Introduction

17-7PH precipitation hardening stainless steel (also 17-7PH PH stainless steel, 17-7PH high strength stainless steel) is a 17-7PH spring stainless steel that combines austenitic formability with martensitic strength through heat treatment. As a 17-7PH cold rolled stainless steel strip or bar, it delivers high strength and hardness, excellent fatigue resistance, and good spring properties after heat treatment strengthening. Manufactured to ASTM A693 17-7PH stainless steel (UNS S17700) in Condition A, TH1050, or RH950, and available under AMS 5528 (sheet/strip), AMS 5529 (strip for springs), and AMS 5644 (bar/forging), this alloy provides exceptional dimensional stability during and after aging, making it ideal for precision components requiring consistent performance across temperature ranges from cryogenic to 400°C.

Chemical composition(%)                         

Mechanical property

Physical performance

17-7PH Precipitation Hardening Stainless Steel Available Products and Standard

1. ASTM A693 / ASME SA693 

(Standard Specification for Precipitation-Hardening Stainless Steel Plate, Sheet, and Strip)

Grade: Type 631 / 17-7PH (UNS S17700) – 17-7PH precipitation hardening stainless steel, 17-7PH high strength stainless steel

Type: 

• 17-7PH stainless steel Plate

• 17-7PH stainless steel Sheet

• 17-7PH stainless steel Strip (cold rolled or hot rolled)

Size Range:

• Sheet / Strip: 0.025 – 6.0 mm thick × up to 1000 mm wide

• Plate: 6.0 – 100 mm thick

• Length: 1000 – 6000 mm

Surface: Annealed (Condition A), Bright, Ground, Pickled

Testing: Chemical analysis, tensile test (Rm ≥1170 MPa after aging), hardness (≥363 HB), flattening test (for strip), dimensional inspection

2. AMS 5528 (Sheet, Strip, and Plate)

Grade: 17-7PH / UNS S17700 – 17-7PH PH stainless steel in Condition A / TH1050 / RH950

Type: 

• 17-7PH stainless steel Sheet

• 17-7PH stainless steel Strip

• 17-7PH stainless steel Plate

Size Range:

• Thickness: 0.025 – 3.18 mm

• Width: up to 1220 mm

Surface: Annealed (Condition A), Bright, Ground

Testing: Chemical analysis, tensile test (Condition A: Rm ≤105 ksi; aged: up to 220 ksi), hardness, bend test, dimensional inspection

3. AMS 5529 (Cold‑Rolled Strip)

Grade: 17-7PH / UNS S17700 – 17-7PH cold rolled stainless steel strip, 17-7PH spring stainless steel with excellent fatigue resistance and good spring properties

Type: 17-7PH stainless steel Cold‑rolled strip (Condition C, CH900)

Size Range:

• Thickness: 0.025 – 3.18 mm

• Width: up to 305 mm (precision strip)

• Coils

Surface: Cold‑rolled, Bright, Polished

Testing: Chemical analysis, tensile test (Condition C: Rm ≥200 ksi; aged CH900: Rm ≥240 ksi), elongation (≥1%), hardness (≥41 HRC in Condition C, ≥46 HRC after CH900), eddy current test, flattening test, dimensional inspection

4. AMS 5644 / ASTM A564 (Bars and Forgings)

Grade: Type 631 / 17-7PH – 17-7PH heat treatment strengthening with dimensional stability

Type: 

• 17-7PH stainless steel Bar (round, square, hex, flat)

• 17-7PH stainless steel Rod

• 17-7PH stainless steel Forging

Size Range:

• Round bar: 5.5 – 500 mm dia (cold drawn or hot rolled)

• Square/flat bar: 10 – 150 mm thick × up to 500 mm wide

• Wire rod: 3.0 – 13.0 mm dia

Surface: Annealed (Condition A), Bright, Ground, Peeled

Testing: Chemical analysis, tensile test (aged: Rm ≥1172 MPa, Rp0.2 ≥965 MPa), elongation (≥6%), hardness (HBW ≥363 after aging), ultrasonic test (for large bars), dimensional inspection

Application

(1)Springs – 17-7PH stainless steel for springs (flat, coil, or disc springs) leverages its good spring properties and high yield strength after TH1050 or RH950 treatment, maintaining load stability under cyclic stress.

(2) Aerospace – 17-7PH stainless steel for aerospace components (landing gear springs, actuator parts, honeycomb panels) combines excellent fatigue resistance, high strength, and dimensional stability under extreme temperature and vibration.

(3) Washers – 17-7PH stainless steel for washers (lock washers, Belleville washers) benefits from heat treatment strengthening, providing consistent clamping force and corrosion resistance in fastening systems.

(4) Diaphragms – 17-7PH stainless steel for diaphragms (pressure sensors, pumps, valves) offers high strength-to-thickness ratio, excellent fatigue life, and minimal creep, ensuring reliable deflection over millions of cycles.

(5) Precision components – 17-7PH stainless steel for precision components (shafts, couplings, medical instruments, MEMS housings) takes advantage of its dimensional stability and uniform hardness after aging, enabling tight tolerances without post‑machining distortion.

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