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| Grade | Code | AISI | Precipitation-Hardening Stainless Steels |
| 17-7PH | 1.4568 | AISI 631 |
17-7PH is a semi-austenitic precipitation-hardening stainless steel grade. It offers good formability in the solution-annealed condition and develops high mechanical strength, hardness and fatigue resistance after suitable transformation and ageing treatments. Its low dimensional change during heat treatment helps maintain close tolerances. The grade also combines good corrosion resistance and elasticity with a high strength-to-weight ratio.
| C % | Mn % | Si % | P % | S % | Cr % | Ni % | Al % | Fe % |
| ≤ 0.09 | ≤ 1.00 | ≤ 1.00 | ≤ 0.04 | ≤ 0.03 | 16.00 – 18.00 | 6.50 – 7.75 | 0.75 – 1.50 | Bal. |
| Product form | Rp0.2 [MPa] | Rm [MPa] | Elongation [%] | Hardness [HB] | Density [g/cm³] |
| Bar | ≥ 965 | ≥ 1172 | ≥ 6 | ≥ 363 | 7.65 |
| Plate | ≥ 1,035 | ≥ 1240 | ≥ 6 | ≥ 353 | 7.65 |
| Sector | Common products |
| Aerospace | Aircraft control-system springs, pressure diaphragms, metal bellows |
| Automotive and transport | Exhaust-system springs, retaining rings, flexible connectors |
| Oil and gas | Downhole equipment springs, Belleville washers, valve springs |
| Chemical processing | Pump diaphragms, expansion bellows, fluid-seal springs |
| Medical | Surgical clips, surgical stapler springs, medical-device return springs |
| Electronics and metrology | Strain gauges, spring electrical contacts, sensor diaphragms |
| Energy and power generation | Turbine sealing rings, high-temperature springs, boiler and heat-exchanger connection elements |
| General machinery and industrial equipment | Disc springs, retaining rings, spring washers |
17-7PH is a precipitation-hardening stainless steel whose mechanical properties can be set at different levels through the selected ageing temperature. The heat-treatment levels known commercially as H1050, H1000 and H900 establish the balance between strength, hardness, toughness and elasticity. H1050 combines high strength with more balanced toughness and dimensional stability. H1000 is an intermediate performance level with increased hardness and fatigue strength. H900 is selected for components requiring maximum strength, elastic recovery and spring performance; however, ductility and subsequent machinability are reduced in this condition. This feature allows 17-7PH to be prepared at different performance levels according to the component's static load, vibration, repeated flexing and operating temperature.
17-7PH, AISI 631, UNS S17700, EN 1.4568, X7CrNiAl17-7
| Product form | ASTM | AMS | Description |
| Bar | ASTM A564/A564M, Type 631 | AMS 5644 | Covers bars and forgings; it may be evaluated in Condition A or in hardened conditions. |
| Plate | ASTM A693/A693M, Type 631 | AMS 5528 | Covers solution-annealed plate products that can subsequently be hardened by ageing. |
| Sheet | ASTM A693/A693M, Type 631 | AMS 5528, AMS 5529 | AMS 5528 covers solution-annealed sheet; AMS 5529 covers solution-annealed and cold-rolled high-strength sheet. |
13-8PH – Suitable for components requiring a combination of high strength, toughness and dimensional stability.
15-5PH – Distinguished by high strength, corrosion resistance and wider availability.
1.4418 – May be considered for bars, shafts and thick-section components requiring both strength and impact toughness.
Outokumpu – Dura 17-7PH / EN 1.4568 / UNS S17700
Carpenter Technology – Custom 631 / 17-7PH / UNS S17700
Note: The information contained in this datasheet is for informational purposes only; no liability is accepted.
