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[en] The judgement of the ball hardness is often made by the basic knowledge of the year 1900. Hereby a hardness value is determined that is neither a geometrical nor a material based constant value. In newer literature a mathematical and material constant value is exhibited that can be recorded by practical depth measurements. This constant value agrees with the Brinell hardness HB in the case of the mark h = D/4 and excludes almost every cold shaping. The knowledge based on this results are transferred to a testing device in a constructive way. (orig.)
[de]Das Beurteilen der Kugeleindruckhaerte geschieht oft noch nach den Anfangskenntnissen von 1900. Hiernach wird ein Haertewert ermittelt, der weder einen geometrisch noch stofflich begruendeten Festwert darstellt. Im neueren Schrifttum wird mathematisch und stofflich ein Festwert ausgewiesen, der praktisch durch Tiefenmessung erfasst werden kann. Dieser Festwert stimmt bei der Eindrucktiefe h = D/4 mit der Brinellhaerte HB ueberein und schliesst nahezu die Kaltverformung aus. Die hierauf basierenden Erkenntnisse werden konstruktiv auf ein Haertepruefgeraet uebertragen. (orig.)
[en] The convenient procedure of deriving hardness from depth-sensing measurement is well compatible with conventional hardness concepts, despite of some peculiarities. By applying two independent and largely non-arbitrary corrections the results derived from the load vs. depth curves can be made more useful: The correction with respect to resilience provides compatibility with Vickers hardness. Deriving hardness without referring to the cumbersome zero depth point suppresses the load dependence. (orig.)
[en] The wear resistance in dry friction of two electrolytic and two pVD hard chromium coatings deposited on construction steel substrates is studied by means of standard pin on disc multi-pass, unidirectional operation. For both of these friction modes low cycle high load operation with cemented carbide pins leads to essentially coatings hardness controlled, abrasive wear. For these well adhering commercial coatings (both for through thickness cracking and for spalling failure) assessed by standard testing, are inadequate for quality ranking with respect to wear resistance. Steady state friction corresponds to a stabilised third body essentially composed of chromium oxide. (authors). 13 refs., 7 figs., 1 tab
[en] Hot stamping of quenchenable ultra high strength steels currently represents a promising forming technology for the manufacturing of safety and crash relevant parts. For some applications, such as B-pillars and other structural components that may undergo impact loading, it may be desirable to create regions of the part with tailored mechanical properties. In the paper, a laboratory-scale hot stamped U-channel was manufactured by using a segmented die, which was heated by cartridge heaters and cooled by water channels independently. Local hardness values as low as 289 HV can be achieved using a heated die temperature of 400°C while maintaining a hardness level of 490 HV in the fully cooled region. If the die temperature was increased to 450°C, the Vickers hardness of elements in the heated region was 227 HV, with a reduction in hardness of more than 50%. Optical microscopy was used to verify the microstructure of the as-quenched phases with respect to the heated die temperatures. The FE model of the lab-scale process was developed to capture the overall hardness trends that were observed in the experiments
[en] The variation of hardness of rhombohedral single crystals of calcite with orientation of longer diagonal of Knoop indenter with respect to direction  on a cleavage plane (100) is studied. The Knoop hardness number H which has a constant value in the range of high loads (40-80 g) varies with orientation A and quenching temperature. By following phenomenological approach, an empirical relation (√HA=mA+C is developed from these studies. The effects of crystal anisotropy and thermal treatment of specimens after indentation are also discussed. (orig.)
[en] During the first 7 yr of the INTEGRAL mission (2003-2009), Cyg X-1 has essentially been detected in its hard state (HS), with some incursions in intermediate HSs. This long, spectrally stable period allowed in particular the measurement of the polarization of the high-energy component that has long been observed above 200 keV in this peculiar object. This result strongly suggests that here we see the contribution of the jet, known to emit a strong synchrotron radio emission. In 2010 June, Cyg X-1 underwent a completed transition toward a soft state (SS). It gave us the unique opportunity to study in detail the corona emission in this spectral state, and to investigate in particular the behavior of the jet contribution. Indeed, during the SS, the hard X-ray emission decreases drastically, with its maximum energy shifted toward lower energy and its flux divided by a factor of ∼5-10. Interestingly, the radio emission follows a similar drop, supporting the correlation between the jet emission and the hard component, even though the flux is too low to quantify the polarization characteristics.
[en] Highlights: • New application of LIBS in industry. • Hardness of metallic alloys estimation using LIBS calibration curves. • Linear correlation between the plasma temperature and the hardness of metallic alloys. • The shock wave is fast when the material is hard. - Abstract: Surface hardness is a very important characteristic of metals. Its monitoring plays a key role in industry. In the present paper, using laser induced breakdown spectroscopy (LIBS), Fe–V18%–C1% alloys with different heat treatments have been used for making the correlation between surface hardness and laser-induced plasma temperatures. All investigated samples were characterized by the same ferrite phase with different Vickers surface hardnesses. The differences in hardness values were attributed to the crystallite size changes. A linear relationship has been obtained between the Vickers surface hardness and the laser induced plasma temperature. For comparison the relation between surface hardness and the ratio of the vanadium ionic to atomic spectral lines intensities (VII/VI) provided good linear results too. However, adopting the proposed approach of using the plasma temperature, instead, is more reliable in view of the difficulties that could be encountered in choosing the proper ionic and atomic spectral lines. To validate this approach we have investigated the shock wave speed induced by laser interaction with the used samples. It was found that harder is the material faster is the shock wave. The determination of the surface hardness via measuring Te shows the feasibility of using LIBS as an easy and reliable method for in situ industrial application for production control
[en] Intermetallic-based materials are interesting for high temperature structural applications because of their good mechanical properties and enhanced oxidation resistance. In this study microstructural examination of the Nb-Si-B alloys at Nb-rich compositions was performed. The Nb-rich corner of the Nb-Si-B system is very attractive because the constituent phases are Nb (a ductile and tough phase with a high melting temperature) and T_2 (a very hard intermetallic compound with favorable oxidation resistance), which make a good combination for high temperature structural materials. At compositions lower than 82 at%Nb the microstructure shows the T_2 primary phase and eutectic (T_2+Nb), while the Nb primary phase and eutectic were formed at higher compositions. Hardness tests (Rockwell A-scale and micro Vickers) were carried out to estimate the optimal composition for good mechanical properties.
[en] Ion implantation causes changes in mechanical properties such as hardness and fracture toughness on the ion-implanted surface. The purpose of this study is to experimentally investigate the effects of substrate temperature during ion implantation on the hardness and fracture toughness of an ion-implanted silicon wafer. A silicon (1 0 0) wafer was implanted by 3 MeV ions of Au and Si at different substrate temperature of 100, 200 and 300 K, respectively. After ion implantation, Vickers indentation experiments were carried out on the ion-implanted surface of the silicon wafer at room temperature. The results of the Vickers indentation tests show a significant decrease of hardness and an increase of fracture toughness of the ion-implanted silicon with decreasing the substrate temperature during ion implantation. It was found that the lower the substrate temperature during implantation, the greater the effectiveness of ion implantation on the changes in mechanical properties of the ion-implanted silicon