SU920442A1 - Method of determination material destruction viscosity - Google Patents

Description

(54) METHOD FOR DETERMINING THE VISCOSITY OF DESTRUCTION OF MATERIAL

one

The invention relates to a test (of materials and structural elements, in particular, to methods for determining the fracture toughness of a material.

A known method for determining the fracture toughness of a material is that the notched specimen is loaded in a corrosive environment prior to fracture, and the fracture formation parameters are determined and, therefore, the fracture toughness of the material 1 is judged.

In the known method, a single loading of the specimen is carried out, therefore, the disadvantage of the method is little information about the properties of the material.

The closest in technical essence and the achieved result to the invention is the method of determining the fracture toughness of a material, which consists in the fact that in a sample of a material with a notch a fatigue crack is grown from the top of the notch under cyclic loading,

load the specimen before the crack jumps, unload the specimen, re-grow the fatigue crack, continue loading the specimen until it collapses, measure the increase in the crack length corresponding to each stage of static loading, and judge the fracture toughness 2.

The disadvantage of the known method is that it does not contain information on the effect of activation of stress corrosion cracking on the fracture toughness.

The purpose of the invention is to expand the informativity of the method by taking into account the effect of corrosion cracking.

Claims (1)

This goal is achieved by the fact that when growing fatigue cracks, the sample is placed in a corrosive environment, the changing shape of the cyclic load is chosen sawtooth, and its maximum value is equal to the static load of the next load step. The drawing shows a graph of the load applied to the specimen. The method is carried out as follows. A sample of the material with a notch to determine the fracture toughness is placed in a container with a corpusive medium and loaded. The corrosive medium is poured into the container so that the working part of the sample and the notch, from the top of which the crack develops, are in a corrosive environment. The loads are performed first on this cyclical load with a pylorb form, and then with a static load on the stage of the whole. The cyclic load at stage ct6 serves to grow the fatigue crack from the notch tip. Subsequent static loads on the stage are all applied before the jump of the tracine. Static load can be constant in magnitude to determine long-term strength or increase to determine short-term strength. Figure 1 shows the static static load. After the crack jumps, the sample is unloaded and again subjected to cyclic loading at the cd stage, which serves to grow a fatigue crack from the top of the crack that develops under static loading. The maximum value of the cyclic load is set equal to the value of the static load of the next loading stage (stage c / e). Then, static loading is repeated for a period of time de, the fatigue crack again grows in step ef, and so the loading of the sample is continued until the specimen is destroyed. At. the test measures the crack length increment corresponding to each stage of static loading 6c, / €, etc., and judging the fracture toughness. The method allows to expand the information content of the method by taking into account the activation of corrosion cracking of the material. The invention of the method for determining the fracture toughness of a material, is that in a notched sample of material a fatigue crack is grown from the top of the notch under cyclic loading, the sample is statically loaded before the crack is jumped, the sample is unloaded, the fatigue crack is re-grown, the sample is continued to load, the crack length increment corresponding to each stage of static loading is measured and judged on the fracture toughness, characterized in that, with the aim of expanding informatively method by taking into account the effect of corrosion cracking. Growing a fatigue crack, the sample is placed in a corrosive environment, the shape of the changing l cyclic load is chosen sawtooth, and its maximum value is equal to the value of the static load of the next stage of loading. Sources of information taken into account in the examination 1. New methods for assessing the resistance of materials to brittle fracture, ed. Yu.N. Worker, M., Mir, 1972, p. 230g232. 2, Kudr seam V.G. et al. Destruction toughness of aluminum alloys, M., Metallurgists, 1976, p. 65-68 (prototype). Bark Cyclic / ff ffint // a / ti / e fn / fea UH i Shania source tsmoAvnoi Rrem