Tin is a powerful pearlite promoter and is exclusively used for the production of pearlitic ductile iron, especially when producing as-cast iron. If the melt is pure enough regarding trace or detrimental elements, the pearlite promoting influence of tin is about thirteen times that of copper by the addition of 0.1% of tin. Tin is undesirable for a ferritic ductile iron generated by heat treatment, because the pearlite forced by tin is very stable and can only be decomposed very slowly.
Tin, in connection with a high amount of detrimental elements, leads to graphite degeneration to a great extent and with it to a drastic decrease of tensile strength, 0.2% offsetyield strength and, above all, the elongation (figs. 1 and 2).
Structure formation of cast iron