VACUUM MELTING AND POURING ON NICKEL BASE-ALLOYS

Melting and pouring of Ni base alloys in vacuum up to 10 to the -5th power mm Hg improved their mechanical properties, namely: toughness by 80%, durability by 30%, area reduction (at room temperature) by 50%, and elongation y 30%. In addition, a perfectly pure allo was produced, showing no film formation. In vacuum melted heat-resistant alloys TiC particles were very fine and uniformly distributed throughout the grain pattern. The volatilization rate of the alloying component increased slightly as the vacu m level was raised from 0.1 to 10 to the -5th power mm Hg. T HE AMOUNT OF VOLATILIZED CHROMIUM INCREASED BY ).%, that of Al by 2.5%, while the C content remained practically unchanged. In vacuum melting and pouring of heatresistant alloys the gas content decreased sharply. The lowering of the O content depended on the vacuum level as well as on the intensity of interaction between the liquid alloy and the material of crucibles. The H and N degassing of the alloy reached a maximum at 0.001 mm Hg. (Author)