What treatment do steels described as "killed" undergo during processing?

Killed steels undergo a specific treatment involving the addition of deoxidizers during the steelmaking process to improve their quality and mechanical properties. The term "killed" refers to the method used to eliminate excess oxygen from the steel. This is typically achieved by adding strong deoxidizing agents, such as aluminum, during the melt. By using such materials, the oxygen is bound up and removed from the steel, which prevents the formation of gas bubbles and results in a more uniform microstructure.

This process enhances the steel's properties by reducing porosity and excessive shrinkage, thus making the final product more robust and free from defects that could compromise its integrity. The practice of killing steels is important for applications requiring high-quality and reliable structural components.

High temperatures for extended periods and the addition of silicon alone do not specifically designate the killed treatment; they may be involved in other steelmaking processes. Cooling in liquid nitrogen, while it can enhance certain properties of steel, is not part of the killed treatment process.