Rimmed steel is a type of low-carbon steel that has a clean surface and is easily bendable.
When steel is normally made, it is deoxidized completely; with rimmed steel, the steel is only partially deoxidized, which allows a rim to form. This rim is almost completely free of other elements and is mostly iron.
There is less carbon, so this steel is softer than other types, which makes it ideal for cold-bending and rolling applications. Of all the low-carbon steels, rimmed steel is one of the most common.
Most rimmed steels contain less than 0.1% carbon. Rimmed steel has an excellent, defect-free surface which gives it advantages over other types of steel. Steel sheets and plates are produced from rimmed steel.
It is characterized by low cost, good surface quality and deep drawing performance, but large composition segregation, uneven quality, poor corrosion resistance and mechanical strength. This type of steel is used in large quantities for the rolling of steel and steel sheets of plain carbon steel.
Killed steel refers to steel that is completely deoxidized. When pouring, the molten steel is killed and there is no boiling phenomenon. These types of steel are characterized by less segregation of components and uniform quality, but at a higher cost. Alloy steel and high-quality carbon steel are generally killed steel.
Semi-killed steel refers to a type of metal alloy compound of iron and carbon that has been partially deoxidized with minimal gas release during solidification.
Semi-killed steel presents a high degree of homogeneity on the molecular level. It also has minimal degrees of gas porosity, making it ideal for heat treatment. Generally, more gas is evolved in semi-killed steel than in killed steel.
Semi-killed steel refers to steel with a degree of deoxidation between rimmed steel and killed steel. The boiling phenomenon is weaker than that of rimmed steel during pouring. The quality and cost of steel is also between rimmed steel and killed steel. However, its production is difficult to control, so these types of steel does not account for a large proportion of steel production.