002

A. Wehrstedt
SITUATION OF STANDARDIZATION IN THE FIELD OF MECHANICAL TESTING AND MEASUREMENTS
Standardized mechanical test methods are referred in many materials and product standards for the characterization of quality of the materials or products. Mechanical testing is carried out on materials for three different reasons: - For quality control purposes to ensure that a material conforms to a technical specification or that it has been correctly processed. - To provide information which can be used in the design of a component or structure. - As part of investigations into the reasons for failures in service. Hence the results achieved from the mechanical testing of products that are made of / or from materials are used to help guarantee the safety and reliability of materials which in turn ensures the safety of those products. The paper gives an overview on the standardization activities of the last ten years for the different fields of mechanical testing as uniaxial, ductility, hardness, toughness and fatigue testing .
11th Conference on Hardness Measurement, Celle, Germany, 2002

N. Huber, E. Tioulioukovsski
SMART INDENTATION METHODS: THE APPLICATION OF NEURAL NETWORKS
In the last decade, the nanoindentation technique has become one of the most important characterization methods in micro dimensions. The experimental and analytical techniques have been pushed towards an identification method that can compete with tensile tests. It is self-evident to apply these powerful tools in macro dimensions as well, where the nanoindentation technique has its roots. In this paper a new method is presented how the true stress-strain curve as well as the viscosity and creep behaviour of a given material can be extracted from the indentation curve by using a smart analysis tool based on neural networks. Finite Element simulations are carried out for randomly chosen sets of material parameters and maximum indentation depth. The resulting load-depth and depth-time curves are collected in a database together with the material parameters. With this database neural networks are trained to identify the material parameters from measured load-depth and depth-time curves.
11th Conference on Hardness Measurement, Celle, Germany, 2002

F. Loeffler (F. Löffler), A. Sawla, P. Strobel
CALIBRATION OF THE DEPTH-MEASURING DEVICE OF ROCKWELL HARDNESS TESTING MACHINES
In addition to the indirect verification using reference blocks and a reference indenter, it is possible to realise the calibration by direct verification of the test force, the indenter, the depth-measuring device and the testing cycle. Some conditions of the calibration process, e.g. the verification range, and the necessary accuracy of the depth-measuring device are described in standard ISO 6508-2. With reference to these parameters, a new depthmeasuring calibration device was developed. The study describes the function of this device and the calibration process. The advantages of this new process are that the measurement takes place in the axis of force application and that the calibration is independent of the Rockwell hardness scales. During calibration, the force stresses the calibration device but not the sensitive measuring sensor. Results of a real depth-measuring device verification are also presented.tion process. The advantages of this new process are that the measurement takes place in the axis of force application and that the calibration is independent of the Rockwell hardness scales. During calibration, the force stresses the calibration device but not the sensitive measuring sensor. Results of a real depth-measuring device verification are also presented.
11th Conference on Hardness Measurement, Celle, Germany, 2002

M. Griepentrog, Ch. Ullner, A. Dueck (A. Dück)
INSTRUMENTED INDENTATION TEST FOR HARDNESS AND MATERIALS PARAMETER FROM MILLINEWTONS TO KILONEWTONS
The ISO/DIS 14577 Metallic materials - Instrumented indentation test for hardness and materials parameters – Part 1-3 (IIT) concerns test forces up to 30 kN. The paper reports on IIT at test forces ranging from 0.002 N to 1000 N on non – magnetizable steel X8 CrMnN 18- 18 (1.386) with well polished surface using Vickers indenter and four hardness machines of different design (Nano Indenter XP, Fischerscope H 100, Zwick Z005 with Universal hardness head and a laboratory four-column set up materials testing machine) according to the standard. Using mostly identical test parameters the results of the different machines are almost in good agreement. Estimated small differences are caused by the different uncertainties of the used machines and by different methods of mathematical analysis of the detected raw data.
11th Conference on Hardness Measurement, Celle, Germany, 2002

