SU1375994A1 - Method of estimating hardness of materials - Google Patents

Abstract

The invention relates to the testing of materials and can be used to assess hardness. The purpose of the invention is to improve accuracy. This is achieved by eliminating the effect of the thermal effect of the laser beam on the sample. The laser beam acts on the sample and registers the resulting acoustic emission signal (AE). A specimen of the same material is installed on the sample, the beam is applied to it and the AE signal is re-recorded in the sample. The AE signal arising in the sample when exposed through a contra-sample is due to their mechanical interaction and depends on the hardness of the sample material. A signal registered without a counter sample makes it possible to estimate the energy of this interaction. As a result, the ratio of the amplitudes of the AE signals registered with and without the counter sample allows one to carry out a rationing of the impact energy and to estimate the hardness of the material using this ratio using previously removed calibration dependencies. 1 hp f-ly. 2 Il. with (L

Description

The invention relates to material testing and can be used to evaluate hardness.

The purpose of the invention is to improve the accuracy due to the fact that acoustic emission (AE) is recorded, which occurs only due to the mechanical interaction of the sample and the counter sample.

FIG. 1 shows a scheme for implementing the method; in fig. 2 - graphic recording of AE signals recorded in the sample.

The method is carried out as follows.

On the table of the laser system 1 set the sample 2 with the prepared surface. Sensor 3 of the AE signals is fixed to the sample. A laser beam is applied to sample 2 and the AE signal from sensor 3 is recorded. The waveform of the AE signal, when exposed to a sample with a laser beam, is characterized by curve I (Fig. 2). On the prepared surface of sample 2, set up a contra-sample 4. A laser beam affects the contra-sample and record the AE signal that occurs in the sample during its mechanical interaction with the counter-sample. Curve II (figure 2) depicts the waveform of the AE when exposed to a contra-sample laser beam. The ratio of the amplitude h of the AE signal, measured without a counter piece, to the amplitude hj with a counter piece, makes it possible to judge the hardness of the sample.

Estimation of material hardness with respect to AE signals is carried out using the calibration dependence

hardness from this ratio, which is removed previously on samples with known hardness, and

for samples significantly different in chemical composition, separate calibration curves are constructed.

The range of the base area of the contra-sample S 0.98 must be held to enable maximum transfer of the beam energy. The value of the coefficient 0.9 is chosen empirically.

Claims (2)

1. A method for assessing the hardness of materials, which consists in applying a laser beam to a subject sample and record the acoustic emission signal, which is judged on the hardness of the material, characterized in that, in order to increase the accuracy, set the counter-sample, made of a sample material in the form of a truncated cone, with a smaller base on the sample surface to be tested, a laser beam is applied to the contra-sample, the acoustic emission signal is re-recorded in the test sample, the acoustic emission signals are compared and the hardness of the material is evaluated with regard to their ratio. 2. Method POP.1, characterized in that the area of the smaller base of the contra-sample is selected from the relation S 0.98, where 8 is the cross-sectional area of the laser beam. E Fi.1 Q 3 Figg