9762 papers found
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.
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...
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...
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...
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.
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...
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.
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...
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...
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...