15-5 PH is a chromium-nickel-copper precipitation-hardening stainless steel developed to provide high mechanical strength, good corrosion resistance and excellent toughness. Its martensitic structure develops high strength through solution treatment followed by controlled aging.

Compared with many conventional precipitation-hardening stainless steels, 15-5 PH is known for good transverse toughness and relatively uniform mechanical properties, making it particularly suitable for large forgings and highly stressed precision components.

Copper provides the primary precipitation-hardening response, while niobium contributes to strengthening and metallurgical stability. Different aging treatments can be selected to achieve the required balance between strength, hardness, ductility and toughness.

15-5 PH is widely used in aerospace, chemical processing and precision engineering. Typical components include aircraft fittings, shafts, fasteners, valves, gears, pump parts, forged rings and other highly loaded structural components.