The Nitrogen Absorption of Arc-Melted Fe-Cr and Fe-Ni Alloys

Fe-Cr and Fe-Ni alloys were melted by tungsten arc-melting under argon-nitrogen gas mixture atmospheres with various melting conditions in order to study effects of chromium and nickel on the nitrogen absorption of arc-melted iron. In Fe-Cr alloys with chromium more than 8%, the nitrogen content decreases with increasing the arc current. In Fe-Cr alloys with chromium less than 5.6% and Fe-Ni alloys, the nitrogen content increases slightly with the arc current. In all alloys, the nitrogen content increases with the arc-melting time and then reaches the saturated value which increases with the nitrogen partial pressure of the atmosphere, but does not obey the Sieverts’ law. The nitrogen content of arc-melted iron increases remarkably with the chromium content, while decreases slightly with increasing the nickel content. The nitrogen absorption of the arc-melted alloys was discussed thermodynamically with measured temperatures of the molten alloys during arc-melting.