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17-7 PH Stainless Steel (UNS S17700, SUS 631) is a high-strength precipitation-hardening stainless steel widely used in aerospace, petrochemical, and industrial spring applications. Known for its excellent strength-to-weight ratio, good fatigue resistance, and stable mechanical properties after hardening, 17-7 PH is an ideal choice for high-stress and corrosion-resistant components.
As a professional metal materials supplier, we provide 17-7 PH stainless steel sheets, strips, plates, coils, and precision spring materials with complete certifications and global export capability.
Keywords: 17-7 PH Stainless Steel, SUS 631, UNS S17700, 17-7 Stainless Steel Sheet, 17-7 Stainless Steel Strip, 17-7 PH Spring Steel, Precipitation Hardening Stainless Steel
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High Quality
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Advanced Equipment
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Professional Team
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Custom Service
Chemical Composition (Typical, %)
| Element | Content (%) |
|---|---|
| C | ≤ 0.09 |
| Mn | ≤ 1.00 |
| Si | ≤ 1.00 |
| Cr | 16.0 – 18.0 |
| Ni | 6.50 – 7.75 |
| Al | 0.75 – 1.50 |
| P | ≤ 0.040 |
| S | ≤ 0.030 |
Mechanical Properties (Typical)
| Condition | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) | Hardness |
|---|---|---|---|---|
| Annealed (A) | 965 | 690 | 10–12 | HRB 98 Max |
| RH 950 | 1310–1440 | 1170–1310 | 4–6 | HRC 43–47 |
| CH 900 | 1520–1650 | 1440 | 3–5 | HRC 47–51 |
Standard Specifications
| Standard | Description |
|---|---|
| ASTM A693 | Precipitation Hardening Stainless Steel Plate, Sheet & Strip |
| AMS 5528 | 17-7 PH Sheet/Strip |
| AMS 5529 | Cold Rolled Strip |
| AMS 5644 | Bars & Forgings |
Standard Sizes (Metric + Imperial)
Sheets & Plates
| Thickness | Thickness | Width | Length |
|---|---|---|---|
| 0.2–12 mm | 0.008"–0.5" | 1000–1500 mm | 2000–6000 mm |
Precision Strips
| Thickness | Width |
|---|---|
| 0.06–2.0 mm | 5–680 mm |
Bars
| Diameter | Diameter |
|---|---|
| 6–200 mm | 0.25"–8" |
Custom sizes, tight-tolerance spring strips, and slitting available.
Key Features
✔ Excellent high-strength performance after hardening
✔ Outstanding fatigue resistance suitable for dynamic components
✔ Good corrosion resistance compared with standard martensitic steels
✔ Stable mechanical performance in RH950 & CH900 conditions
✔ Ideal for precision springs & aerospace components
✔ Good formability in annealed condition
✔ Consistent performance during long-term usage
Products Applications
17-7 PH stainless steel is widely used in:
Aerospace
Bellows
Aircraft springs
Fasteners
Turbine components
Industrial & Mechanical
High-performance springs
Disc springs & wave springs
Valve diaphragms
Pressure sensor parts
Petrochemical / Energy
Corrosion-resistant components
High-fatigue mechanical parts
Automotive
Exhaust components
High-stress brackets
Sensor housings
f you are sourcing 17-7 PH stainless steel for aerospace components, precision springs, petrochemical parts, or high-strength structural applications, our team is ready to support you with professional material solutions, stable supply, and reliable global delivery.
We provide custom sizes, OEM fabrication, strict QC inspection, and third-party testing (SGS / BV / TUV) to ensure every shipment meets your performance requirements.
Our address
Room 4107, Runfeng Building, Sanqiao New Street, Weiyang District, Xi'an City, Shaanxi Province
Phone Number
+86 15769214734
Product Delivery Standards – 17-7 PH Stainless Steel
Our 17-7 PH stainless steel products are manufactured, inspected, and delivered according to strict international standards to ensure quality, safety, and reliability for global B2B customers.
1. Material Certification
Mill Test Certificate (MTC / EN 10204 3.1 / 3.2) provided for each batch.
Chemical composition and mechanical properties verified per ASTM A693 / AMS 5659 / AMS 5664.
Traceability from raw material to finished product.
2. Inspection & Quality Assurance
100% dimensional inspection before delivery.