Ch. Ullner, Th. Reich
STUDY ON THE CAPABILITY OF MATERIALS AS REFERENCE BLOCKS FOR THE MACRO RANGE OF INSTRUMENTED INDENTATION TEST
Part 3 of the ISO 14577 “Instrumented indentation test for hardness and materials parameters“ (IIT) concerns the calibration of reference blocks. Besides the widely spread activities for supplying reference blocks in the nano and micro range it is needed to be taken into account the macro range too. The paper reports on test results on ceramic materials which are tailored for reference blocks. The specimens made of Si3N4, SiC, or Al2O3 ceramics are highly homogenous and exhibit an increased quality with a roughness Ra ≤ 0.005 µm. They are successfully used for reference blocks of the traditional Vickers and Knoop hardness. In comparison, the capability of hardened steel which is used for traditional hardness techniques is studied.
11th Conference on Hardness Measurement, Celle, Germany, 2002

Th. Choudoba, M. Griepentrog, U. Beck
COMPARISON BETWEEN VICKERS HARDNESS AND INDENTATION HARDNESS
The Vickers hardness is an often used hardness definition, mainly in the force range above 0.5 N. With decreasing film thickness and the need of lower loads, depth and force sensing measurement techniques became more and more important and a new indentation hardness was introduced, finally resulting in the international standard ISO 14577. Therefore investigations regarding the comparability of both hardness definitions are of high interest. In principle it should be possible to obtain the same hardness number with both measurement methods if the true contact area can be determined. The agreement is checked for a large selection of materials and instruments for a force of 0.5 N (HV0.051). The calculation of the correct contact area from depth sensing measurements is also checked by a comparison of the indentation modulus with the Young’s modulus, obtained with other methods.
11th Conference on Hardness Measurement, Celle, Germany, 2002

A. Liguori, A. Germak, G. Gori, E. Messina
GALINDENT: THE REFERENCE METROLOGICAL SYSTEMS FOR THE VERIFICATION OF THE GEOMETRICAL CHARACTERISTICS OF ROCKWELL AND VICKERS DIAMOND INDENTERS
The paper describes the GALINDENT system that LTF – Galileo Hardness Testing Department, in co-operation with the Institute of Metrology "G. Colonnetti", has developed for the geometrical verification of Rockwell, Vickers diamond indenters, as prescribed by ISO Standards. This system consists of two instruments: an Interferometric Sine-Bar, for angular, straightness and flatness measures and a Rotary Table, for the verification of the spherical tip of Rockwell indenters. These two devices can be set up in one workstation, interfaced with the same computer for data analysis. A software package has been specifically developed to manage the entire system. The measurement test cycle is completely automated in order to ensure objective and reliable results. The operator interface, based on a graphic window menu in the Windows® environment, is extremely user friendly and it does not require any programming knowledge.
11th Conference on Hardness Measurement, Celle, Germany, 2002

G. Barbato, G. Brondino, M. Galetto, G. Vicario
'ZERO POINT' IN THE EVALUATION OF MARTENS HARDNESS UNCERTAINTY
The Instrumented Indentation Test is based on simultaneous recording of force and indentation depth, obtained during test cycle. The force-depth curve, describing the indentation pattern, is typically formed by two parts having the “zero-point” in common, i.e. the first contact point between the indenter and the surface of test piece. The zero-point determination is a crucial aspect for Martens Hardness evaluation, so that relevant ISO standard suggests to estimate it by extrapolation of polynomial fitted functions. In this paper a new model, based on a segmented function, is proposed. This approach implies the use of maximum likelihood estimator for parameters determination. The corresponding uncertainty is provided through the covariance matrix of the regression model.
11th Conference on Hardness Measurement, Celle, Germany, 2002

