Characteristics of chilled cast iron and wear-resistant alloy cast iron

Chilled cast iron and wear-resistant alloy cast iron are commonly used wear-resistant materials in production. Chilled cast iron, also known as chilled iron, is obtained by placing a chill iron in the mold to accelerate the cooling rate of the casting. The typical chemical composition of chilled cast iron is: C content of 3% to 3.5%, Si content of 0.5% to 0.7%, Mn content of 0.5% to 0.7%, P content less than 0.4%, and S content less than 0.07%. The characteristic of chilled cast iron is that the surface part undergoes white cast, greatly improving hardness and wear resistance, while the interior still maintains a gray cast structure to prevent overall embrittlement. The hardness of the chilled surface layer reaches around HRC60, and calender rollers are an example.
Chilled nickel-chromium cast iron is also an example of this. Chilled nickel-chromium cast iron has a Ni content of 4% and a Cr content of 1.1%. Ni refines pearlite and graphite, increasing the strength and wear resistance of the cast iron. Adding Ni can also improve thermal strength. The hardness of chilled nickel-chromium cast iron can reach HRC60, and it is commonly used to manufacture rolling rolls.
High chromium cast iron is a high-temperature wear-resistant cast iron, with typical composition of 22% to 25% Cr, 1.2% Si, and 0.3% to 0.75% Mn. The addition of Cr enhances the wear resistance of the cast iron, as Cr forms a dense protective film, Cr2O3, on the surface of the casting. The addition of Cr also generates carbides, which increases the hardness and strength of the cast iron. High chromium cast iron can be used to manufacture wear-resistant components that operate at temperatures above 800°C.
The mud pump used in drilling is made of wear-resistant alloy cast iron Crl5Mo3, with a hardness of HRC62, making it one of the most difficult metal materials to machine.