Special Issue "Instrumented Indentation Test: An Aiding Tool for Materials Science and Industry"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: 30 September 2021.

Special Issue Editors

Prof. Giovanni Maizza
E-Mail Website
Guest Editor
Politecnico di Torino, Turin, Italy
Interests: instrumented indentation testing; contact mechanics; micro–macro modeling of the multiphysical processing of materials; microstructure design of materials; microstructure–property–process parameter relationships
Prof. Dr. Dongil Kwon
E-Mail Website
Co-Guest Editor
Seoul National University
Interests: instrumented indentation testing; residual stress measurement; reliability assessment

Special Issue Information

Dear Colleagues,

It is believed that the instrumented indentation test (IIT) will revolutionize the industry in the next two decades, while continuing to lead to new elucidations about the nature and behavior of materials. It shares the same mechanical fundamentals as a conventional indentation test (IT), but it also permits a multitude of indentation properties, other than hardness, to be extracted in a quick, easy, and nondestructive manner. As such, it can be used either in offline or online manufacturing processes to assess the final mechanical performances of a part or to optimize the most relevant process parameters. IIT is particularly suitable for additive manufactured products, welded joints, and microelectromechanical devices, which generally lack a standard structural assessment. Although IIT can virtually be performed over nano-, micro- and macrodimensional scales, over the last decade, research into IIT has been dominated by nano-IIT studies, which have had a great impact on the progress of materials science and the thin film and coating industry. However, even greater impacts may be expected in the industrial sectors if macro-IIT comes into play, provided that appropriate guidelines are available. Macro-indentation properties correlate more naturally with the familiar tensile-like properties than nano-IIT ones do; thus, the macro-instrumented indentation test will offer an unprecedent viable nondestructive means of measuring tensile-like elastoplastic properties at a local scale in a wide range of metals and engineering alloys. The primary goal of this Special Issue is to present the recent advances in IIT research, with particular attention to macro-IIT achievements. The secondary goal is to provide comprehensive fundamental knowledge on IIT methodologies along with useful guidelines that are not covered by any available national or international standard, to permit IIT techniques to be exploited in new research and engineering fields. 

Prof. Giovanni Maizza
Prof. Dongil Kwon
Guest Editors

Manuscript Submission Information

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Keywords

  • Instrumented indentation
  • Indentation theory and modeling
  • Residual stress measurement
  • Field-assisted indentation
  • Materials: conventional bulk as well as nanocrystalline and porous metals and alloys
  • similar and dissimilar welded joints
  • Materials behavior: elastoplatic, superplastic, superelastic, recrystallization, creep, anisotropic
  • New in situ and ex situ inspection methodologies aiding materials characterization during indentation

Published Papers (6 papers)

