SU932371A1 - Method of material hardness determination - Google Patents

Description

The invention relates to testing equipment, and specifically to measuring the hardness of materials.

There is a method of determining hardness using a Bauman spring hammer. It involves applying with a striker a calibrated blow to a ball of a certain diameter, which is installed on the surface of the test material. Hardness is judged by the size of the imprint remaining after impact (1].

The disadvantages of the method are the need to first obtain a calibration dependence of the size of the fingerprint on the hardness and the complexity of taking into account changes in the parameters of the impactor (mass, impact force, etc.) in the process of operation.

Closest to the proposed technical essence and the achieved effect is a method for determining the hardness of materials, which consists in the fact that, under the action of an impact, an indenter is introduced into the test material, preliminarily determined; the dependence of the dynamic coefficient of hardness of a material on its static hardness and impact velocity, measure the diameter of the prints on top 10 (51) M. Kp. ³

G 01 N 3/48 (53) UDC 620.178 .153.2 (088.8)

the test material and determine the static hardness of the latter. him [2].

The disadvantages of the method are the need to use reference samples and: to ensure high uniformity of physical properties on the surface of the standard, as well as the need to measure the dimensions of the print not only on the surface of the test material, but on the standard, all this introduces errors in the measurement process.

The purpose of the invention is to increase the accuracy of determination of hardness.

This goal is achieved by the fact that they produce a shock with a known speed by a drummer with a known mass and determine the static hardness by the formula, b ...... Г _mVo η it Dh L ~~ o (n + 1)] (1) where η - dynamic coefficient of hardness;

D is the diameter of the indenter;

h is the depth of the residual imprint, measured from the level of the initial surface of the test material;

m and V _o - the mass of the striker and its speed at the point of impact with the indenter;

η and b are parameters depending on the hardness of the test material and the diameter of the indenter; $

The method is implemented as follows.

Pre-experimental ^; In this way, the dependence of the dynamic coefficient of hardness of materials on their static hardness and impact velocity is determined. The values of the total approximations and s / 2 are measured. at two arbitrary static loads P ^ and P-2 in the power contact of the indenter 5 with the surfaces of the auxiliary tiles, the hardness range of which includes the hardness of the test material, and the parameters 20 η and b are calculated from the obtained values using the known formulas where ^{η =} -igUT / ip ^{; b =}

For this indenter, the nature of the functional dependence of the parameters η and b on hardness is established.

After that, the indenter is introduced into the surface of the test material by a hammer with a known mass and at a known speed of impact. The depth or diameter of the residual imprint on the test surface is measured and the static hardness of the material is determined by the formula (1).

Thus, the proposed method allows to determine the static hardness of the material with the help of the parameters of the residual imprint obtained by using the impact, without the use of additional measurements on the standard and without the preliminary construction of calibration schedules.

Claims (2)

The invention relates to a test technique, in particular to measurements of the hardness of materials. There is a method for determining the hardness using a Bauman spring drummer. It involves striking a ball of a certain diameter using a striker, which is placed on the surface of the test material. Hardness is judged by the value of the flj. The disadvantages of the method are the need to preliminarily obtain a calibration dependence of the dimensions of a print on the hardness and the complexity of taking into account changes in the parameters of the impactor (mass, impact force, etc.) in the process of operation. The closest to the proposed technical essence and the achieved effect is a method for determining the hardness of materials, which consists in the fact that under the effect of an impact, an indenter is introduced into the test material, the dependence of the dynamic coefficient of hardness — the material on its static hardness and impact speed is preliminarily determined measure the diameter of the prints on the surface of the test material and determine the static hardness of the latter; 2. The disadvantages of the method are the necessity of using reference materials i and: ensuring a high uniformity of physical properties over the surface of the standard, as well as the need to measure print sizes not only on the surface of the test material, but also on the edge. All this introduces errors in the measurement process. The purpose of the invention is to improve the accuracy of hardness determination. This goal is achieved by striking a hammer at a known speed with a known mass and determining the static hardness by the formula (n -) (1) where Y is the dynamic hardness coefficient; D is the diameter of the indenter; h is the depth of the residual print measured from the level of the initial surface of the test material; m and Vjj is the mass of the striker and its velocity at the point of impact with the indenter; p and b are parameters depending on the hardness of the test material and the diameter of the indenter; The method is implemented as follows. The dependence of the dynamic hardness coefficient of materials on their static hardness and impact velocity is preliminarily determined experimentally. The values of complete convergence ct / and of g are measured with two arbitrary static loads P and E at the indenter’s force contact with the surfaces of auxiliary tiles, the hardness range of which includes the hardness value of the test material, and using the values obtained p and b by the known formulas lg (P./Pi). . k (2) For this indenter, the nature of the functional dependence of the parameters n and b on hardness is established. After this, the indenter is impacted into the surface of the test material by an impactor with a known mass and at a known impact rate. The depth or diameter of the residual imprint on the test surface is measured and the static hardness of the material is determined by formula (1). Thus, the proposed method makes it possible to determine the static hardness of a material with. parameters of the residual imprint obtained by means of the impact, without changing additional measurements on the standard and without first constructing calibration charts. The method of determining the hardness of materials, which implies an inventory of the material under test under the impact, preliminarily determines the dependence of the dynamic hardness coefficient of the material on its static hardness and the speed of the gift, measure the diameter of the prints, and determine the static hardness of the surface of the test material the latter, characterized in that, in order to improve the accuracy of the flow, a hammer with a known mass is struck at a known speed and a static kuyu hardness according to the formula where PI - dynamic coefficient of hardness; D is the diameter of the indenter; h is the depth of the residual print measured from the level of the initial surface of the test material; m and V is the mass of the impactor and its velocity at the point of impact with the indenter; , p and b are parameters depending on the hardness of the test material and the diameter of the indenter. Sources of information taken into account in the examination 1. Gogoberidze D.B. Hardness and; methods of its measurement. M, Mashgiz, 1952, p.207-208. 2. USSR author's certificate 280022, cl. G 01 N 3/48, 1968 (prototype) ..