RU170693U1 - SAMPLE FOR MECHANICAL TESTS - Google Patents

Abstract

The utility model relates to mechanical tests designed to determine the mechanical properties of metals and their alloys, hardened using surface plastic deformation methods. The sample corresponds in shape and size to a standard proportional flat sample for mechanical tensile testing of thin plates and tapes, containing the head and the working part. A riveted surface layer is applied to the front and end surfaces of the working part. Effect: the ability to determine the strength of the riveted surface layer according to the results of standard mechanical tests for axial tension. 3 ill.

Description

The utility model relates to mechanical tests designed to determine the mechanical properties of metals and their alloys, hardened using surface plastic deformation methods.

One of the most important tasks of modern engineering is to ensure the necessary performance and durability of products in specified operating conditions. To solve this problem, various surface treatment methods are widely used (ultrasonic shock and shock laser treatments, shot peening and friction treatments, running-in, etc.), which increase the static and fatigue strength of engineering products by hardening the surface layers, creating residual compressive stresses in them, as well as the transfer of their structure to the nanocrystalline state.

To predict the destruction of materials with a riveted surface layer, it is necessary to determine the strength of this layer. However, hardened surface layers with a submicro- or nanocrystalline structure, as a rule, have a small thickness (several tens of micrometers); therefore, the manufacture of them is of micro samples for mechanical tests, such as for body-hardened nanostructured materials (Stolyarov V.V. Mechanical tests on stretching of nanostructured materials // Factory Laboratory. Diagnostics of materials. - 2008. - T. 74. - No. 1 - p. 54-57), is very laborious and does not exclude the introduction of a string into the fabricated sample. tural changes that may affect the results of mechanical tests.

A known sample for mechanical and structural tests, consisting of witness samples suitable for further research without additional mechanical processing and fixed on a base basis corresponding to standard samples for mechanical tests, in which witness samples are staggered on a basic basis in a checkerboard pattern along two axes symmetry, while the witness samples are electroplated coatings (patent RU 124803, G01N 3/00, 2013).

A known sample cannot be used to determine the strength of the riveted surface layer due to the impossibility of combining on the working surface of the witness specimen and the riveted surface layer.

Closest to the claimed utility model is a sample for testing a welded billet, corresponding in shape and size to standard flat samples with a longitudinally spaced weld for static tensile tests of thin plates and tapes of ferrous and non-ferrous metals to determine the characteristics of mechanical properties, in which the sample with applied coordinate grid of round cells made of a composite billet, welded from sheets of different thicknesses, strength or kind of material, has a sheet width of both sides of the weld, ensuring equal strength sheets on the sample (patent RU 2378634, G01N 1/28, G01N 3/08, 2010).

A known sample also cannot be used to determine the strength of the riveted surface layer due to the impossibility of combining on the working surface of the witness specimen and the riveted surface layer.

Thus, the authors were faced with the task of developing a sample for determining the strength of a riveted surface layer according to the results of standard mechanical tests for axial tension.

The problem is solved in the proposed sample for mechanical testing, corresponding in shape and size to a standard proportional flat model for mechanical tensile testing of thin plates and tapes containing heads and a working part, in which a riveted surface layer is applied to the front and end surfaces of the working part.

Currently, a sample for determining the strength of a riveted surface layer according to the results of standard mechanical tests for axial tension is not known from the patent and scientific literature.

In the case of hardening the surface layer of a material, in particular steel, by creating a riveted layer with a submicro- or nanocrystalline structure, it is practically impossible to measure its mechanical strength due to its insignificant thickness. The creation on the front and end surfaces of the working part of a flat sample corresponding in shape and size to a standard proportional flat sample with heads for mechanical tensile tests of thin plates and tapes of a riveted layer using surface plastic deformation, made it possible, firstly, to exclude thermomechanical effects on the riveted surface layer during the manufacture of the sample, which eliminated the change in the structure of the riveted surface layer during manufacture sample and, therefore, to exclude the influence of changes in the structure of the riveted surface layer on the results of mechanical tests, and secondly, to consider the sample with a riveted surface layer as a composite material consisting of a matrix and a strengthening layer, which allowed us to determine the strength of the riveted surface layer using the rule of mixtures .

