THE THIRD INTERNATIONAL CONFERENCE ON "MEASUREMENT OF

HARDNESS IN THEORY AND PRACTICE "

V. V. Varnello and N. P. Slavina

The third International Conference on nMeasurements of Hardness in Theory and Practice," organized by the Union of German Engineers in conjunction with the State Administration for Testing Materials of North Rhine- Westphalia, was held in Dortmund (PGR) September 23-25, 1959.

Some 300 delegates from Britain, Austria, Hungary, Italy, GDR, Poland, USSR, USA, France, FGR, Sweden, and Iapan and representatives of industry in the PGR took part in the conference. At the three plenary ses,- sions of the Conference 97 papers were read on various aspects of measuring hardness and microhardness, including the problems of the physical basis of hardness measurements.

The USSR delegates read two papers which were presented by the D. L Mendeleev Scientific Research In- stitute and aroused great interest among the delegates.

In the paper entitled "A method adopted in the USSR for testing conical-and pyramid-shaped diamond tips" (Candidate of Technical Sciences V. V. Varnello) the testing method was described, and a new method outlined of investigating the shape of the working part of a diamond tip by means of obtaining on a special press lamina- tion diagrams which make it possible to judge the defects in the shape of a tip.

The paper entitled "Reference instruments developed by the VNIIM for measuring hardness by the Rockwell or Vickers methods," read by the USSR delegation (Candidate of Technical Sciences N. P. Slavina) dealt with the new reference instruments, developed by the All-Union Scientific Research Institute of Metrology (VNIIM) and de- signed for calibrating hardness measures in HR and HV scales. High precision of measurement is provided by:auto,- marion, the reproducibility with great constancy of the pressing-in process, a high precision measurement of defor- mations attained by using optical devices with small graduations (0.15 ~ for the Rockwdl and 0.3 /J for the Vickers method), and by a great rigidity of all the instrument components, which eliminates any elastic strains occurring as the resuh of measurements.

Professor Kapler's paper (FGR) was very in.- Hardness HB, Y0 in tension, teresting from the point of view of showing the re-

Metal kg-wt /mm ~ kg-wt /mm 2 lation between hardness and other mechanical pro- perties. In his paper he put forward two problems

Aluminum 13.0 13.0 in measuring hardness:

Copper 31.0 30.I i) establishing a relationship between the hardness numbers obtained by pressing in tips of

Nickel 61.0 59.'/5 various shapes;

Iron 54.0 531/5 2) establishing the relationship between hard- ness numbers and other plastic characteristics of metals determined from tensile and twisting tests.

The paper provides for certain pure metal constants, which are obtained from tensile and twisting tests, and closely correspond to Brinell hardness numbers (see table).

Akashi (Japan)and Boucle (France)dealt in their papers with the interesting problem of measuring micro- hardness, for instance, the effect of a load and the speed of its application on the microhardness numbers.

The Central Institute for Supervision of Weights and Measures (Tokyo) presented a paper on a new optical method of measuring microhardness. The maximum effort used for pressing in the tip into the sample under test is 1500g-wt and the tip used consists of a diamond Vickers pyramid; the time of pressing and loading should not exceed 100 sec.

The diagrammatic recording apparatus provides agreat ly enlarged curve of the impression in terms of depth of impression against load. The effort is applied to the tip by means of weights "floating n in water when the water is let out.

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In his paper on standardization of hardness measurements with small loads, Prof. Boucle noted that the largest

dispersion of mtcrohardness values occurs when it is determined at loads below 10 g-wt. At loads between I and 3 g-wt the dispersion often exceeds 100%, at loads between 100 and 200 g-wt it is 10%, and above 3000 g-wt it

is only 3%.

The mlcrohardness of alloys depends substantially on the load at which it is measured, Thus, the micro- hardness of an alloy determined at loads of 5, 10, and 20 g-wt changes in the following manner: Hag = 260,

H10 g = 232, and H20/~ = 185.

In conclusion, it was pointed out that the measurement of microhardness was a very complicated and pressing problem and that the standardization of hardness measurements at small loads is an urgent task for the institutes

dealing with standardization.

The exceptional interest taken in the work of the conference by the delegates of all the countries should be noted. The growing interest in the work of the conference is due to the pressing nature of the questions discussed and the concern with many theoretical and practical problems in the measurement of hardness and microhardness.

C O N F E R E N C E FOR THE E X C H A N G E OF EXPERIENCE IN

I N T R O D U C I N G NEW MEASUREMENT T E C H N I Q U E S

D. M. Sizov

A regional conference of the heads of industrial laboratories called for the exchange of experiences in intro- ducing new measurement techniques, and organized by the Zaporozh'e State Inspection Laboratory in conjunction with the Central Bureau of Technical Information of the Zaporozh'e Council of National Economy, was held in Zaporozh'e in August, 1959. The conference was attended by 64 representatives of 32 industrial establishments of the Zaporozh'e Council of National Economy.

Two reports Were made at the conference. In the first it was noted that the work of the Central Test Labo- ratories in introducing new measurement techniques at the plants has two aspects:

1) the introduction of new techniques and modernization of the equipment possessed by the laboratories;

2) the introduction of better inspection methods in the production of components.

The Central Test Laboratory carried out the following work:

1) it produced a new spindle for a horizontal telescope caliper thus increasing its range of measurement;

2) it modified a telescope height gage for three-dimensional measurements by changing the construction of its table;

3) it combined an optical dividing head with an optical distance gage for measuring details with regularly placed spline teeth along a circumference. This device provides an accurate measurement of the angular posi- tion of teeth components;

4) it produced a sine-measuring table with a double slope for checking fiat surfaces at various angles;

5) it constructed an instrument for checking guiding surfaces in mills which measuresboth the conditions of the surfaces and their parallelism.

The introduction of better inspection methods in the production of components raised labor productivity and decreased scrap .

A large number of measuring instruments which check the dimensions of details in production have been installed on grinding machines at the last stage of manufacture. Thus the number of rejects was considerably de- creased.

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