Killed steel is primarily associated with which element?

Killed steel is primarily associated with silicon because silicon is added to steel during the melting process to deoxidize it. The term "killed" refers to the steel being fully saturated with deoxidizers like silicon and possibly manganese, which minimizes the formation of gas bubbles and porosity within the steel as it solidifies. This results in a more uniform and stable microstructure, enhancing the material properties such as strength and ductility.

The addition of silicon acts as a deoxidizer by forming silicates, which combine with any residue of oxygen in the steel, allowing for a refined steel quality. This process is crucial in producing killed steel for applications that demand excellent mechanical properties and predictability in performance.

While manganese is also used to improve steel properties and can aid in deoxidation, it is more commonly associated with the overall improvement of strength and hardness in steels rather than being the primary element linked to the "killed" process. The other elements, phosphorous and sulfur, are typically considered undesirable impurities that can lead to embrittlement and reduced ductility in steel when present in high amounts.