Abstract
It is a well-known fact that cold blast charcoal pig iron has the far more superior qualities than that of coke pig iron, but is not yet clear that causes. The author studied the relation between the strength and the melting con, ditions, and finally determined the nitrogen content in the above test pieces.
The nitrogen obtained from these test pieces are, in cold blast charcoal pig 0.0008-0.0010%, in hot blast charcoal pig 0.0012-0.0020%, in electric arc furnace iron 0.0015-0.0035%, in. coke pig 0.0017-0.0025%, The strength of cast iron is almost inverse oroportional to the nitrogen content in the materials.
From these facts, the author concludes that the small contents of the nitrogen in cold blast charcoal pig iron is one of the main couses giving rise to its superior qualities.
