17-4PH is a martensitic precipitation-hardening stainless steel. Its core feature is achieving a balance between high strength and moderate corrosion resistance through solution annealing + aging heat treatment, making it a commonly used high-strength stainless steel material in industrial applications.
Chemical composition:It mainly contains 15–17.5% chromium, 3–5% nickel and 3–5% copper, with an addition of 0.15–0.45% niobium and a carbon content of less than 0.07%. Copper and niobium are the key elements enabling precipitation hardening.
Microstructure:It exhibits a martensitic structure at room temperature. After solution annealing, it forms a supersaturated solid solution; subsequent aging treatment precipitates fine copper-based precipitates, which contributes to strength enhancement.
Core properties:High strength (tensile strength of 1000–1400 MPa), moderate corrosion resistance (superior to conventional martensitic steels but slightly inferior to 304 stainless steel), good machinability and weldability, as well as stable toughness at both room and low temperatures.
Application scenarios
Mechanical manufacturing: High-strength structural components such as bolts, gears and shafts.
Aerospace: Aircraft landing gear components and engine parts.
Petrochemical industry: Corrosion-resistant and high-strength components including high-pressure valves, flanges and pump bodies.
Medical devices: Surgical instruments and certain implants (subject to biocompatibility requirements).