Computational Studies on Structure and Mechanical Properties of Carbides in HCCIs

Abstract

High Chromium Cast Irons (HCCIs) are widely used in mineral processing, slurry pumping and manufacturing processes, where high resistance to erosion and synergetic erosion-corrosion is required. The excellent performance of HCCIs results from their microstructure, which consists of hard carbides (mainly in hypereutectic HCCI) and ferrous matrix (austenite or martensite ). The matrix helps absorb impact force and enhance toughness of the material, while the hard carbides play a crucial role in withstanding the wearing stress. Due to different processing treatments and chemical compositions, the morphology and mechanical properties of carbides can vary significantly, which affects HCCIs' wear performance. In this study, the effect of core-shell structured carbides on HCCIs' wear performance and the effect of Cr content on M7C3 carbides' mechanical properties are studied by different simulation methods. C++ programming based MSDM method is used to study and optimize the core-shell structured carbides, which have been proved beneficial to HCCIs' wear resistance. By measuring local properties, including Young’s modulus and electron work functions, and conducting first-principles calculations for individual phases, HCCIs' erosion-corrosion performance in slurry are better understood. At last, the correlation between Young's modulus and electron work function is explained by first-principles calculation from an electronic view.