17-4 PH Stainless Steel properties
17-4 PH is a precipitation-hardening martensitic stainless steel that combines high strength with good corrosion resistance. It is hardened by a simple low-temperature aging treatment. Values below are for the H900 peak-aged condition.
Mechanical properties
| Property | Value |
|---|---|
| Yield strength | 170 ksi (1170 MPa) |
| Ultimate tensile strength | 190 ksi (1310 MPa) |
| Elongation | 10% |
| Hardness | about 40 HRC (Rockwell C) |
| Modulus of elasticity | 28,500 ksi (197 GPa) |
Physical properties
| Property | Value |
|---|---|
| Density | 0.282 lb/in³ (7800 kg/m³) |
| Melting point | about 1400 to 1440 °C |
Thermal properties
| Property | Value |
|---|---|
| Thermal conductivity | 18.3 W/m·K |
| Thermal expansion | 10.8 µm/m·°C |
| Specific heat | 460 J/kg·K |
Values are typical for the grade and condition shown. Actual properties vary with temper, heat treatment, and product form, so use these for comparison and preliminary design and confirm against material certificates for final work.
Compare with other materials
See the Material Properties Comparison, Yield Strength, and Density charts.
Typical uses
17-4 PH is used for pump and valve parts, shafts, fasteners, aerospace fittings, and molds that need high strength with corrosion resistance. It can be machined in the softer solution-treated state and then hardened by a single aging step with minimal distortion.
How it compares
17-4 PH is far stronger than austenitic stainless steels like 304 and 316, approaching alloy-steel strength while keeping useful corrosion resistance. It is less corrosion resistant than 316 but vastly stronger, filling the gap between stainless and high-strength alloy steel.
FAQ
How is 17-4 PH hardened?
By precipitation hardening: a single low-temperature aging treatment, such as H900 at 900 F, strengthens it with little distortion after machining.
What does PH stand for?
Precipitation hardening. Fine particles form during aging and block dislocation movement, raising strength.
Is 17-4 PH as corrosion resistant as 304?
It resists corrosion reasonably well but less than 304 or 316. Its advantage is very high strength rather than maximum corrosion resistance.