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Research

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Open AccessArticle
Application of Macro-Instrumented Indentation Test for Superficial Residual Stress and Mechanical Properties Measurement for HY Steel Welded T-Joints
Materials 2021, 14(8), 2061; https://doi.org/10.3390/ma14082061 - 19 Apr 2021
Viewed by 327
Abstract
HY-80 and HY-100 steels, widely used in constructing large ocean vessels and submarine hulls, contain mixed microstructures of tempered bainite and martensite and provide high tensile strength and toughness. Weld integrity in HY steels has been studied to verify and optimize welding conditions. [...] Read more.
HY-80 and HY-100 steels, widely used in constructing large ocean vessels and submarine hulls, contain mixed microstructures of tempered bainite and martensite and provide high tensile strength and toughness. Weld integrity in HY steels has been studied to verify and optimize welding conditions. In this study, the T-joint weld coupons, HY80 and HY100, were fabricated from HY-80 and HY-100 steel plates with a thickness of 30 mm as base metals by submerged-arc welding. Flux-cored arc welding was performed on an additional welding coupon consisting of HY-100 to evaluate the effect of repair welds (HY100RP). Microstructures in the heat-affected zones (HAZ) were thoroughly analyzed by optical observation. Instrumented indentation testing, taking advantage of local characterization, was applied to assess the yield strength and the residual stress of the HAZ and base regions. The maximum hardness over 400 HV was found in the HAZ due to the high volume fraction of untempered martensite microstructure. The yield strength of the weld coupons was evaluated by indentation testing, and the results showed good agreement with the uniaxial tensile test (within 10% range). The three coupons showed similar indentation residual stress profiles on the top and bottom surfaces. The stress distribution of the HY100 coupon was comparable to the results from X-ray diffraction. HY100RP demonstrated increased tensile residual stress compared to the as-welded coupon due to the effect of the repair weld (323 and 103 MPa on the top and bottom surfaces). This study verifies the wide applicability of indentation testing in evaluating yield strength and residual stress. Full article
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Open AccessFeature PaperArticle
Flat-Top Cylinder Indenter for Mechanical Characterization: A Report of Industrial Applications
Materials 2021, 14(7), 1742; https://doi.org/10.3390/ma14071742 - 01 Apr 2021
Viewed by 313
Abstract
FIMEC (flat-top cylinder indenter for mechanical characterisation) is an instrumented indentation test employing a cylindrical punch. It has been used to determine the mechanical properties of metallic materials in several applications of industrial interest. This work briefly describes the technique and the theory [...] Read more.
FIMEC (flat-top cylinder indenter for mechanical characterisation) is an instrumented indentation test employing a cylindrical punch. It has been used to determine the mechanical properties of metallic materials in several applications of industrial interest. This work briefly describes the technique and the theory of indentation with a flat-ended punch. The flat indentation of metals has been investigated through experimental tests, and an equation has been derived to calculate the yield stress from the experimental data in deep indentation. The approach is supported by many data on various metals and alloys. Some selected case studies are presented in the paper: (i) crank manufacturing through pin squeeze casting; (ii) the evaluation of the local mechanical properties in a carter of complex geometry; (iii) the qualification of Al billets for extrusion; (iv) stress–relaxation tests on CuCrZr heat sinks; (v) the characterization of thick W coatings on CuCrZr alloy; (vi) the measure of the local mechanical properties of the molten-zone (MZ) and the heat-affected zone (HAZ) in welded joints. The case studies demonstrate the great versatility of the FIMEC test which provides information not available by employing conventional experimental techniques such as tensile, bending, and hardness tests. On the basis of theoretical knowledge and large amount of experimental data, FIMEC has become a mature technique for application on a large scale in industrial practice. Full article
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Open AccessArticle
Correlation Between the Indentation Properties and Microstructure of Dissimilar Capacitor Discharge Welded WC-Co/High-Speed Steel Joints
Materials 2020, 13(11), 2657; https://doi.org/10.3390/ma13112657 - 11 Jun 2020
Cited by 3 | Viewed by 598
Abstract
The welding of cemented carbide to tool steel is a challenging task, of scientific and industrial relevance, as it combines the high level of hardness of cemented carbide with the high level of fracture toughness of steel, while reducing the shaping cost and [...] Read more.
The welding of cemented carbide to tool steel is a challenging task, of scientific and industrial relevance, as it combines the high level of hardness of cemented carbide with the high level of fracture toughness of steel, while reducing the shaping cost and extending the application versatility, as its tribological, toughness, thermal and chemical properties can be optimally harmonised. The already existing joining technologies often impart either insufficient toughness or poor high-temperature strength to a joint to withstand the ever-increasing severe service condition demands. In this paper, a novel capacitor discharge welding (CDW) process is investigated for the case of a butt-joint between a tungsten carbide-cobalt (WC-Co) composite rod and an AISI M35 high-speed steel (HSS) rod. The latter was shaped with a conical-ended projection to promote a high current concentration and heat at the welding zone. CDW functions by combining a direct current (DC) electric current pulse and external uniaxial pressure after a preloading step, in which only uniaxial pressure is applied. The relatively high heating and cooling rates promote a thin layer of a characteristic ultrafine microstructure that combines high strength and toughness. Morphological analysis showed that the CDW process: (a) forms a sound and net shaped joint, (b) preserves the sub-micrometric grain structure of the original WC-Co composite base materials, via a transitional layer, (c) refines the microstructure of the original martensite of the HSS base material, and (d) results in an improved corrosion resistance across a 1-mm thick layer near the weld interface on the steel side. A nano-indentation test survey determined: (e) no hardness deterioration on the HSS side of the weld zone, although (f) a slight decrease in hardness was observed across the transitional layer on the composite side. Furthermore, (g) an indication of toughness of the joint was perceived as the size of the crack induced by processing the residual stress after sample preparation was unaltered. Full article
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Open AccessArticle
Nano-Indentation Properties of Tungsten Carbide-Cobalt Composites as a Function of Tungsten Carbide Crystal Orientation
Materials 2020, 13(9), 2137; https://doi.org/10.3390/ma13092137 - 05 May 2020
Cited by 2 | Viewed by 881
Abstract
Tungsten carbide-cobalt (WC-Co) composites are a class of advanced materials that have unique properties, such as wear resistance, hardness, strength, fracture-toughness and both high temperature and chemical stability. It is well known that the local indentation properties (i.e., nano- and micro-hardness) of the [...] Read more.
Tungsten carbide-cobalt (WC-Co) composites are a class of advanced materials that have unique properties, such as wear resistance, hardness, strength, fracture-toughness and both high temperature and chemical stability. It is well known that the local indentation properties (i.e., nano- and micro-hardness) of the single crystal WC particles dispersed in such composite materials are highly anisotropic. In this paper, the nanoindentation response of the WC grains of a compact, full-density, sintered WC-10Co composite material has been investigated as a function of the crystal orientation. Our nanoindentation survey has shown that the nanohardness was distributed according to a bimodal function. This function was post-processed using the unique features of the finite mixture modelling theory. The combination of electron backscattered diffraction (EBSD) and statistical analysis has made it possible to identify the orientation of the WC crystal and the distinct association of the inherent nanoindentation properties, even for a small set (67) of nanoindentations. The proposed approach has proved to be faster than the already existing ones and just as reliable, and it has confirmed the previous findings concerning the relationship between crystal orientation and indentation properties, but with a significant reduction of the experimental data. Full article
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Open AccessArticle
Relationship of Stiffness-Based Indentation Properties Using Continuous-Stiffness-Measurement Method
Materials 2020, 13(1), 97; https://doi.org/10.3390/ma13010097 - 24 Dec 2019
Cited by 2 | Viewed by 737
Abstract
The determination of elastic modulus (E) and hardness (H) relies on the accuracy of the contact area under the indenter tip, but this parameter cannot be explicitly measured during the nanoindentation process. This work presents a new approach that [...] Read more.
The determination of elastic modulus (E) and hardness (H) relies on the accuracy of the contact area under the indenter tip, but this parameter cannot be explicitly measured during the nanoindentation process. This work presents a new approach that can derive the elastic modulus (E) and contact depth (hc) based on measured experiment stiffness using the continuous-stiffness-measurement (CSM) method. To achieve this, an inverse algorithm is proposed by incorporating a set of stiffness-based relationship functions that are derived from combining the dimensional analysis approach and computational simulation. This proposed solution considers both the sink-in and pile-up contact profiles; therefore, it provides a more accurate solution when compared to a conventional method that only considers the sink-in contact profile. While the proposed solution is sensitive to Poisson’s ratio (ν) and the equivalent indentation conical angle (θ), it is not affected by material plasticity, including yield strength (σy) and work hardening (n) for the investigated range of 0.001 < σy/E < 0.5. The proposed stiffness-based approach can be used to consistently derive elastic modulus and hardness by using stiffness and the load-and-unload curve measured by the continuous-stiffness-measurement (CSM) method. Full article
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Review

