It is well-known that the properties of Cu-Pb alloy are very unstable by the cooling velocity. In this report, the effect of a small amount of Sn on the stability of casting has been investigated by means of the microstructure, hardness and oil-dipping test. The results obtained may be summarized as follows :
By adding 0.15∼0.30% of Sn the stability of casting is markedly improved, but this effect is little when the alloy contains a large amount of Pb. If Sn is added as much as shown above, the alloy shows a granular or network-like dendritic structure. The degree of structure difference caused by cooling velocity is generally smaller than that in which there is the no addition of Sn. The hardness of the alloy is not effected by the addition of Sn below 0.15%, but it is rapidly increased when over 0.3% of Sn is added.
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