17-4 PH stainless steel, also known as AISI 630, is one of the most widely used precipitation-hardening stainless steels. It is valued for its high strength, corrosion resistance, and hardness, making it suitable for demanding industries such as aerospace, oil and gas, chemical processing, power generation, and marine applications.
A critical aspect of utilizing 17-4 PH stainless steel is its heat treatment process, which allows engineers to adjust the material’s strength, toughness, and corrosion resistance for different applications. This article explains in detail how to heat treat 17-4 PH stainless steel, the different condition states (such as H900, H1025, H1150), step-by-step processes, and key considerations to ensure optimal performance.
17-4 PH stainless steel is a martensitic precipitation-hardening stainless steel containing chromium, nickel, and copper.
Chromium (Cr): ~15–17%
Nickel (Ni): ~3–5%
Copper (Cu): ~3–5%
Niobium (Nb): 0.15–0.45%
Iron (Fe): Balance
High tensile strength (up to 1310 MPa)
Good corrosion resistance similar to 304 stainless steel
Excellent mechanical properties up to 600°F (316°C)
Can be heat treated to different hardness levels
Tailored Mechanical Properties
Heat treatment allows engineers to adjust hardness, yield strength, and toughness.
Improved Wear Resistance
Harder conditions like H900 enhance resistance to abrasion.
Optimized Corrosion Resistance
Certain conditions balance strength and corrosion performance.
Dimensional Stability
Proper heat treatment reduces distortion and stress during service.
Heat the material uniformly to 1900°F (1040°C).
Hold at temperature for 30 minutes minimum.
Rapidly cool to room temperature (air cool or oil quench depending on thickness).
Result: Produces a soft martensitic structure that is workable and ready for aging treatment.
After solution annealing, the material undergoes aging treatment at controlled temperatures. This step causes fine precipitates (mainly copper-rich phases) to form, strengthening the martensitic matrix.
H900 Condition
Heat to 900°F (482°C) for 1 hour.
Air cool.
Highest strength (up to 200 ksi tensile), lower toughness.
H1025 Condition
Heat to 1025°F (552°C) for 4 hours.
Air cool.
Balanced strength and toughness.
H1075 Condition
Heat to 1075°F (580°C) for 4 hours.
Air cool.
Lower strength than H900, improved toughness.
H1150 Condition
Heat to 1150°F (621°C) for 4 hours.
Air cool.
Excellent toughness and corrosion resistance, lower hardness.
H1150 Double Treatment (H1150D)
Heat to 1400°F (760°C) for 2 hours → Air cool.
Reheat to 1150°F (621°C) for 4 hours → Air cool.
Improves resistance to stress corrosion cracking.
| Condition | Tensile Strength (ksi) | Yield Strength (ksi) | Hardness (HRC) | Notes |
|---|---|---|---|---|
| H900 | 190–200 | 170–180 | 44–47 | Highest strength, lower toughness |
| H1025 | ~170 | ~150 | 38–42 | Balanced properties |
| H1075 | ~155 | ~135 | 35–38 | Better toughness |
| H1150 | ~135 | ~105 | 28–32 | Best corrosion resistance |
| H1150D | ~140 | ~110 | 28–32 | Excellent stress corrosion resistance |
Section Thickness
Thicker parts may require longer soaking times.
Cooling Rate
Rapid cooling after solution annealing is critical to avoid retained austenite.
Service Environment
H900 is best for wear and strength, H1150 is best for marine or corrosive environments.
Dimensional Stability
Double aging treatments (H1150D) help reduce distortion.
Aerospace: Turbine blades, engine components
Oil & Gas: Valves, pump shafts, drilling tools
Marine: Propeller shafts, fasteners, offshore platforms
Medical: Surgical tools, orthopedic implants
Chemical Processing: Pressure vessels, heat exchangers
Power Generation: Steam turbines, nuclear reactor components
Flexibility to customize strength and corrosion resistance
Retains high strength at elevated temperatures
Superior resistance to stress corrosion cracking in certain conditions
Wide industrial acceptance with ASME and ASTM approvals
Use precise temperature control furnaces for accuracy.
Ensure uniform heating to avoid uneven properties.
Always air cool unless otherwise specified.
Verify properties with hardness and tensile tests after treatment.
Apply passivation after heat treatment to restore corrosion resistance.
Heat treating 17-4 PH stainless steel is essential to unlock its full potential. The process involves solution annealing followed by precipitation hardening (aging) at different temperatures, producing conditions such as H900, H1025, H1075, and H1150. Each condition offers a unique balance of strength, toughness, and corrosion resistance, making 17-4 PH one of the most versatile stainless steels available.
For industries requiring reliable stainless steel materials and technical guidance, sakysteel provides high-quality 17-4 PH stainless steel products and expert support in selecting the right heat treatment condition for your application. With strict quality control and global service, sakysteel ensures performance, durability, and efficiency in critical projects.
By mastering the heat treatment process, engineers and manufacturers can optimize 17-4 PH stainless steel to meet the demanding requirements of aerospace, marine, energy, and industrial applications.