The strength of the composite material is determined according to the rule of mixtures (Materials: Textbook for Universities / Under the general editorship of B.N. Arzamasov. - M .: Engineering, 1986 - 384 p.), Which with reference to the sample with a riveted surface layer has the form:

- временное сопротивление образца с наклепанным поверхностным слоем;Where

- temporary resistance of the sample with a riveted surface layer;

- временное сопротивление наклепанного поверхностного слоя;Where

- temporary resistance of the riveted surface layer;

- временное сопротивление матрицы;

- temporary resistance of the matrix;

- объемная доля наклепанного поверхностного слоя;

- volume fraction of the riveted surface layer;

t ^SL - the thickness of the riveted surface layer;

t ^ons is the thickness of the sample with a riveted surface layer.

определяют по результатам испытаний образца свидетеля. Таким образом

, где

- временное сопротивление образца-свидетеля.Matrix temporary resistance

determined by the test results of a witness sample. In this way

where

- temporary resistance of the witness model.

The strength of the riveted surface layer is determined from the condition:

Thus, the creation of a riveted layer by means of surface plastic deformation on the front and end surfaces of the working part of a flat sample, corresponding in shape and size to a standard proportional flat sample with heads for mechanical tensile tests of thin plates and tapes, makes it possible to determine the strength of the riveted surface layer by standard mechanical axial tensile test results.

A specimen for determining the strength of a riveted surface layer includes a specimen (1) corresponding in shape and size to a standard proportional flat specimen with heads for mechanical tensile testing of thin sheets and tapes, and a riveted surface layer (2) created on the front and end surfaces of the working part sample using surface plastic deformation and is illustrated by the following graphic materials:

- in FIG. 1 shows a sample for determining the strength of a riveted surface layer, front view;

- in FIG. 2 shows a sample for determining the strength of a riveted surface layer, top view;

- in FIG. 3 is a cross-sectional view of a sample for determining the strength of a riveted surface layer in a fracture zone.

The proposed sample for determining the strength of the riveted surface layer can be used as follows. A specimen (1) is made corresponding in shape and size to a standard proportional flat specimen with heads for mechanical tensile testing of thin plates and tapes according to GOST 11701-84. On the front and end surfaces of the working part of the sample using surface plastic deformation, for example, friction treatment (Makarov A.V. Nanostructural friction treatment of carbon and low alloy steels // In the book. Promising materials. Volume IV: Textbook / Ed. D. L. Merson. - Tolyatti: TSU, 2011 - 434 pp. - Chapter 3. - P. 123-208), create a riveted surface layer (2). Determine the thickness of the riveted surface layer, for example, by the method of microhardness (Khrushchev MN New in the field of tests for microhardness. - M .: Nauka, 1974 - 262 p.). A test specimen is made whose material, shape and dimensions are similar to the material, shape and dimensions of the sample with a riveted surface layer. A specimen with a riveted surface layer and a test specimen are tested for axial tension until fracture according to GOST 11701-84 on a tensile testing machine, for example, Instron 8801, and their strength is determined. Then determine the strength of the riveted surface layer from condition (b).

Thus, the authors propose a sample for mechanical testing, which makes it possible to measure the strength of a riveted layer with a submicro- or nanocrystalline structure by creating a sample in the form of a composite material, which makes it possible to use the rule of mixtures in the calculation of test results.

Claims (1)

A mechanical test specimen corresponding in shape and size to a standard proportional flat specimen for mechanical tensile testing of thin plates and tapes containing heads and a working part, characterized in that a riveted surface layer is applied to the front and end surfaces of the working part.

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