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Indentation hardness

About: Indentation hardness is a research topic. Over the lifetime, 15834 publications have been published within this topic receiving 292983 citations.


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Journal ArticleDOI
TL;DR: In this article, the authors review the current understanding of the mechanics governing elastic-plastic indentation as they pertain to load and depth-sensing indentation testing of monolithic materials and provide an update of how they now implement the method to make the most accurate mechanical property measurements.
Abstract: The method we introduced in 1992 for measuring hardness and elastic modulus by instrumented indentation techniques has widely been adopted and used in the characterization of small-scale mechanical behavior. Since its original development, the method has undergone numerous refinements and changes brought about by improvements to testing equipment and techniques as well as from advances in our understanding of the mechanics of elastic–plastic contact. Here, we review our current understanding of the mechanics governing elastic–plastic indentation as they pertain to load and depth-sensing indentation testing of monolithic materials and provide an update of how we now implement the method to make the most accurate mechanical property measurements. The limitations of the method are also discussed.

6,616 citations

Book
05 Oct 2000
TL;DR: Hardness measurements with conical and pyramidal indenters as mentioned in this paper have been used to measure the area of contact between solids and the hardness of ideal plastic metals. But they have not yet been applied to the case of spherical indenters.
Abstract: 1. Introduction 2. Hardness measurements by spherical indenters 3. Deformation and indentation of ideal plastic metals 4. Deformation of metals by spherical indenters. Ideal plastic metals 5. Deformation of metals by spherical indenters. Metals which work-harden 6. Deformation of metals by spherical indenters. 'Shallowing' and elastic 'recovery' 7. Hardness measurements with conical and pyramidal indenters 8. Dynamic or rebound hardness 9. Area of contact between solids Appendix I. Brinell hardness Appendix II. Meyer hardness Appendix III. Vickers hardness Appendix IV. Hardness conversion Appendix V. Hardness and ultimate tensile strength Appendix VI. Some typical hardness values

3,562 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that the intrinsic correlation between hardness and elasticity of materials correctly predicts Vickers hardness for a wide variety of crystalline materials as well as bulk metallic glasses (BMGs).
Abstract: Though extensively studied, hardness, defined as the resistance of a material to deformation, still remains a challenging issue for a formal theoretical description due to its inherent mechanical complexity. The widely applied Teter's empirical correlation between hardness and shear modulus has been considered to be not always valid for a large variety of materials. The main reason is that shear modulus only responses to elastic deformation whereas the hardness links both elastic and permanent plastic properties. We found that the intrinsic correlation between hardness and elasticity of materials correctly predicts Vickers hardness for a wide variety of crystalline materials as well as bulk metallic glasses (BMGs). Our results suggest that, if a material is intrinsically brittle (such as BMGs that fail in the elastic regime), its Vickers hardness linearly correlates with the shear modulus (H(v) = 0.151G). This correlation also provides a robust theoretical evidence on the famous empirical correlation observed by Teter in 1998. On the other hand, our results demonstrate that the hardness of polycrystalline materials can be correlated with the product of the squared Pugh's modulus ratio and the shear modulus (H(v) = 2(k(2)G)(0.585) - 3 where k =G/B is Pugh's modulus ratio). Our work combines those aspects that were previously argued strongly, and, most importantly, is capable to correctly predict the hardness of all hard compounds known included in several pervious models. (C) 2011 Elsevier Ltd. All rights reserved.

1,632 citations

Journal ArticleDOI
TL;DR: In this article, a comprehensive computational study was undertaken to identify the extent to which elasto-plastic properties of ductile materials could be determined from instrumented sharp indentation and to quantify the sensitivity of such extracted properties to variations in the measured indentation data.
Abstract: A comprehensive computational study was undertaken to identify the extent to which elasto- plastic properties of ductile materials could be determined from instrumented sharp indentation and to quantify the sensitivity of such extracted properties to variations in the measured indentation data. Large deformation finite element computations were carried out for 76 different combinations of elasto-plastic properties that encompass the wide range of parameters commonly found in pure and alloyed engineering metals: Young's modulus, E, was varied from 10 to 210 GPa, yield strength, sy, from 30 to 3000 MPa, and strain hardening exponent, n, from 0 to 0.5, and the Poisson's ratio, n, was fixed at 0.3. Using dimensional analysis, a new set of dimensionless functions were constructed to characterize instrumented sharp indentation. From these functions and elasto-plastic finite element computations, analytical expressions were derived to relate inden- tation data to elasto-plastic properties. Forward and reverse analysis algorithms were thus established; the forward algorithms allow for the calculation of a unique indentation response for a given set of elasto-plastic properties, whereas the reverse algorithms enable the extraction of elasto-plastic properties from a given set of indentation data. A representative plastic strain er was identified as a strain level which allows for the construction of a dimensionless description of indentation loading response, independent of strain hardening exponent n. The proposed reverse analysis provides a unique solution of the reduced Young's modulus E*, a representative stress sr, and the hardness pave. These values are somewhat sensitive to the experimental scatter and/or error commonly seen in instrumented indentation. With this information, values of sy and n can be determined for the majority of cases considered here, provided that the assumption of power law hardening adequately represents the full uniaxial stress-strain response. These plastic properties, however, are very strongly influenced by even small variations in the parameters extracted from instrumented indentation experiments. Comprehensive sensitivity analyses were carried out for both forward and reverse algorithms, and the computational results were compared with experimental data for two materials.  2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.

1,299 citations

Journal ArticleDOI
TL;DR: In this paper, the authors measured the hardness of a thin epitaxial gold film embedded in the silver layers and found that the deformation was primarily restricted to the sharp edges of the indentation.
Abstract: The hardness of thick, high-purity, epitaxially grown silver on sodium chloride is found to be dependent on the size of the indentation for sizes below ≃10 μm. The measurement of the size effect has been made in two ways. In one, the hardness has been calculated from the load-displacement curve obtained from an instrumented microhardness testing machine and assuming a geometric self-similarity in the indenter shape. In the other measurement, the hardness was obtained from the load exerted by the microhardness tester divided by the indentation impression area as measured by atomic force microscopy. The observed variation in microhardness with indentation size is consistent with a simplified strain gradient plasticity model in which the densities of the geometrically necessary and statistically stored dislocations are fitting parameters. An equally good fit can also be made with a simple geometric scaling relationship. Transmission electron microscopy observations of a thin (≃50 nm) epitaxial gold film embedded in the silver layers revealed that the deformation was primarily restricted to the sharp edges of the indentation. In addition, deformation twinning within the indentation impression was observed on the {1H} planes.

1,259 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,448
20223,006
20211,016
20201,048
2019929
2018873