[en] The article presents a status report on standardisation efforts in the field of hardness testing, with particular regard to the Vickers hardness test. Here, standardisation work was carried out under German leadership in SSO/TC 164?SC 3. Further, information is presented on the Brinell and Rockwell hardness tests and on universal hardness

[en] It was shown that for boron carbide the law of similarity of Kick is valid in impression diagonals in the range of 11 to 14 μm. With 3,350 +- 150 kp/mm² the maximum hardness of boron carbide, according to Knoop as well as according to Vickers, corresponds to these impression diagonals. In case of impression diagonals exceeding 14 μm or being less than 11 μm the exponential function P = a x dsup(n) is satisfied with Meyer's exponents of n < 2 or n > 2. By graphically extrapolating the straight line according to Meyer with gradients n = 1.4 (Vickers) or n = 1.7 (Knoop), which characterizes the decrease of hardness with the increasing load a value of FK 100 and FV 34 of 1,300 p as indication of hardness is obtained. The range of homogeneity Bsub(4 + x)C as well as the grain size have no perceptible influence on hardness determination of boron carbide. (orig.)

[en] During the service life, the mechanical properties of the PWR components change. It is necessary to determine precisely this evolution, but it is not always possible to draw a sample with the adequate size for the characterization. For this latter case we intend to calculate the stress-strain curve of a material from a hardness test results, because it is appropriate for testing on site and do not need any particular sample shape. This paper is the first bibliographical part of a larger study on the relation between the values measured during a hardness test (applied load, indentation diameter) and the mechanical properties of a solid obtained by a traction test. We have treated the problem within the general setting of two solids in contact. Thus, we expose general elastic, elasto-plastic and plastic models describing the indentation of a solid by a rigid indenter

[en] The typical voltage comparator circuits are considered. Shown that the use of series- parallel connection of cascades improves the accuracy, speed and hardness to single event transient effects. (paper)

[en] The present work shows how data obtained in a depth-sensing indentation test using a Knoop indenter may be analyzed to provide elastic modulus and hardness of the specimen material. The method takes into account the elastic recovery along the direction of the short axis of the residual impression as the indenter is removed. If elastic recovery is not accounted for, the elastic modulus and hardness are overestimated by an amount that depends on the ratio of E/H of the specimen material. The new method of analysis expresses the elastic recovery of the short diagonal of the residual impression into an equivalent face angle for one side of the Knoop indenter. Conventional methods of analysis using this corrected angle provide results for modulus and hardness that are consistent with those obtained with other types of indenters

[en] To study the effects of zirconium (Zr) addition on the microstructure, hardness and the tensile properties of oxide dispersion strengthened (ODS) ferritic-martensitic steels, two kinds of 9Cr-ODS ferritic-martensitic steels with nominal compositions (wt.%) of Fe-9Cr-2W-0.3Y_2O-3 and Fe-9Cr-2W-0.3Zr-0.3Y_2O_3 were fabricated by the mechanical alloying (MA) of premixed powders and then consolidated by hot isostatic pressing (HIP) techniques. The experimental results showed that the average grain size decreases with Zr addition. The trigonal δ-phase Y_4Zr_3O_1_2 oxides and body-centered cubic Y_2O_3 oxides are formed in the 9Cr-Zr-ODS steel and 9Cr non-Zr ODS steel, respectively, and the average size of Y_4Zr_3O_1_2 particles is much smaller than that of Y_2O_3. The dispersion morphology of the oxide particles in 9Cr-Zr-ODS steel is significantly improved and the number density is 1.1 x 10"2"3/m"3 with Zr addition. The 9Cr-Zr-ODS steel shows much higher tensile ductility, ultimate tensile strength and Vickers hardness at the same time

[en] The change of hardness and structure of the zirconium surface after laser modification in air has been analyzed. The dependences of the hardness parameters and the nature of the surface structure on the laser processing regimes were determined. The hardness of the hard-facing layer of zirconium was increased to 25–34 GPa. (paper)

[en] Twelve steel works laboratories took part in the experimental programme carried out on the systematic study of the hardness-strength relationship for very diverse ranges of steels. The Rm strength regressions were calculated in terms of the Brinell and Vickers hardness numbers

[en] Short-fibre-reinforced resin composite has been recently proposed as a potential substructure in restorative dentistry. This study aimed to analyze the effect of short-fibre-reinforced resin composite (SFRC) thickness and curing time on its hardness and depth of cure (DoC). Twenty-four specimens of SFRC (EverX Posterior™) were prepared in cylindrical molds of 6 mm diameter and two different thicknesses (4 and 5 mm; n = 12 each). Each thickness group was cured with 2-mm light-curing distance at an irradiance of 800 mW/cm² for 25 and 30 s (n = 6 each). Hardness was measured by Vickers hardness test, and DoC was obtained by calculating the hardness ratio of the bottom-to-top surface (%). Data were statistically analyzed by one-way analysis of variance. In conclusion, the thickness and curing time had significant effect on the hardness and DoC of SFRC as a substructure. (paper)

[en] The authors develop the methods of hard-facing of mining-metallurgic equipment parts with heat-resisting high-hardness steels on the base of plasma-jet hard-facing in the shielding-alloying nitrogen atmosphere. (paper)