High-alloy materials such as high chromium cast iron and high speed steel have excellent wear resistance under extreme wear conditions. But they consume much expensive chromium, molybdenum, tungsten and other alloying elements too. The hypereutectic high boron alloy has good wear resistance because it contains many high hardness primary borides. But the dimension of primary borides is big. In this paper, the hypereutectic high boron alloy was prepared using sand casting method, and the primary borides were modified by different amount of K / Na modificator. The results show that the primary boride of hypereutectic high boron alloy is Fe2B. K/Na modificator has a significant influence on primary Fe2B. The best grain refinement effect of primary Fe2B is obtained when the amount of K/Na modificator is 0.3%. The refining mechanism of primary Fe2B is that K/Na modificators can not only increase the supercooling degree to improve nucleation rate but attach to the crystal face of fastest growth direction to prevent grain from growing

This article focuses on research into thermal shock fatigue resistance and oxidation resistance of as-cast ferritic nodular iron. The results show that the number of cycles required to crack nodular iron under the action of thermal stress is significantly higher than that of grey cast iron, and the rate at which cracks spread is lower compared with that of grey cast iron. When graphite is transformed from flakes into nodules, its decreased connectivity impedes the flow of oxygen during oxidization, thereby improving its oxidation resistance.

National standard high chromium cast iron contains 26% chromium by weight (Cr26). A new type of Super High Chromium Cast Iron (SHCCI) has been developed with chromium content of about 37% by weight. This paper examines the microstructure of SHCCI using SEM and XRD. The hardness and toughness of SHCCI was studied and the corrosive wear properties of SHCCI were also examined using an MCF-30 type erosion abrasion tester under H3PO4 media. The results show that, the microstructure of SHCCI is composed of M7C3 and M23C6 carbides, martensite matrix and residual austenite matrix. With proportionately greater carbon content, the hardness of SHCCI will first increase and then decrease, while the toughness and corrosive wear properties will decrease gradually SHCCI’s corrosive wear performance was significantly better than that of Cr26 cast iron. The maximum wear capacity of SHCCI is three times higher than that of Cr26 cast iron.

The corrosion property of high chromium cast iron was test under different phosphoric acid medium concentration. On the base of experimental data, the binary equation model of corrosion weight loss (W) versus phosphoric acid concentration and corrosion time (c, t) was built using multiple regression analysis, which can predict corrosion property of high chromium cast iron effectively. The prediction results show that the corrosion weight loss rises lineally with increasing corrosion time, and the corrosion rate rises quadratically with increasing phosphoric acid concentration. The corrosion failure mechanism is that chromium composite carbides (M7C3) stand out of matrixes surface after the matrixes composed of martensite and austenite are corroded firstly, then the M7C3 carbides drop out of matrixes when the matrixes can not wrap M7C3 carbides, resulting gradual corrosion of high chromium cast iron. The prediction values have sufficiently mined the basic domain knowledge of corrosion process of high chromium cast iron under phosphoric acid medium. Therefore, a new way of predicting corrosion property according to corrosion conditions was provided by the authors.