17-4PH Stainless Steel Composition & Precipitation Hardening Properties

17-4PH is a precipitation hardening martensitic stainless steel specified in ASTM A564 and GB/T 4237, containing approximately 15–17.5% chromium, 3–5% nickel, copper, and niobium. Through a low-temperature aging treatment after solution annealing, the grade achieves very high strength while maintaining moderate corrosion resistance superior to standard 400-series martensitic grades.

Depending on the selected aging condition, the grade provides yield strength from approximately 725 MPa up to 1170 MPa, allowing designers to match strength and toughness requirements for individual components. It is commonly used in pump shafts, valve parts, turbine blades, aerospace fittings, and high-load mechanical components.

17-4PH is available as plates, bars, and forgings. It is widely used in aerospace structures, oilfield equipment, power generation, and precision machinery where high strength and reliable corrosion service combine in one grade.