Study of Technology for Ultrafine-Grained Materials for Usage as Materials in Nuclear Power

Abstract

Nuclear power is associated with great environmental risks. In many cases, the problem of accidents of nuclear power plants is related to the use of materials that do not fully meet the following requirements: high corrosion resistance; high temperature resistance; creep resistance; fracture toughness; stability of structure and properties under irradiation. Therefore, studies aimed at finding materials that can withstand long-term loads at high temperatures, aggressive environment and gradual structural degradation under the influence of radiation are relevant. One of the structural materials, which has high resistance to radiation, is austenitic stainless steel. And one of the ways to increase the radiation resistance of parts made of this steel grade is to grind its microstructure to ultra-fine-grained state. Such structures provide a combination of a high level of strength characteristics with high plasticity, which distinguishes such materials from their coarse-grained counterparts. Also, numerous grain boundaries serve as runoff surfaces for radiation defects, preserving the structure, which causes their increased radiation resistance. From all methods for producing sub-ultra-finegrained materials the most promising is the severe plastic deformation (SPD), which can be implemented in the metal in various ways, including radial-shear rolling. This paper presents the results of studies of the process of radial-shear rolling on the mill SVP-08 and its effect on the microstructure and properties of austenitic stainless steel. During the study, bars with a diameter of 13 mm from AISI-321 steel with a grain size of 300-600 nm were obtained, while the mechanical properties increased more than 2 times compared to the initial values.