Panchenko S. Control of structure formation processes and complex corrosion properties improvement of pipes made of ferritic-austenitic steels

TResearch subject: processes of structure formation during working and heat treatment of tubes of Cr-Ni-Mo ferritic-austenitic steels. Research objective: improvement of corrosion and mechanical properties of tubes made of Cr-Ni-Mo ferritic-austenitic steels thru formation of a most favorable metal structure during metal forming and heat treatment of tubes in the processes of their production. Methodology: light quantitative and qualitative metallography, scanning electron microscopy, diffraction of back-scattered electrons, energy dispersive X-ray analysis,corrosion and mechanical property tests.The quantitative relationship between the structure (a content of special grain boundaries in the concept of coincident site lattice and phase composition) and corrosion resistance of the tubes Cr-Ni-Mo duplex ferritic-austenitic steel. Has been studied at the PJSC "SPYU" a new mode of double quenching 1150...1200+1050С has been developed and implemented and fabrication of hot and cold rolled tubes of ferritic-austenitic steels, based on the principles of grain-boundary engineering help create the structure containing 75% special low-energy grain boundaries in austenitic-phase; ratio phases of 1:1 and the absence sigma-phase particles and a significant increase of the pipes corrosion and mechanical properties. The technology for the manufacture of pipes made of ferritic-austenitic steels, is based on the principles of grain boundary engineering. It includes hot or cold deformation with a high degree in the manufacture of tubes, respectively, and a double quenching and provides more favorable evidence-based steel structure and high complex corrosion and mechanical properties of pipes. The kinetics of formation and the range is the most dangerous temperatures occurrence ?-phase structure of the tubes Cr-Ni-Mo duplex steels. The non-destructive method for quantitative evaluation of intermetallic phases and methods of testing tubes for resistance to pitting corrosion and stress corrosion cracking has been developed and implemented.Field of application: metallurgy, pipe and tube industry, chemical industry, building and architecture.