Hardness diamond pyramid

Vickers Hardness. The Vickers or diamond pyramid hardness (DPH) developed in 1924 was an improvement over the Brinell test. The Vickers test used a pyramidal diamond as the indenter. This permitted the hardness testing of much harder materials, and the constant 136° angle of the indenter eliminated the problem of variable indentation shape encountered using spherical indenters (1). 

The Vickers hardness test, developed in the United Kingdom, is more popular there than in the United States. VHN (Vickers hardness number) and DPH (diamond pyramid hardness) are synonymous terms. 

Nine strips of pure, fully annealed copper were deformed plcistically by being passed between a pair of rotating rollers so that the strips were made thinner and longer. The increases in length produced were 1,10, 20, 30, 40, 50, 60, 70 and 100% respectively. The diamond-pyramid hardness of each piece was measured after rolling. The results were... 

Assuming that a diamond-pyramid hardness test creates a further nominal strain, on average, of 0.08, and that the hardness value is 3.0 times the true stress with this extra strain, construct the curve of nominal stress against nominal strain, and find ... 

Ainsworth L., 1954, The diamond pyramid hardness of glass in relation to the strength and structure of glass, Jour. Soc. Glass Techrt., 38, 479-500. 

A No known as Diamond Pyramid Hardness. Indcnter is a square-hased diamond pyramid with included angle between faces of 136°. Loads may vary1 from 1 to I 20 kilograms with 10. 30. and 50 kilograms in common use. Hardness is equal to load (kilogramsi divided hy surface area (square millimeter) of the permanent indentation, ll is determined directly from oplical measurements of the diagonals of the indentation, which appear square at Ihe surface of the metal. 

On the other hand, Fein s [49] extensive study of transition temperatures and scuffing in pure sliding with the four-ball machine showed the same type of response to the velocity/load ratio that he found with the two-disk machine [44]. The sliding speeds ranged from 0.0002 to 68.6 cm/s, the loads from 19.6 to 88.2 N (2-90 kg). Two kinds of steel specimen sets were used hardened AISI 52100, diamond pyramid hardness 740, and heat-treated AISI 4140, hardness 270. There were 13 different lubricants, with the properties shown in Table 15-7. At low rubbing speeds the interfacial flash temperatures were negligible and the bulk temperatures of the lubricant were taken to be the transition temperatures. At speeds above 0.359 cm/s a particularized form of the flash temperature equation was used to calculate the contribution from interfacial rubbing to be added to the bulk temperature to obtain the transition temperature. 

There are a variety of types of hardness tests, but the most popular in the case of rare earth metals seems to have been the Brinell test and the Vickers, or Diamond Pyramid Hardness (DPH) test as it is most commonly called. The DPH test is perhaps the most reliable hardness test and, in fact, should give hardness values in close agreement with the results of properly conducted Brinell and Knoop (when loads are >500 g) hardness tests. Consequently, the emphasis in this section is on DPH data, but Brinell data are also presented where they are instructive. Frequently, microhardness data are quoted in the rare earth literature. Since they are determined with a diamond pyramid indenter using lower loads than macrohardness, the author includes them with DPH values when they are in agreement with macroscopic values although it is recognized that microhardness results can be load sensitive. 

Fig. 8.1. A bar graph summary of room temperature diamond pyramid hardness values of the rare earth metals including melting temperatures (K) and room temperature crystal structures. Solid portions of the bars indicate the lowest known value while the cross-hatched portions represent the range of values reported.

Fig. 12.4 Young s modulus, E, shear modulus, G, Debye temperature, Bp, and Vickers hardness, as functions of composition in quenched Ti-V alloys. References [Fed73] (Hand G), [Col84, p. 119] (5-kg diamond-pyramid hardness,...

Isothermal aging curves for alloy aged at 773 and 873 K after water quenching from the p field. Chemical composition 5.48 wt% Al, 0.072 wt% Fe, 6.35 wt% Mo, 0.004wt% N, 0.083 wt% 0,1.94 wt% Sn, and 4.00 wt% Zr. Beta transus temperature was 1211 K. Alloy used was in the form of flat bar stock previously warm worked in the a+p field. Hardness determinations were obtained on electro-polished specimens using a Zwick diamond pyramid hardness tester at a load of 10 kg. 

Metal Tensile strength (10 dyncm" ) Yield strength (10 dyncm ) Elongation (% in 50 mm) Diamond pyramid hardness... 

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