S.R. Low
AN EMPIRICAL APPROACH TO DETERMINING ROCKWELL HARDNESS MEASUREMENT UNCERTAINTY
Characteristics of the empirically developed Rockwell hardness test make it difficult to determine measurement uncertainty using methods based on mathematical models describing the relationship between the measurand and the influence quantities. An empirical approach to determining Rockwell hardness uncertainty has been developed, which provides a method based on the familiar procedures and practices of Rockwell hardness testing laboratories. The approach views the hardness machine and indenter as a single measuring device, and considers uncertainties associated with the machine repeatability and the usage of the machine over time with varying environmental conditions and with different operators. The approach also considers the measurement bias of the Rockwell hardness machine as compared to reference standards.
11th Conference on Hardness Measurement, Celle, Germany, 2002

A.C. Vidal, A.R. Martins, I.M.V. Caminha, A. da Cunha Rocha, S.P. Oliveira
THE INFLUENCE OF THICKNESS ON THE NON UNIFORMITY VALUES OF ROCKWELL B HARDNESS STANDARD BLOCKS
In the present work, the influence of thickness variation and of the microstructural aspects on the hardness uniformity of Rockwell B standard blocks is discussed. In order to correlate the results, two different heat treatments were performed on the steel employed to manufacture the standard blocks. Three different thickness ranges were studied for each of the two heat treatments conditions applied to the standard blocks material. The microstructural characteristics were studied by means of optical microscopy. The hardness measurements were carried out in hardness testing machines belonging to the three Brazilian Institutes involved in the present study. The results indicate that the non-uniformity hardness values are directly affected by the resulting microstructural changes due to the applied heat treatments. However, a relationship between thickness variation and hardness values has not yet been entirely understood.
11th Conference on Hardness Measurement, Celle, Germany, 2002

J. Song, S. Low, L. Ma
TOLERANCING FORM DEVIATIONS FOR ROCKWELL DIAMOND INDENTERS
The form deviations of Rockwell diamond indenters can cause significant differences in Rockwell hardness readings. In order to control that effect, tolerances for form error deviations of Rockwell diamond indenters have been specified in both the American Society of Testing and Materials (ASTM) and the International Organization for Standardization (ISO) standards. In this paper, experimental data on the effects of form deviations of Rockwell indenters are analyzed. Finite Element Analysis (FEA) is used to simulate the effect of form deviations on HRC readings. Theoretical analyses are verified by experimental results. Based on these results, as manufacturing and measurement techniques for Rockwell diamond indenters improve, it is suggested that a tighter tolerance be specified for the form deviations of Rockwell indenters used for calibrations of reference blocks.
11th Conference on Hardness Measurement, Celle, Germany, 2002

M. Tsujii, F. Koshimizu, E. Furuta, K. Kojima, H. Hayashi, H. Ishida
DEVELOPMENT AND PERFORMANCE OF HARDNESS TESTING MACHINE CALIBRATION PROCESSOR
The calibration device capable of performing direct verification of both test force & indentation depth, which are fundamental elements of a Rockwell type hardness tester, was developed. This device can also carry out verification of operating conditions. In this paper, the examples of uncertainty of hardness calculated, based on uncertainty of each element, using this device are shown and the calibration results on the conventional testing machine calibrated by the standardized Rockwell hardness testing machine, which has been used at Akashi Corp., are also shown.
11th Conference on Hardness Measurement, Celle, Germany, 2002

K. Hattori, S. Takagi, Y. Seino, H. Nakano
DISPLACEMENT MEASUREMENT OF AN INDENTATION TESTER USING HETERODYNE INTERFEROMETER
We have developed an heterodyne laser interferometer system to measure the indenter displacement of instrumented indentation at nano-/micro- ranges. The developed interferometer was applied to measure the displacement of an commercial type indentation tester. The interferometer system and the tester was set on the different anti-vibration systems. So the main difficulty of this measurement was how to got rid of the relative vibration effect. We designed the system as that the reference points of the system is set to the displacement measurement mirrors on the testers. The total stability of the displacement measurement system was about 10 nm in spite of the larger amplitude of the relative vibration, which is larger than the 1 mm. We can successfully measure the indenter displacement by using newly designed interferometer system and is compared the displacement signal obtained from the tester.
11th Conference on Hardness Measurement, Celle, Germany, 2002

