2003 Volume 75 Issue 9 Pages 605-611
Nowadays, spheroidal graphite cast iron is widely used for metal tubes buried under ground or soil and structural materials. However, a kind of special soil called marine clay may acidify in such uses, causing corrosion of the metal tubes and structural materials. This research considered the effects of pH on the corrosion behavior of spheroidal graphite cast iron in simulated groundwater using polarization curve and immersing test. The results showed that while pH is 3.5 or less in the immersing experiment, the corrosion rate increases markedly. Thus, the following two factors can be considered as the reason why spheroidal graphite cast iron generates extensive corrosion in acid solution. One reason is the pearlite colony boundary where phosphorous and sulfur segregate dissolves intensely preferentially, and the other is spheroidal graphite and cementite in pearlite promote hydrogen evolution reaction.
