Comparative erosion–corrosion and electrochemical studies of Ni austenitic cast iron in acidic slurry medium

Abstract

Laboratory experiments were conducted on the erosion-corrosion resistance of four groups of austenitic cast iron with different nickel contents under different acidic slurry conditions. The experiments involved measuring weight loss, examining corrosion morphology as well as X-ray diffraction analysis and electrochemical techniques. While the results showed little erosioncorrosion in a base sand particles environment, erosion-corrosion increased progressively with additions of HCl solution. With the presence of H z , intergranular corrosion and pitting attacks were centred at the boundaries of graphite flakes and alloy carbides. The electrochemical tests showed that the enrichment of nickel and copper in low Ni austenite cast iron can increase the corrosion potential to some extent. As a result, the low Ni cast iron in which Ni content is 8?36 wt-%, and Mn content is 6?57 wt-% exhibited better corrosion resistance than other low Ni cast irons and demonstrated comparable performance with high Ni austenite cast iron.

On a multiphysics approach to modelling the erosion–enhanced corrosion of low–alloy carbon steel in chloride containing environments

“…The research phase on identifying the mechanisms of E-C synergy is an on-going challenge [49], because of the high number of individual processes. These processes can be summarized by a semi-empirical model [50][51][52] that would relate the previously cited parameters with one or more of the following mechanisms: damage of the passive film by the erodent [53,54], strain hardening of the target [55][56][57][58], surface deformation due to erosion-induced pitting [59], the effect of erosion increasing the mass transfer coefficient hence erosion-corrosion rate erosion [60,61], enhancement of wear due to micro-galvanic corrosion between metallic phases [10] or local anodic/cathodic sites [58], influence of corrosion on the mechanical properties of the target material [36,62], the enhancement of wear by oxide layer formation [63,64], enhancement of wear due to intergranular corrosion [65,66], weakening of eroded metallic flakes/lips on the metal surface due to localized corrosion [57]. However, quantification of all these individual mechanisms for a given alloy/slurry system presents some challenges in practice, and hence, a method for predicting erosion-corrosion performance of an alloy employed in a slurry pipeline based on laboratory data remains to be solved [67].…”