SU1731833A1 - Method of testing of alloy impact strength - Google Patents

Abstract

The invention relates to metallurgy, in particular to methods for determining the physicomechanical properties of steels and alloys. The purpose of the invention is to reduce the complexity of the measurement. The method includes fixing the decay of a solid phase carried out with the help of an electric discharge, with a pronounced selectivity of destruction, plotting the curvature curves, finding toughness according to the reference curve (S), where S is the area difference under the curvature curves. The method makes it possible to significantly reduce the labor intensity and the measurement time of the impact strength. 2 ill., 1 tab.

Description

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The invention relates to the field of solid state physics, namely to the study of the properties of solid materials at high and low temperatures, and can be used to determine the operational characteristics of creating materials with desired properties in the metallurgy of alloys.

The known Charly method is a dynamic test for the impact bending of rigorous rectangular-shaped specimens, which consists in evaluating the performance of the material under difficult loading conditions and its tendency to brittle fracture. The method provides for a strict unification of sample sizes and test conditions, since the law of liking does not apply to dynamic tests. The specimen is mounted on two poles of a tiller headlight and is hit from the side opposite to the U-notch in

plane perpendicular to the longitudinal axis of the sample. In this case, the angles of the tomb lifting with weight P and length I are fixed to "1 and after" 2 destruction of the sample. Impact viscosity is determined by the formula: where AH is the work expended on the deformation and destruction of the sample: An P I (cos a -cos%) F is the cross-sectional area of the sample at the cut point before testing. The method is used in the selection and acceptance control of metals and alloys to establish standards for samples with a V-shaped concentrator.

The main disadvantages of this method are considerable labor intensity and high metal intensity.

The closest in technical essence to the present invention is a method for quantifying the thermal stability of the phases of metals and alloys, which consists in fixing the decomposition of a solid

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phase and evaluating the tendency of the studied phase to destruction. The decomposition of the solid phase is carried out using a local effect of an electrical discharge on the phase of the sample separated by a microscope. The relative value of the thermal stability of this phase is judged by the period of its existence, which is identified with the time of preliminary search. The latter is determined from the obscuration curve: the empirical time dependence of the measured blackening density of spectral lines. On this curve, each point of which is obtained from 9 ... 11 parallel measurements, cut off the area corresponding to the regular flow of elements from the phase under investigation into the discharge cloud and called the time of preliminary survey. The absolute value of the thermal stability of the phases, expressed in terms of the energy of sublimation, is found from an empirically established dependence of the time of the survey on the energy of sublimation. The relative standard deviation of the method for determining the thermal stability of the phases is 0.095. The advantage of this method is to reduce the labor and metal consumption compared to the existing,

However, the method requires for its implementation of the preparation and etching of thin sections, which is a time-consuming operation. In addition, the method involves the use of a microscope, usually not supplied in the complete set of domestic equipment, to isolate the studied phase, which complicates obtaining results.

The aim of the invention is to reduce the labor intensity in determining the toughness of intergranular fracture alloys.

The goal is achieved in that the impact on the surface of the control and test specimens is carried out by a spark discharge in the mode of selective erosion of the material, which is expressed in the destruction of the embrittling solid phase. Impact strength, depending on the number of the embrittling phase, is judged by the empirically established dependence of electric spark erosion, identified with the area difference under the search curves in the non-equilibrium stage of the control and test samples, on the impact toughness of the alloys, and an - f (S) . The table shows the toughness values of the steels found from the proposed an and known methods.

FIG. 1 shows the curves of the survey of alloys, such as steel type

03X11H110M2T1, (r): 1 - for a control sample that has been heat-treated for 1 hour at, K and cooled in water; 2 — for a test specimen that has been heat-treated for 1 hour at, K and cooled in an oven; the shaded area corresponds to the area difference under the tracelines in the non-equilibrium stage, (r), T.e. parameter

S.

FIG. Figure 2 shows the reference curve for the dependence of toughness an on the parameter S for samples with known toughness: the parameter S is written for ionic

Titanium lines in steels x of type 03X11H10M2T1 TiH 308.88 nm).

The invention is carried out as follows.

Attract arbitrary samples

sizes weighing at least 30 g, the working surface of which is brushed on the diamond wheel to an RZ roughness of no more than 20 microns. The breakdown of brittle structural components is carried out by exposing the surface of samples to a high-voltage condensed spark discharge, for example, from an IG-3 generator in the mode of pronounced selectivity of material erosion: the current strength in the primary circuit

transformer 1.8 ... 2.0 A, voltage 220V, analytical gap 1.5 mm, auxiliary gaiter 2.5 mm, counter-electrode - angular core ju 6 mm, sharpened to a truncated cone or hemisphere.

On a microphotometer, for example, MF-2, photometry, measurement of blackening density Ј of spectral lines of brittle structural elements, such as TI P308.88 nm titanium in titanium carbide of a test specimen of type OZH11N10M2T1 steel, heat treated for 1 hour at a temperature of 873, K followed by cooling in the oven, during

all spectrograms recorded for moving in the time of the search of r with a given step (the step is chosen so that the blackening of the spectral lines does not go beyond 0.40 ... 1.80) to a photographic plate of the spectral instrument, such as an ISP-30 spectrograph. Having the parameters Ј and g, plot the curves (t), the so-called obscure curves. Typical obscure curves are shown in FIG.

Under the initial portion of the curve of the search (t), bounded along the abscissa, the value of the time of the search required to establish a regular mode of intake of a substance, for example

40 seconds in FIG. 1, the area is measured using a planimeter or other method, which, for example, for a control sample (in FIG. 1, curve 1) is equal to 20.6 J s. Similarly, find the area for the test specimen. The area difference under the search curve for the control and test specimens is then determined and a parameter S is obtained, for example, 5.4 J s. Next, a reference curve of impact strength, an, on parameter S, is constructed for standard samples with known impact strength (S). A similar curve is shown in FIG. 2

Find the toughness value of the test specimen with the parameter S set, for example, equal to 5.4 Js, along the curve (S) shown, for example, in FIG. 2. It is 1.8–105 J m 2, the relative standard deviation is 0.07.

The positive effect from the use of the invention is to reduce the labor intensity by three times compared with the known methods and reduce the metal intensity.

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Claims (1)

Invention Formula A method for determining the toughness of alloys, including sample preparation, exposure to their surface by a spark discharge, and fixation of solid phase decomposition, characterized in that, in order to reduce labor intensity, the test and test specimens are exposed to the surface with a spark explosion, which destroys the embrittlement solid. phase, photometry is carried out, the density of the blackening of the spectral lines of the elements of this phase is measured, the curves of the dependence of the blackening density (Ј) on the time of the survey (t) (r) are determined, the area difference under the Ј f (r) curves is obtained and the parameter S is obtained, a reference curve of toughness versus parameter S is plotted for samples with known toughness (S), and the toughness for the test sample is found from the reference curve (S) where en is 0 impact viscosity, J m, S is the difference of the area of 25 spans under the curves Ј f (r), the parameter S, J s. R -2 ft 6 , $ zhm  S W & X-C (Rig 2