Kravchuk R. Determination of mechanical properties of structural steels by indirect methods

The object of study is the determination of the mechanical characteristics of structural steels used in the manufacture of critical equipment elements. The purpose of the work is the development of methods for determining the strength characteristics of structural steels by indirect methods based on the results of small punch test, instrumental indentation and hardness measurements, as well as obtaining new data for a number of materials of critical structural elements by their strength using these methods. Research methods are: experimental and numerical methods for studying the mechanical characteristics of structural steels. Theoretical and practical results are: improved methods for determining the strength characteristics of structural steels by indirect methods based on the results of small punch test, instrumental indentation and hardness measurements. The scientific novelty of the results is: a method has been developed for determining the strength characteristics of structural steels by small punch test using the correlation not from the force parameters of the punching shear diagram, but with the conditional stresses acting in the sample section in the limiting area of its contact with the ball; new correlations have been established to determine strength characteristics based on the results of indentation and Brinell hardness measurements with a tungsten carbide ball in accordance with modern requirements; new data on the mechanical characteristics of critical equipment materials of nuclear power plants, as well as alloyed high-strength steels and their welded joints were obtained using the developed methods. The results of the dissertation work were implemented in solving problems important for the nuclear power industry of Ukraine on assessing the resource and strength of equipment elements of the Rivne NPP and the South-Ukrainian NPP, as well as in the non-destructive testing of the strength characteristics of materials and structures for military purposes. Some results were used in the standard of the G. S. Pisarenko Institute for Problems of Strength of the National Academy of Sciences of Ukraine SOU-56-28-2018 «Metallic materials. Determination of the characteristics of the mechanical properties of structural materials by Brinell hardness and by the instrumented indentation method. Test method». The obtained results can be used to determine the mechanical characteristics of critical equipment materials by indirect methods.