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Open AccessReview
Pop-In Phenomenon as a Fundamental Plasticity Probed by Nanoindentation Technique
Materials 2021, 14(8), 1879; https://doi.org/10.3390/ma14081879 - 09 Apr 2021
Viewed by 336
Abstract
The attractive strain burst phenomenon, so-called “pop-in”, during indentation-induced deformation at a very small scale is discussed as a fundamental deformation behavior in various materials. The nanoindentation technique can probe a mechanical response to a very low applied load, and the behavior can [...] Read more.
The attractive strain burst phenomenon, so-called “pop-in”, during indentation-induced deformation at a very small scale is discussed as a fundamental deformation behavior in various materials. The nanoindentation technique can probe a mechanical response to a very low applied load, and the behavior can be mechanically and physically analyzed. The pop-in phenomenon can be understood as incipient plasticity under an indentation load, and dislocation nucleation at a small volume is a major mechanism for the event. Experimental and computational studies of the pop-in phenomenon are reviewed in terms of pioneering discovery, experimental clarification, physical modeling in the thermally activated process, crystal plasticity, effects of pre-existing lattice defects including dislocations, in-solution alloying elements, and grain boundaries, as well as atomistic modeling in computational simulation. The related non-dislocation behaviors are also discussed in a shear transformation zone in bulk metallic glass materials and phase transformation in semiconductors and metals. A future perspective from both engineering and scientific views is finally provided for further interpretation of the mechanical behaviors of materials. Full article
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