SU796743A1 - Specimen for testing metals for corrosion under stress - Google Patents

Description

one

The invention relates to a test apparatus, namely to samples for testing metals for corrosion under stress.

A well-known sample for testing metals for corrosion under stress, made in the form of a ring, in the diameter of which a proppant l is placed.

The disadvantage of this sample is the laboriousness of making the ring from the metal under study.

Closest to the proposed technical entity is a test for metals for corrosion under stress, made in the form of a plate from the test material with two longitudinal slits, in the middle of the side bridges there are transverse slits for the proppant and on opposite side side surfaces. jumpers placed anti-friction pads 2.

The disadvantage of this sample is its low accuracy, since the contact area of the wedge with the jumper is large, which leads to contact at certain points in connection with low accuracy of wedges.

The leaks between the edges of the wedges and grooves are foci of corrosion in the contact zone, leading to a change in the initial state of the sample and, thus, to a decrease in the accuracy of the tests.

The purpose of the invention is to improve the accuracy of the tests.

This goal is achieved by the fact that the transverse slit is made in the middle jumper, and on the opposite surfaces of the crush formed symmetrical with respect to the longitudinal and transverse axes of the sample protrusions of trapezoidal section, the area F of the smaller base of each of them is chosen

FP

61 "61

t

AT

FO total cross-sectional area

P (T side trans B1chek; given level of normal stresses in side peremlchkah,

Claims (2)

 - respectively, the yield strength and tensile strength of the sample material. FIG. 1 shows a sample. General view; in fig. 2 shows a section A-A in FIG. 1 in FIG. 3 shows a section BB in FIG. The sample is made in the form of a plate with two parallel slits 2, perekichki 3-5, transverse slit 6, made in the bridge 4 for the races of the clinching device 7, protrusions 8 and 9, made on the opposite surfaces of the jumper 4. The length and width of the protrusions are selected from the condition so that on: compression yarns (S contact area of the protrusion and proppant, equal to l - -lE-rr Usyzh-FB P exceeds the yield strength of the specimen. This condition ensures plastic deformation of the material in the contact zone and wedging device 7, while loading by a wedging device 7, the working areas of the sample - jumpers 3 and 5 - will reach a predetermined level of tensile stresses.When the sample 1 is kept in an aggressive, especially gas medium, due to the presence of plastic deformation Surface corrosion is practically excluded in the contact zone, since there are no leaks between the protrusions 8 and 9 and the tool 7 and, consequently, there is no access to an aggressive gaseous medium. Intercrystalline. Corrosion of the contact zone is also excluded, since only compressive stresses arise in the zone when pressing the wedge against it. For example, with a totacine sample of 10 m wide side lintel 5 mm and a protrusion length of 10 mm, sign (jf 23 kg / mm NW 38 kg / mm and designating 10 kg / m of contact area F lOgx, and from the condition we determine the width of the protrusion 2. or 4,, 63;: It follows that the width of the protrusion should be chosen equal to 3 mm. The rest of the sample sizes are chosen from design considerations, and the shape of the projection section is chosen trapezoidal with a smaller trapezium base from the side of the contact zone, proceeding from plastically deforming only that the part of the protrusion that is directly adjacent to the contact zone. Claims A sample for testing metals for corrosion under stress, made in the form of a plate of test material with two longitudinal slits, in the middle of one of the bridges is filled with a transverse slit for: a wedge fitting, about 20 mm, and that, in order to increase the test accuracy, the transverse slot is made in the middle bridge, and on the opposite surfaces of the bridge, protrusions are formed symmetrical about the longitudinal and transverse axes of the sample a cyanoid section, the area F of the smaller base of each of which is chosen from the condition. where FP is the total cross-sectional area of the side access points; p is a predetermined level of normal stresses in the side bridges; (JJJ - respectively, the yield strength and tensile strength of the sample material. Sources of information taken into account during the examination 1. Rosenfeld I.L. and Zhigalova KA Accelerated methods of corrosion testing of metals. M., Metallurgi, 1966, p. 289 . 2. USSR author's certificate number 458733, cl. G 01 N 1/28, 1972 (prototype). A IL l / J Figg