S. Tagaki, K. Hattori, Y. Seino, H. Nakano
ESTIMATION OF EFFECTS OF INDENTER-TIP GEOMETRY BY MEANS OF FINITE ELEMENT ANALYSIS OF NANO-INDENTATION
To investigate the influence of geometric error of indenter tip in nano-indentation test, direct measurement of indenters and analyses of indentation process are carried out. Geometry of indenter tip is measured with a scanning probe microscope and geometrical parameters such as face angles, tip radius and truncation length are calculated. Based on these results, the models for the finite element analyses are created. Analyses of indentation processes into a metal sample are carried out and the influence of tip geometry is discussed.
11th Conference on Hardness Measurement, Celle, Germany, 2002

P. Neumaier, G. Michalzik
MECHANICAL CHARACTERIZATION OF MATERIAL COATINGS USING THE FISCHERSCOPE H100 (R) COMPACT
The load/indentation depth method has received broad acceptance both in quality control and in research and product development for characterizing the mechanical behavior of thin coatings and also of small and smallest material areas. Continuous high-resolution recording of test load and indentation depth for the full test cycle (loading and unloading) is used in a variety of ways in particular for test loads in the microhardness range. Contributing factors to its acceptance were the greater information content of the measurement results, the operator-independent test procedure and the speedy standardization of the test method. However, until now, the use of the instrumented indentation test has been limited to relatively small specimens or required the supply of small samples. Extracting a sample leads to the destruction of the product, and the separate production of a sample requires additional expenditures and does not always ensure comparable properties. The computer-controlled Fischerscope® H100 Compakt (H100 C) opens entirely new areas of applications for efficient tests of materials and thin coatings both on small samples/micro components and on large specimens such as coated shafts, forming components, etc. Using selected examples, this paper reports about the capabilities of this new measurement technology for applications with small test loads and indentation depths as well as the use of the mobile measuring head H100SMC on large-area and compact specimens.
11th Conference on Hardness Measurement, Celle, Germany, 2002

J.L. Nascimento, F.S. Pires, A.C. Rocha, I.M.V. Caminha
THE INFLUENCE OF MICROSTRUCTURE HOMOGENEITY ON THE UNIFORMITY OF HARDNESS STANDARD BLOCKS
The aim of this work is to correlate the homogeneity of the microstructure of two certified hardness standard blocks, both with the same hardness value range, with its uniformity hardness values. In order to identify the morphological characteristics of the blocks studied, as grain size distribution, an automatic image analysis system with software based on ASTM E112 and ASTM E1382 standards was employed. The hardness measurements were carried out in industrial hardness tester machine, in three different regions of the blocks. The results obtained for both blocks showed that, for the regions where coarsed grains were observed as islands of microstructure non-homogeneity, the hardness values dropped compared with those mentioned in the calibration certificates. The microstructure homogeneity plays therefore an important role on the uniformity of hardness values for reference blocks.
11th Conference on Hardness Measurement, Celle, Germany, 2002

L. Ma, S. Low, J. Song
COMPARISON OF ROCKWELL B HARDNESS (HRB) TESTS USING STEEL AND TUNGSTEN CARBIDE BALL INDENTERS
Significant measurement differences occur in Rockwell B hardness (HRB) tests when using 1.588 mm diameter ball indenters made of steel and tungsten carbide (WC). In this paper, finite element analysis (FEA) is used to simulate the HRB indentation process using steel, tungsten carbide and rigid ball indenters on the same tested materials under the same testing conditions. The influence of the deformable indenters (made of steel and WC) on the HRB indentation is assessed by comparing their FEA results with those of a non-deformable rigid indenter. The deformations of both the indenters and tested materials during the loading and unloading period are analyzed. The effect of deformable ball indenters on HRB hardness measurement values is discussed and further verified by experiments.
11th Conference on Hardness Measurement, Celle, Germany, 2002

