Study On Maching And Stress Corrosion Of Nuclear Austenitic Stainless Steel

Nuclear grade austenitic stainless steel is an important structural material used in nuclear power equipment,and its stress corrosion cracking(SCC)is one of the main factors causing the failure of components in nuclear facilities.Nuclear grade austenitic stainless steel has good mechanical strength and good corrosion resistance,but in machining can make internal micro organization change influence on the surface of the material physical,chemical,machinery and so on various aspects of performance,therefore,in the high speed cutting process of high temperature and mechanical extrusion can make the material surface hardening,surface residual stress,surface quality changes,which influence the external corrosion resistance of the material.In this paper,the milling force,residual stress and surface microstructure of nuclear austenitic stainless steel were systematically studied and their effects on stress corrosion were investigated.The main research contents are as follows:1?using the single factor method to design high speed milling nuclear grade stainless steel test of Mr Obama's body,to explore the milling parameters on milling force,surface roughness,surface hardening,the influence of the residual stress,explore the milling parameters with nuclear grade austenitic stainless steel milling surface quality between the change rule,in order to get the optimal machining parameters on the surface of the milling.2?The ABAQUSE finite element software was used to establish a two-dimensional model of high-speed milling core grade austenitic stainless steel for simulation.The simulation data of milling parameters on milling force and residual stress distribution on milling surface were obtained,and the experimental verification was carried out as the research object.3?Taking the typical cutting residual stress as the research object,the influence of residual tensile stress and residual compressive stress on the chemical properties of nuclear grade austenitic stainless steel at high temperature and high voltage is analyzed.Samples with the maximum and minimum residual tensile and compressive stresses on the cutting surface were immersed in boiling MgCl₂solution at high temperature and high pressure for 216 hours(9 days)to study the changes of corrosion current and polarization curves during the corrosion process,and to observe the corrosion rate of the samples.The phase generation of the samples before and after corrosion was analyzed,the relationship between the residual stress and the number of corrosion cracks was analyzed,and the influence of cutting parameters on stress corrosion was explored.Based on experimental data,theoretical analysis and finite element simulation,this paper elaborates the change rule of milling force,surface microstructure and surface residual stress of nuclear grade stainless steel in high speed cutting.The formation law of stress corrosion was analyzed and studied by the change of surface characteristics.The research results can improve the efficiency of parts production,optimize milling parameters and improve the theoretical basis of stress corrosion resistance of material surface.