ALLOY CONTAMINATION

If the alloy becomes contaminated with other metals or chemical compounds, cracks may occur. Sources of contamination may be aluminum or steel from drying pans, chips of refractory from furnace covers, or fluxes that are oxidizers, which are meant for refining. Gas furnaces that may be too oxygenated will also cause reactions with the alloy, forcing the silicon out of the molten metal. Usually discoloration of the surface will appear in addition to the cracking. Abnormal weight-loss is another symptom of oxidizing the alloy.