R. Barbato, R. Boi, R. Ragazzini
DETERMINATION OF MICRO-INDENTATION HARDNESS OF ORGANIC COATINGS
Many industrial products have to be coated by organic materials not only for aesthetical reasons, but specially to prevent the integrity of the metallic substrate from corrosion attacks during their service life; then, the corrosion resistance of metallic component is often assigned to the physical properties of the coating material. A lot of specific tests are available in the field of surface treatment characterization, in order to assess mechanical, physical and durability properties of paints and varnishes. Among them, indentation hardness allows to investigate on the local properties of a painted layer, not only on the external surface but also into the coating thickness, making it possible to verify hardness at every depth of the layer; non-uniformity in hardness values can be referred to the painting process (curing conditions, coating material, etc.). Hardness measurement technique on the transversal section required particular attention in the specimen preparation; hardness tests were performed by using a Knoop indenter, according to the standard ISO 6441-1. In the present paper are reported the results of several hardness tests performed on the surface and on the transversal section of various aluminium painted samples, some of them partially polymerized to different degrees. The same results have been compared with the results of commonly used tests for coating characterization, as: Taber abrasion test, hardness pencils test, Buchholz indentation test and also impact test.
11th Conference on Hardness Measurement, Celle, Germany, 2002

K. Herrmann, A. Germak, F. Menelao, G. Barbato, G. Brondino
INDENTATION VELOCITY EFFECT ON MARTENS HARDNESS MEASUREMENT
The Martens Hardness (HM) is an important parameter characterising the elasticplastic properties of the to be investigated sample material which is derived from the instrumented indentation test. At present the standardisation of the instrumented indentation test in the framework of ISO/DIS 14577-1, -2, -3 is underway. This standard addresses the macro-, micro- and nanorange of the indentation test. The peculiarities of the nanoindentation test when measuring samples with thin coatings (coating thickness d < 2 µm) will be considered in ISO/CD 14577-4 for which inputs came from CEN TC 184/WG 5 and from the EU-project „INDICOAT“. Martens Hardness presents a number of advantages, but, as any newly defined method, requires a general analysis of influence quantities to determine the sensitivity coefficients necessary for the uncertainty evaluation. Indentation velocity was found to be one of the main influence quantities for Rockwell and Vickers scales, therefore its effect was evaluated in a previous work that indicated an effect much higher than expected. In that work some warning was given, because the analysis was based on the results obtained on a single Hardness Standard Machine, moreover based on a simple experimental plan that did not guarantee any separation of the effects of time and velocities. In the present work these drawbacks are overcome. The analysis is based on an experimental plan that takes into account the load increasing time, the velocity of the initial part of indentation and the velocity of the last part of indentation, that is for the Rockwell and the Vickers method the most important influence factor. Moreover, following the resolution adopted within the recent ISO TC 164/SC3 meeting during which Martens Hardness was extended to cover from nano to macro ranges, experiments are performed on each of these ranges and with different machines, delivering in that way more significant results.
11th Conference on Hardness Measurement, Celle, Germany, 2002

Th. Polzin, D. Schwenk
EXPERIENCES WITH THE DETERMINATION OF UNCERTAINTY BRINELL HARDNESS, PC PROGRAM
After the next revision of the Standards for hardness testing, a determination of uncertainty has to be. part of the Standards. In the following text two methods for the determination, proposed for the ISO Standards of hardness, are described and the implementation of both methods in an Excel-based file is explained.
11th Conference on Hardness Measurement, Celle, Germany, 2002

Th. Polzin, D. Schwenk
WORLD-WIDE UNIFIED SCALES FOR THE ROCKWELL HARDNESS TEST WITH CONICAL INDENTERS
The aim of this round robin test was to discover what needs to be done to achieve the worldwide unification of Rockwell hardness scales using diamond indenters (HRC, HRA, HRD, HR15N, HR30N and HR45N). These scales are the most commonly used and their unification is of high industrial importance. The current degree of unification at an international level was assessed by conducting a round robin test. Seventy four specially developed hardness test blocks were all calibrated by twelve laboratories in eleven countries and the results were compared. Test parameters were specified that were more precise than those required by the standards. The indenters used to make hardness measurements have a significant effect on the measured result. To separate these indenter effects, measurements were made using common indenters as well as the indenters normally used by the laboratories.
11th Conference on Hardness Measurement, Celle, Germany, 2002

