Phosphorus
Phosphorus can be either a steel parasite or an alloying element. The harmful effect is predominant, as it can lead to embrittlement and increases the cold brittleness and tendency to brittle fracture. For this reason, phosphorus is largely removed from steel alloys in most cases.
As an alloying element, phosphorus only develops its effect in low-alloy steel with a carbon content of about 0.1%. Phosphorus then increases strength and also improves corrosion resistance. In austenitic chrome-nickel steels, phosphorus can increase the yield strength.
The effect of phosphorus upon mechanical steel properties:
| Property | Influence | Degree |
|---|---|---|
| Rust resistance | no bearing | 0 |
| Hardness | Improvement | + 1 |
| Strength | Improvement | + 1 |
| Yield strength | Improvement | + 1 |
| Elasticity | no bearing | 0 |
| Heat resistance | no bearing | 0 |
| Carbide formation | no bearing | 0 |
| Wear resistance | no bearing | 0 |
| Nitratability | no bearing | 0 |
| Strain | Decrease | - 1 |
| Reduction of area | Decrease | - 1 |
| Notched Impact Strength | Decrease | - 3 |
| Forgeability | Decrease | - 1 |
| Scaling | no bearing | 0 |
| Machinability | Improvement | + 2 |
Trivia
The German pharmacist Henning Brand discovered phosphorus by chance in 1675. He was convinced that human urine was suitable for gold production because of its yellow colour. He boiled about 50 buckets of urine until he obtained a wax-like mass.
He did not make gold with it, but after a while the mass began to glow. Parts that were brought into the refining air caught fire. Since the production was too expensive, no benefit could be derived from it. In 1774 the German-Swedish pharmacist Scheele was the first to produce phosphorus from bones.