Effect of pearlite on the vibration-fracture behavior of spheroidal graphite cast irons under resonant conditions

This investigation examined the effect of pearlite on the vibration-fracture behavior of spheroidal graphite (SG) cast irons under resonant conditions. The experimental materials can be divided into four groups, according to their pearlite content. They are (1) a fully pearlitic matrix, (2) a bull's-eye structure, (3) a colony-type pearlitic structure, and (4) a fully ferritic matrix. Experimental results indicated that the variation of pearlite content significantly affects the initial deflection amplitude. Increasing the amount of pearlite in the matrix leads to a lower logarithmic decrement and, thus, reduces the deflection amplitude. Moreover, the distribution and amount of pearlite considerably influence the crack-propagation mode. The specimen with a bull's-eye structure exhibits the highest resonant-vibration fracture resistance. This can be attributed to the lower initial deflection amplitude caused by the ferrite rim around graphite particles and the better crack-propagation resistance of the surrounding pearlite.