Specification Overview
ASTM A564 is an ASTM International specification covering bars and shapes of age-hardening stainless steels, including the widely used 17-4PH alloy (Type 630, UNS S17400). The specification encompasses hot-finished or cold-finished rounds, squares, hexagons, bar shapes, angles, tees, and channels. These shapes may be produced by hot rolling, extruding, or forging. The nominal composition of 17-4PH — 16% Chromium, 4.0% Nickel, 0.30% Columbium + Tantalum (Cb+Ta), and 4.0% Copper — delivers an exceptional combination of high strength, good corrosion resistance, and excellent mechanical properties that can be further enhanced through precipitation hardening heat treatment.
Per the specification description: "This specification covers bars and shapes of age-hardening stainless steels. Hot-finished or cold-finished rounds, squares, hexagons, bar shapes, angles, tees, and channels are included. These shapes may be produced by hot rolling, extruding, or forging. Type 631 and 632 stainless steels contain a large amount of ferrite in the microstructure and can have low ductility in forgings and large diameter bars. Material of types other than XM-16, XM-25, and Type 630 shall be furnished in the solution-annealed condition, or in the equalized and oven-tempered condition. Types 630, XM-16, and XM-25 may be furnished in the solution-annealed or age-hardened condition. Type UNS S46910 shall be furnished in solution annealed, cold-worked or aged-hardened condition. Shapes may be subjected to either Class A or Class C preparation for removal of visible surface imperfections. The material shall be subjected to tension, impact, and hardness tests." The copper and columbium additions to 17-4PH enable precipitation hardening, allowing the material to be strengthened through a controlled aging heat treatment after forming and machining in the solution-annealed (Condition A) state.
Available Product Forms
ASTM A564 17-4PH material is supplied as Bars, Wire, Forgings, Tubing, and Rings per specification requirements. Round bar, hex bar, square bar, and forged billet forms are available in a range of diameters and cross-sections. Both hot-finished and cold-finished conditions are available. Custom forgings, near-net-shape forgings, and machined blanks are available upon request. Contact our materials specialists for non-standard dimensions or custom forging requirements.
Nominal Chemical Composition
| Element |
Symbol |
Nominal % |
Notes |
| Chromium |
Cr |
~16% (15.50–17.50%) |
Primary corrosion resistance element; promotes passive oxide layer |
| Nickel |
Ni |
~4.0% (3.00–5.00%) |
Stabilizes martensite; enhances toughness and ductility |
| Copper |
Cu |
~4.0% (3.00–5.00%) |
Key precipitation hardening element; enables age-hardening strengthening |
| Columbium + Tantalum |
Cb+Ta |
~0.30% (0.15–0.45%) |
Precipitation hardening agent; grain refiner; stabilizes against sensitization |
| Carbon |
C |
0.07% max |
Low carbon for improved corrosion resistance and weldability |
| Manganese |
Mn |
1.00% max |
Deoxidizer; contributes to hardenability |
| Silicon |
Si |
1.00% max |
Deoxidizer; improves oxidation resistance |
| Iron |
Fe |
Balance |
Base metal |
Chemical composition ranges are nominal. Consult the current issue of ASTM A564 for precise minimum/maximum requirements. Aero-Vac provides full mill test reports (MTRs) with certified chemistry for every order.
Key Properties & Specification Details
| Property / Attribute |
Details |
| Specification Number |
ASTM A564 |
| Issuing Organization |
ASTM International |
| Material Type |
Age-Hardening Stainless Steel Bars and Shapes – Hot-Finished or Cold-Finished |
| Alloy Name |
17-4PH (Type 630) – also known as UNS S17400 |
| Nominal Composition |
16Cr 4.0Ni 0.30Cb+Ta 4.0Cu |
| Supply Condition |
Solution-Annealed (Condition A) or Age-Hardened (Conditions H900, H1025, H1075, H1100, H1150, etc.) |
| Available Forms |
Bars, Wire, Forgings, Tubing, Rings; Rounds, Squares, Hexagons, Angles, Tees, Channels |
| Tensile Strength |
High – ranges from ~130 ksi (H1150) to ~190 ksi (H900) depending on aging condition |
| Corrosion Resistance |
Good – superior to standard martensitic stainless steels; comparable to 304 in many environments |
| Machinability |
Good in Condition A (solution-annealed); recommended to machine before aging for best results |
| Weldability |
Good – can be welded in Condition A; post-weld aging restores properties |
| Magnetic Properties |
Magnetic (martensitic microstructure) |
| Certification Available |
AS9100D / ISO 9001, Certificate of Conformance, MTR |
Typical Applications
Aerospace Structural Components: Aircraft frames, bulkheads, gears, shafts, and fittings requiring a combination of high strength, good corrosion resistance, and excellent fatigue performance in service environments where both mechanical and environmental demands are stringent.
Valves, Pumps & Rotating Equipment: High-performance valves, pump shafts, impellers, and rotating equipment components in chemical processing, oil & gas, and power generation where strength and corrosion resistance in aggressive media are required.
High-Strength Fasteners & Tooling: Aerospace-grade bolts, studs, screws, and precision tooling requiring very high strength with good corrosion resistance; 17-4PH is widely used in fasteners that must maintain integrity in corrosive environments.
Defense & Ordnance Applications: Missile and rocket components, gun parts, defense hardware, and structural members for military systems requiring high strength-to-weight ratio, corrosion resistance, and reliable performance under demanding mechanical and environmental conditions.
Medical, Food Processing & Industrial: Surgical instruments, medical device components, food processing equipment, and general industrial parts where corrosion resistance combined with high strength and good surface finish capability are essential requirements.
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