M. Tietze, M. Kompatscher
PREDICATIVE HARDNESS TESTING FOR PRODUCTION CONTROL AND MATERIALS DESIGN
In-situ high-temperature rebound hardness testing according to the EQUOTIP® principle is useful to study effects of secondary hardening on strength and thermal stability, e.g., of highly alloyed tool steels. In-line material characterization and in-production testing are now feasible and offer new possibilities for production control and materials design.
11th Conference on Hardness Measurement, Celle, Germany, 2002

M. Fujitsuka, T. Ishibashi, S. Sukigara, H. Amano, M. Ohki
STUDY ON EVALUATION METHOD OF DETERMINING YOUNG'S MODULUS USING ULTRAMICRO HARDNESS TESTER WITH A SMALL BALL INDENTER
The aim of this study is to determine Young’s modulus by means of measured indentation load, depth and elastic recovery displacement of an indenter during loading and unloading processes using a developed horizontal ultramicro hardness tester. In order to determine correctly Young’s modulus of materials in narrower and shallower area of nanometer or micrometer level, authors use very small ball indenters that are made by bearing ball of a diameter in 0.3 mm and 0.5 mm. Several metal specimens [carbon steel, stainless steel, high tension brass and aluminum alloy] are used in test. Young’s moduli of metal specimens calculated on the ball indentation theory show good agreements with that of uniaxial compression test. As a result, effectiveness of evaluation method of determining Young’s modulus with a small ball indenter is confirmed.
11th Conference on Hardness Measurement, Celle, Germany, 2002

E. Reimann
MARTENS HARDNESS - MORE THAN JUST HARDNESS TESTING
Exemplary results of the instrumented indentation test within the macro region are presented to provide an insight into the potential of the Martens hardness test method and to deliver new knowledge. Measurements on reference test blocks are carried out using a Zwick hardness testing machine, which is equipped with digital measurement and control technology. Representative results show, for instance, the influences of test force, as is well-known from Vickers hardness, and of test parameters on the result gained. An overview describes the manifold uses of the hardness measurement head of Zwick, in R & D and in industrial applications.
11th Conference on Hardness Measurement, Celle, Germany, 2002

P. Grau, H.S. Leipner, D. Lorenz, A. Zeckzer
TRENDS IN THE DEVELOPMENT AND APPLICATION OF THE NANOINDENTATION METHOD
One of the most important trends now is the application of nanoindentation for fundamental investigations of elementary mechanisms of mechanical deformation under very high pressure in the local contacted region. Representative examples are given. We have studied in detail the homogeneous generation of dislocations at room-temperature by nanoindentation in locally dislocations-free monocrystals. The discontinuity of load-penetration depth-curve referred to as Pop-in-effect is the result of the nucleation of the first dislocation loops and subsequent drastic plasticity response of the material by indentation due to multiplication processes. The mechanical stresses responsible for this process were calculated in the framework of elastic contact theory (Hertz, Sneddon). The measured critical stresses for loop nucleation are in good agreement with theory of dislocations within the isotropic approach. Corresponding dislocation loops were proved by means of microscopy imaging techniques (transmission electron microscopy (TEM), cathodoluminescence imaging (CL), and imaging of dislocation-etched surfaces.
11th Conference on Hardness Measurement, Celle, Germany, 2002

E. Aslanyan, A. Doinikov
ON EXPRESSION OF HARDNESS MEASUREMENTS RESULTS UNCERTAINTY
Approach to hardness measurements data processing has been examined. The basis of this approach is that the scales of hardness are, in accordance with the general measurements theory, scales of order. The advantage of the method consists in the fact that it is more adequate and simple which is characteristic of hardness measurements as such.
11th Conference on Hardness Measurement, Celle, Germany, 2002

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