Sidorov

Nitrogen behavior under different thermo-time modes of the melting alloy HA30-VI in the induction furnace was investigated; optimal temperature of melted nitrogen depuration was determined. The negative influence of nitrogen on the formation of parasitic grains with random orientation near the surface of mono-crystal casting was shown. Non-uniform distribution of nitrogen with the height of cast mono-crystals was determined.

The authors study the influence of nitrogen on the form of primary carbides in charge intermediates of alloy GS 30-VI. Metallographic researches of the structure and forms of primary carbides were conducted in initial charge intermediates with various impurity content of nitrogen. It was established that with the increase of nitrogen content from 0,0004-0,0008% to 0,0015-0,0035% carbide morphology acquires a rounded or polyhedral form instead of laminar. The authors present the dependence between the impurity nitrogen content in the heat-resisting alloy and the quality of produced single-crystals. The authors propose a formation mechanism of primary carbides of various morphology during melt solidification.