Surface quality check: free of scratches, pits, and scale.
Mechanical testing: tensile strength, yield strength, elongation, hardness per heat treatment specification.
Optional third-party inspection (SGS / BV / TUV) available upon request.
3. Heat Treatment Verification
Delivered in specified condition: H900, H1025, H1075, H1150.
Verification of hardness and strength consistent with the required heat treatment.
4. Packaging & Protection
Products securely packaged to prevent corrosion, deformation, and surface damage during transportation.
Wooden crates, pallets, or shrink wrap for sheets, plates, bars, and tubes.
Labels include grade, dimensions, heat number, and quantity.
5. Delivery & Logistics
Global shipping via sea, air, or express courier.
Optional door-to-door service available.
Compliance with international export regulations and customs documentation.
All products are delivered to ensure that customers receive high-strength, corrosion-resistant 17-7 PH stainless steel ready for immediate use in critical applications.
17-7 PH Stainless Steel FAQ (Professional, B2B Focus)
1. What is the main difference between 17-7 PH and 17-4 PH stainless steel?
17-7 PH is designed for spring applications, offering excellent fatigue strength and stable hardening behavior.
17-4 PH provides higher corrosion resistance and higher structural strength.
Summary:
Choose 17-7 PH for springs & flexible components, and 17-4 PH for high-strength structural parts.
2. What product forms are commonly available for 17-7 PH? Can it be made into tubes?
Common supply forms:
Sheet / Plate
Coil / Strip
Precision Spring Strip (A, 1/4H, 1/2H, FH, RH950, CH900)
Wire
Possible but less common:
Thin-wall welded tube
Bellows tube for aerospace applications
Not commonly available:
Large OD thick-wall seamless tubes
3. What are the differences between Condition A, RH 950, and CH 900?
| Condition | Strength | Hardness | Toughness | Typical Use |
|---|---|---|---|---|
| A (Annealed) | Medium | Low | High | Forming, deep drawing |
| RH 950 | High | Medium-High | Moderate | Springs, diaphragms, aerospace parts |
| CH 900 | Very High | High | Low | Maximum-strength spring components |
Form in Condition A → Final age hardening (RH or CH).
4. How is the weldability of 17-7 PH?
Weldable but more difficult than 304/316
Welding may cause uneven precipitation and require post-weld heat treatment
Not recommended for thick or structural welded parts
Best practice: Prefer mechanical forming or cold working whenever possible.
5. Can 17-7 PH be used at elevated temperatures?
Yes, but with limitations:
Excellent performance up to ~370°C (700°F)
Significant strength loss above 400°C (750°F)
Long-term exposure may cause over-aging and property degradation
6. Is 17-7 PH magnetic?
Yes.
Condition A: slightly magnetic
RH950/CH900: strongly magnetic due to martensitic transformation
7. How good is the fatigue strength of 17-7 PH?
Outstanding.
It exceeds the fatigue performance of 301, 304, and 17-4 PH, making it ideal for:
Dynamic springs
Bellows
Diaphragms
High-cycle mechanical components
8. How does its corrosion resistance compare to other stainless steels?
Better than martensitic grades (410/420)
Similar to 301/302
Lower than 304/316 and precipitation grades like 17-4 PH
Not recommended for marine or highly corrosive chloride environments.
9. What are the standard tolerances for 17-7 PH precision strip?
Thickness tolerance: ±0.005–0.02 mm
Width tolerance: ±0.05 mm
Flatness: ≤ 0.5 mm per meter
Surface roughness: Ra 0.2–0.6 μm (depending on finish)
Custom tolerances available.
10. Is 17-7 PH suitable for forming processes such as bending or deep drawing?
Excellent formability in Condition A
Not formable in hard temper (RH/CH)
All forming must be completed prior to precipitation hardening
11. Which international standards apply to 17-7 PH?
ASTM A693 – Plate, Sheet & Strip
AMS 5528 / 5529 – Cold Rolled Strip
AMS 5644 – Bars & Forgings
UNS S17700
12. What are the typical applications of 17-7 PH?
Aerospace springs & diaphragms
Bellows tube and flexible joints
High-precision valve components
Chemical instrumentation parts
High fatigue mechanical elements
High-strength spring strip and clips
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