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.
Joint International Conference on Force, Mass, Torque, Hardness and Civil Engineering Metrology in the age of globalization · TC5 · 2002 · Download
In a previous report, the authors investigated changes in hardness measurements when load rise time (LRT) was changed over a broad range in Vickers harness tests with loads of between 15 kgf and 150 kgf. As a result, we reported that hardness measurements varied according to the LRT value for every test load, while they remained almost constant between 15 kgf to 150 kgf if LRT was the same, although the indentation velocity of the indenter differed by more than three times between the two loads. It is very interesting that the considerable difference in indentation velocity due to varied...
Hardness Measurements Theory and Application in Laboratories and Industries · TC5 · 2004 · Download
This paper outlines the development of a simple predictive model for comparison of static and dynamic hardness. The model is essentially based on the energy - balance considerations and uses work of indentation divided by deforming volume to define hardness. The dynamic hardness was evaluated from measurements of residual contact dimensions and continued force - displacement over the velocity range 1 to 10 m s-1, based on the energy loss models and the energy conservation principle. The total and reversible work of indentation, defined as the respective area under the loading and unloading...
Hardness Measurements Theory and Application in Laboratories and Industries · TC5 · 2004 · Download
Based on the estimation of uncertainty the present requirements of the standard are discussed. Additional requirements needed for improving the reliability and the reproducibility are proposed. Especially the compliance of the machine affects strongly the parameters EIT and HMs in the macro range.
Hardness Measurements Theory and Application in Laboratories and Industries · TC5 · 2004 · Download
The direct verification and the calibration of Rockwell diamond cone indenters in NMLT and JBI are described. Developed instrument can verify the roundness of the spherical part of the indenters, measure the radius of indenter tip and the cone angle by the optical methods. The regression analysis of the geometry of indenters and hardness value can determine the bias of each indenter in each hardness level. This bias can be used to correct the hardness value. To investigate the availability of the correction of hardness value, the experiments were carried out to analyze the relation between...
Hardness Measurements Theory and Application in Laboratories and Industries · TC5 · 2004 · Download
Methods for hardness measurement on elastomers are characterized by a set-up where indenters with various defined geometries are pressed under defined test forces into the surface of testing material. The hardness value represents the resistance of the material to the rigid indenter and is calculated from the indentation depth of the indenter in the to be tested material. The test methods IRHD and Shore are the most common methods used in the field of rubber hardness measurements. Appropriate hardness measuring instruments are spread world wide. A periodic verification has to be carried out...
Hardness Measurements Theory and Application in Laboratories and Industries · TC5 · 2004 · Download
A national scale is set up for each hardness scale representing the reference hardness values in each country. From metrological and international trade aspects agreement between the national scales is very important. Good agreement makes possible good industrial cooperation. Therefore comparison between national scales is necessary. Comparison between national hardness scales and hardness scales set up by the producers of the reference blocks is necessary as well. The Rockwell measurement method is the most widely used hardness measurement method throughout the world. The measurement is...
Hardness Measurements Theory and Application in Laboratories and Industries · TC5 · 2004 · Download
It is desirable to measure the hardness of individual grains and microconstituents to have control over the mechanical properties of materials. An ultra-micro or nanoindenter is required to make indents small enough to fit inside a single grain or phases that is smaller than 10 mm diameter. Because the indents are too small for an optical microscope an atomic force microscope was used to view the location and measure the contact area. Measuring the contact area of indents from an atomic force microscope image is unreliable because it is difficult to manually locate the indent edge. To solve...
Hardness Measurements Theory and Application in Laboratories and Industries · TC5 · 2004 · Download
The mechanical properties of thin films can be measured by a variety of different techniques, with nanoindentation being one of the most recent developments in this growing field. By using a depthsensing indentation method it is possible to obtain quantitative values for the hardness and modulus, and thus gain better insight into the response of a material to controlled deformation at such small scales. However, previous work has shown that the effects of pile-up, particularly in soft films deposited on hard substrates, can produce significant overestimation of the hardness and modulus due...
Hardness Measurements Theory and Application in Laboratories and Industries · TC5 · 2004 · Download
George D. Quinn, Robert Gettings, and Lewis K. Ives
Standard Reference Material (SRM) 2831 was developed to improve Vickers hardness testing of Ceramics and Hardmetals. It may be used with conventional hardness testing machines that make indentations that are measured with an optical microscope. The SRM is a hot-isostatically pressed tungsten carbide with 12 % cobalt disk which has five indentations made at a load of 9.8 N (1 kgf). Each SRM is individually certified for the size of each of the 5 indentations, the average diagonal length ( 35.0 m), and the average hardness HV1. The HV1 is nominally 15 GPa which is in middle of the hardness...
Hardness Measurements Theory and Application in Laboratories and Industries · TC5 · 2004 · Download