Most of the adamite rolls are produced by static integral casting. In 2002, a centrifugal composite semi-steel backup roll was developed and trial-produced in China. The outer layer of the roll body is made of semi-steel material, and the body and neck of the roll are made of ductile iron. Hot rolled medium wide steel finishing mill. The semi-steel roller ring is produced by centrifugal casting. The outer layer of the roller ring is made of high-carbon semi-steel, and the inner layer of the roller ring is made of graphite steel or ductile iron. On the high-speed rotating centrifuge, two kinds of iron and steel water of different materials are poured respectively. Composite casting.
Adamite rolls must be subjected to high-temperature diffusion annealing treatment: chromium and carbon are important elements to form carbides of semi-steel rolls and thus are also important elements to improve the wear resistance of rolls. However, since the solidification of the roll is a non-equilibrium process, the crystallization of the solid solution from the molten steel is a segregation crystallization process, so there is serious chromium segregation in the as-cast microstructure of the adamite roll. The austenite grain boundary is a chromium-rich area and a carbon-rich area, where secondary carbides will precipitate and form a network, which greatly damages the microstructure and properties of the roll. Therefore, in order to eliminate the chromium segregation caused by the solidification segregation of the roll, it is necessary to carry out a high-temperature diffusion annealing treatment on the adamite roll.
The influence of non-metallic inclusions on the microstructure of adamite rolls: When there are a large number of high-melting non-metallic inclusions in the molten steel, it is easy to form a pseudo-eutectic carbide core, and the eutectic or pseudo-eutectic carbides precipitated during the solidification process are preferred It grows up, and it is easy to form large carbides. The huge cementite is easy to become the occurrence point of thermal cracking and accelerates the expansion of cracks. The existence of non-metallic inclusions will make the fracture toughness value and The plasticity index decrease. Therefore, the adamite roll generally requires the total amount of non-metallic inclusions to be controlled below 0.05%.
