17-7 PH Stainless Steel Round Bar (UNS S17700)
17-7 PH Stainless Steel Round Bar is a precipitation-hardening semi-austenitic stainless steel known for its exceptional strength, excellent fatigue resistance, and good corrosion resistance. Identified by UNS S17700, this alloy offers higher strength than 17-4 PH after appropriate heat treatment and is especially valued where spring properties and dimensional stability are critical.
It is widely used in aerospace, mechanical, and precision engineering applications requiring high strength-to-weight ratio and reliable performance.
Key Features
- Very high tensile and yield strength after aging
- Excellent fatigue and stress-corrosion resistance
- Good corrosion resistance comparable to 304 stainless steel
- Outstanding formability in the annealed condition
- Minimal distortion during heat treatment
- Suitable for spring-type and high-load components
Equivalent Grades
| Standard | Grade |
|---|---|
| UNS | S17700 |
| EN | 1.4568 |
| DIN | X7CrNiAl17-7 |
| AMS | 5528 / 5529 |
| JIS | SUS 631 |
Sizes
- Diameter: 3 mm to 300 mm
- Length: 3 m, 6 m, or custom lengths
- Tolerance: H8 / H9 / H11 or as specified
17-7 PH Stainless Steel Chemical Composition
| Element | Percentage (%) |
|---|---|
| Carbon (C) | ≤ 0.09 |
| Chromium (Cr) | 16.0 – 18.0 |
| Nickel (Ni) | 6.5 – 7.75 |
| Aluminum (Al) | 0.75 – 1.50 |
| Manganese (Mn) | ≤ 1.00 |
| Silicon (Si) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 |
UNS S17700 Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | ≥ 1450 MPa |
| Yield Strength | ≥ 1250 MPa |
| Elongation | ≥ 6% |
| Hardness | 44 – 48 HRC |
SS 17-7 PH Physical Properties
| Property | Value |
|---|---|
| Density | 7.80 g/cm³ |
| Melting Point | 1400 – 1440°C |
| Modulus of Elasticity | 200 GPa |
| Thermal Conductivity | 16 W/m·K |
| Electrical Resistivity | 0.73 µΩ·m |
Types of 17-7 PH Stainless Steel Round Bar
- Hot Rolled Round Bar
- Cold Drawn Round Bar
- Bright Bar
- Centerless Ground Bar
- Heat-Treated Round Bar
Applications
- Aerospace springs and fasteners
- Precision mechanical components
- Valve and pump parts
- High-strength shafts and pins
- Diaphragms and bellows
- Industrial spring applications
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