Gladkov A. Peculiarities of electron-beam skull melting of Zr-1 Nb alloy and development of tube billets production technology

Dissertation is devoted to investigation of electron-beam melting process of Zr-1 Nb alloy at electromagnetic stirring of melt in the skull crucible with the using zirconium of calcium-thermal reduction, and crystallization processes of this alloy in copper moulds, including external influences on the crystallizable melt. The experimental methods of researches conduction; the standard methods of electrical quantity dimensions; electron, optical microscopy and transmission electron microscopy of thin foils; ultrasonic testing were used at the work. In the result of investigations were determined that the physics-mechanical properties of the Zr-1 Nb alloy which conditioned by technical requirements are achieve by time-thermal treatment of melt on the finish stage of melting with specific power of heating in the focal spot (4,5-5,0)·10^8 W/m^2 and multiplicity of high-temperature treatment 6-7 times. Imposition of the electromagnetic field on melt in the mould is providing to even distribution of elements, structure refinement and increase of alloy mechanical properties. The new technologies of tube billets production from Zr-1 Nb alloy with the using of electron-beam skull melting are developed. Technologies passed experimental approbation at PTIMA NAS of Ukraine and industrial approbation at SSPP "Zirconium".