The influence of alloy elements and cooling rate on the as-cast hardness of spheroidal graphite iron was studied for obtaining fundamental knowledge on controlling hardness.
The effects of manganese, copper and tin were compared as alloying elements, and the results showed that the pearlite area ratio of the matrix increases when copper and/or tin is added, and Brinell hardness was also higher.
The results of investigating the relationship between cooling rate before eutectoid transformation (at 1073 K) and Brinell hardness indicated a linear relationship between the logarithm of the cooling rate and the hardness. The difference in hardness according to the cooling rate is considered to be caused by the interlamellar spacing of pearlite and the amount of carbon in the matrix.
