Phosphorus bronze (PB4) is an alloy composed of copper and tin, typically with 0.5-1% phosphorus added. This strong, corrosion-resistant material has various applications across various industries due to its durability, excellent electrical conductivity and low contact resistance. Examples are electrical component contacts, bellows valves for steam turbines and organ pipes. PB4 has also been used in household items such as doorknobs and locks for centuries because of the metal's superior hardness compared to other materials.

Phosphorus Bronze PB4 is a type of copper alloy with improved strength and hardness due to adding 1-2% phosphorus. It has excellent corrosion resistance in freshwater, salt water, organic chemicals, and certain gases. This makes it well-suited for electrical connectors and valve components requiring high pressure and chemical resistance. Additionally, its low electrical conductivity makes it suitable for springs for electrical appliances such as switches or relays. The high initial modulus of elasticity also allows use in bearing components where quiet operation is desired.