Fracture toughness degradation of cast iron due to corrosive mediums

Abstract

Corrosion induced degradation of fracture toughness in buried cast iron pipes is a serious concern for structural integrity and smooth operation of buried pipes. External corrosion of pipes is fundamentally governed by the corrosivity of soil which may vary depending on the type of soil and its specific properties. While the corrosion assessments of pipes buried in soil can provide realistic behaviour, the investigations of pipe corrosion in simulated soil solutions are becoming popular due to simplicity. Limited studies are reported in the literature using simulated soil solution for determining the effect of corrosion on the fracture toughness of cast iron specimens. However, it is important to evaluate the outcomes based on the solutions benchmarking against the corrosion from the realistic soil environment. This study investigates the corrosion of cast iron specimens in both the acidic soils and the simulated soil solutions of the same varying pH for 365 days. The fracture toughness testing of the corroded specimens taken out from both the real and simulated soil solutions was performed at 180 and 365 days, respectively. The fracture toughness (KQ) values of the corroded specimens of the two soil mediums were compared and correlated statistically. Moreover, relations for the variation in KQ of specimens as a function of corrosion rates, and pH with time were developed for soil and simulated soil solution. The findings of this research have practical applications for the predictions of the service life of buried cast iron pipes.