Abstract
The purpose of this study was to evaluate the refining procedure during consumable arc remelting in a 2000-A laboratory-scale furnace. Electrodes used forremelting were airmelted and cast ingots of Fe-Cr alloys and commercial steels AISI-304.
The resultes obtained were as follows:
(1) The carbon in alloys acted as a powerful deoxidizer in molten pool by C-0 reaction under the reduced pressure. It was presumed that the flotation of inclusions contributed to the deoxidation.
(2) The residual nitrogen content in a vacuum-arc-melted ingot was proportional to the initial nitrogen content in electrodes used.
(3) The removal of high vapor pressure impurities such as Pb, Sn, Cu by vaporization in vacuum arc melting were not done so successfully as in vacuum-induction-melting process.
(4) Arc melting in Ar and N2 atmospheres was also carried out with N-155 electrodes, that contained 0.20% nitrogen as an alloying elements, could be remelted successfully without any trouble in a 1/4 to 1 atm Ar-gas chamber. On the other hand, inarc melting of AISI-304 in N2 gas atmosphere, an extremely high-arc voltage was observed and there was a remarkable nitrogen absorption up to 025%.
(5) Melting current extremely influenced the macrostructure. Highercurrent was apt to cause a coarse dendritic structure. Lower current, however, caused a worse ingot surface.
