Phosphorus has a large segregation in steel. In the high phosphorus content, the plasticity and toughness are greatly reduced, especially at low temperatures, the "cold brittleness" is less obvious. Generally, this harmful effect of phosphorus is enhanced as the content of C, N, and O in the steel increases. Phosphorus also has an adverse effect on the weldability of steel.

Briefly describe the characteristics and mineral composition of the middle slag during blowing.

In the middle of the blowing process [C], [O] is intense, and the slag is prone to "back to dry". Its characteristics are high alkalinity and low ferrous oxide content. The mineral composition of the slag is: mainly dicalcium silicate and dicalcium silicate. When the lime is added, there is more free CaO. The higher the alkalinity, the larger the amount of dicalcium silicate, and the more free CaO, which is detrimental to the smelting effect.