As early as 1930, the United States studied high chromium cast iron. Due to the high content of chromium, on the one hand, chromium is easy to combine with carbon during cupola smelting, making the carbon content difficult to control; On the other hand, because chromium is easily oxidized and burned in the oxidation zone of cupola, the yield of chromium is very low. Therefore, only after World War II, with the large-scale use of electric furnace, high chromium cast iron has been greatly developed and applied.
When the addition of chromium reaches 12% and the chromium carbon ratio reaches a certain value, the law of iron and carbon combination changes during solidification. The morphology and structure of eutectic carbide changes from continuous network m3c type to disconnected and isolated M7C3 type, and its hardness increases greatly. The Vickers hardness of the original m3c type carbide is 840-1100hv, while the hardness of M7C3 type carbide increases to 1300-1500hv after transformation, The change of carbide composition and morphology improves the wear resistance and directivity of high chromium cast iron at the same time, so high chromium cast iron has been considered as an ideal wear-resistant material since its inception. As early as the early 1970s, Chinese scholars conducted in-depth research on the application of high chromium cast iron in wear-resistant castings. At present, it has been widely used in metallurgy, mining, building materials, electric power, transportation, machinery and other fields, especially in mining, building materials and electric ball mill, and achieved good economic benefits.
High chromium cast iron is divided into hypoeutectic and hypereutectic according to the content of carbon and chromium. At present, hypoeutectic high chromium cast iron is mostly used in actual production. The eutectic carbides of hypoeutectic high chromium cast iron are distributed in isolated strip and broken network. Therefore, hypoeutectic high chromium cast iron has high wear resistance and relatively good directivity. It can be applied to the production of parts and components under certain impact conditions, such as plate hammer of impact crusher, lining plate of ball mill, grinding ball and overflow parts of slurry pump. Compared with hypoeutectic high chromium cast iron, hypereutectic high chromium cast iron has higher carbon and chromium content, significantly increased carbide volume fraction and unparalleled high wear resistance. However, increasing carbide volume fraction is a double-edged sword. In particular, there are a large number of primary phase carbides in hypereutectic high chromium cast iron, which are coarse and have very low toughness, As a result, the overall toughness of hypereutectic high chromium cast iron decreases sharply, cracks are easy to appear in the process of casting and heat treatment, and the scrap rate of castings is increased.