Investigation into the refining processes of nickel base alloys during vacuum plasma arc remelting

Regularities in refining of the nickel base alloys (nichrome, EhI- 437 BU and EhI-617) during vacuum plasma-arc remelting (VPAR) at the pressure of 1x10-3-0.5 Totrr are studied. The total metal evaporation losses during VPAR not higher than 1-3%, which is considerably lowep than during the electron-beam remelting (5-7%). Investigation into the effect of the main technological parameters on the change in chemical composition shows that the remelting at lower pressure permits to keep the alloying elements in the metal, which have higher vapour elasticity in the range, which meet the requirements of technical conditions. Remelting at lower pressure is highly effective at the refining processes of nickel base alloys from admixtures of non-ferrous metals and gases: bismuth and lead content decrease by 90%, antimony content- by 70%, oxygen content- by 50% and nitrogen content- by 75%. Use of vacuum plasma are remelting is perspective for improving tthe quality of nickel base alloys