17-4 PH Steel Springs
Stainless Steel 17-4 PH is a precipitation-hardening martensitic Stainless Steel, which has corrosion resistance comparable to austenitic varieties. This makes 17-4 PH well suited for applications that require ease of fabrication with the addition of strength/hardness for improved reliability vs. 302 or 316 alloy where higher tensile strength properties are required.
This valuable combination of properties gives designers the opportunity to add reliability to their products while simplifying fabrication and often reducing costs. This material is typically utilized in Aerospace, Chemical, Petro Chemical, Food Processing Safety Valves, and other industries where corrosion or higher temperatures pose an issue for the application. 17-4 Ph has similar corrosion properties to 304 Stainless Steel.
Typical cross sections are round, rectangular or square. Coiling Technologies can produce 17-4 in a variety of sizes, from .12"5 up to 2.50” diameter. We can process material from 0.008” up to 2.50’ diameter.
17-4 PH Steel Spring Types
17-4 PH Steel Applications
17-4 PH is commonly used in a variety of industries and applications. 17-4 PH’s excellent stress corrosion resistance makes it a popular option for a wide range of applications. If high strength is required H900 condition will yield the highest tensile strength properties. 17-4 PH is most commonly used in:
- Actuators
- Safety relief valves
- Hanger springs in marine applications
You are sure to find what you need here at Coiling Technologies. Contact us today if you need 17-4 PH for your application!
| Technical Specification | 17-4 PH |
|---|---|
| Nominal Composition |
Cr: 15.0 - 17.50 Ni: 3.0 – 5.0 Cu: 3.0 – 5.0 |
| Density |
0.28 lb./in3 |
| Modulus of Elasticity (E) |
28.5 x 106 psi |
| Modulus of Rigidity (G) |
11.00 x 103 ksi |
| Coefficient of Expansion |
6.0 µin/in.-°F (70°F) |
| Electrical Resistivity |
98.0 µΩ.cm |
| Thermal Conductivity |
124 Btu/(hr/ft2/in/°F) |
| Min Size |
0.003 in (0.080 mm) |
| Max Temp |
316oC (600oF) |
| Uses |
Cold drawn & precipitation hardened after fabrication and has high strength. |
17-4 PH Springs FAQs
What is 17-4 PH stainless steel and what does "PH" stand for?
17-4 PH (UNS S17400) is a martensitic precipitation-hardening stainless steel containing approximately 17% chromium and 4% nickel, with copper and niobium additions that enable precipitation hardening. "PH" stands for precipitation hardening—a heat treatment process in which the alloy is aged at a specific temperature, allowing copper-rich precipitate phases to form and significantly increasing strength beyond what the solution-annealed condition achieves. 17-4 PH is one of the most widely used high-strength stainless steels, offering a combination of high tensile strength, moderate corrosion resistance, and good fabrication characteristics.
What H-condition should engineers specify for 17-4 PH springs, and how do the conditions differ?
17-4 PH is available in several age-hardened conditions identified by the aging temperature. Condition H900 (aged at 900°F / 482°C) provides the highest strength and hardness—typically 160,000–190,000 psi tensile—and is most commonly specified for spring applications. Condition H1025 offers slightly lower strength with improved ductility and toughness. Conditions H1075, H1100, and H1150 provide progressively lower strength with progressively better corrosion resistance and ductility. The selection depends on the required spring load, fatigue life expectation, and the corrosivity of the service environment.
How does 17-4 PH compare to 316 stainless steel for high-load spring applications?
17-4 PH in the H900 condition achieves tensile strengths of approximately 170,000–190,000 psi, compared to 316 stainless steel in spring temper at approximately 90,000–130,000 psi depending on wire diameter. This means 17-4 PH can provide equivalent spring force from smaller wire or fewer coils, enabling size and weight reductions. However, 316 stainless offers superior corrosion resistance in chloride environments compared to 17-4 PH in its standard condition. For high-strength requirements with moderate corrosion resistance, 17-4 PH is preferred; for maximum corrosion resistance in aggressive chloride or seawater service, higher alloys such as Inconel 625 should be considered.
What is the maximum service temperature for 17-4 PH springs?
17-4 PH springs in the H900 condition are generally recommended for continuous service up to approximately 600°F (316°C). Above this temperature, the alloy begins to over-age, reducing strength and hardness and accelerating stress relaxation—causing the spring to lose its intended load. For applications above 600°F, higher-temperature alloys such as Inconel 718 or other nickel superalloys are the more appropriate specifications.
What industries commonly specify 17-4 PH stainless springs?
17-4 PH stainless springs are used extensively in: aerospace and defense (hydraulic system springs, actuator components, latching mechanisms), oil and gas (downhole tool springs, wellhead equipment components), food processing and pharmaceutical equipment (high-strength applications with moderate corrosion resistance), chemical processing (valve stems and actuator springs in moderate service environments), medical devices (non-implantable components requiring high strength and corrosion resistance), and precision industrial machinery where high load capacity and moderate corrosion resistance must coexist in a spring material.
Can 17-4 PH springs be used in marine or saltwater environments?
17-4 PH in the H900 condition has moderate corrosion resistance adequate for mild marine atmospheres but potentially insufficient for continuous immersion in seawater or concentrated chloride environments. In these more aggressive conditions, 17-4 PH can be susceptible to chloride pitting and stress corrosion cracking. For demanding marine or seawater applications, materials with higher chloride resistance—Inconel 625, super duplex stainless steel (UNS S32750), or Hastelloy C-276—should be evaluated and specified instead.
What types of springs can be manufactured from 17-4 PH stainless steel?
Coiling Technologies manufactures compression springs, extension springs, torsion springs, and custom wire forms from 17-4 PH stainless wire. Wire diameters typically range from approximately 0.020 inches to 0.500 inches for cold-wound spring production. 17-4 PH is particularly well suited for moderate-to-large diameter springs where high loads are required and where 302 or 17-7 PH stainless wire spring options would require an impractically large wire diameter or coil count to carry the specified load.
