Effect of Phosphorus on Steel Properties
The chemical element p is phosphorus. Phosphorus, atomic number 15, atomic weight 30.973762, has three allotropes: white phosphorus, red phosphorus, and black phosphorus. White phosphorus, also called yellow phosphorus, is a white to yellow waxy solid with a melting point of 44.1°C, a boiling point of 280°C, and a density of 1.82 g/cm3.
P is brought into steel from ores. Generally speaking, phosphorus is also a harmful element. Although phosphorus can increase the strength and hardness of steel, it causes a significant decrease in plasticity and impact toughness. Especially at low temperatures, it makes steel significantly brittle, a phenomenon called "cold brittleness". Cold brittleness deteriorates the cold working and weldability of steel. The higher the phosphorus content, the greater the cold brittleness, so the phosphorus content in steel is strictly controlled. High-grade high-quality steel: P<0.025%; high-quality steel: P<0.04%; ordinary steel: P<0.085%.
P has good solid solution strengthening and cold work hardening effects. It can be used in combination with copper to improve the atmospheric corrosion resistance of low-alloy high-strength steel, but reduces its cold stamping performance. It can be used in combination with sulfur and manganese to improve the machinability and increase recovery. Fire brittleness and cold brittleness sensitivity.
Phosphorus can increase the specific resistance, and can reduce coercive force and eddy current loss because it is easy to coarsen the grain. In terms of magnetic induction, the magnetic induction of steel with high phosphorus content will increase under weak and medium magnetic fields. Thermal processing of P-containing silicon steel It is not difficult, but because it will make silicon steel cold brittle, the content is ≯ 0.15% (such as silicon steel for cold-rolled motors containing P=0.07~0.10%).
Phosphorus is the element with the strongest effect on strengthening ferrite. (The influence of P on the recrystallization temperature and grain growth of silicon steel will be 4 to 5 times greater than that of the same silicon content.)
The above is an analysis chart of the global quantity proportion of phosphorus, for reference only.
Sharing in the next issue: Sulfur/Calcium: Impact on Steel Properties
Share in the next issue: Titanium/vanadium/chromium: influence on steel properties
Looking forward to your attention and return visit.
Search Blog
