17-7PH UNS S17700 AISI 631 Age-Hardening Stainless Steel Bars and Plates
This semi-austenitic precipitation-hardening stainless steel contains 17% chromium and 7% nickel, derived from standard 18-8 stainless steel. Soft austenitic matrix in solution-treated condition enables easy forming; its metastable structure transforms after aging to form NiAl precipitates, delivering strength up to 1600MPa with good toughness. It matches 304’s corrosion resistance, outperforms martensitic grades in chloride stress corrosion cracking resistance, serves long-term under 350°C, and features stable conductivity and wear resistance for structural parts and containers.
Applications of 17-7PH
This grade performs steadily below 350℃ and suits structural parts and containers. It serves aerospace, precision instruments, medical implants and chemical anti-corrosion components.
- Aerospace: It is used to manufacture aircraft hulls and structural components, such as wings, fuselage frames and other parts;jet engine parts, such as blades and turbine disks; missile pressure vessels and components, such as missile shells, engine casings, etc.
- Chemical field: It is used to manufacture all kinds of chemical equipment, such as reactors, heat exchangers and storage tanks, etc.; chemical pipelines, valves, springs and fasteners, etc.
- Medical device field: Because of its antibiotic property and corrosion resistance, it can be used to manufacture surgical instruments and implantable medical devices, etc.
- Other fields: It is used to manufacture electronic device housings, connectors and other components; papermaking and metal processing industries, such as press rolls, dryers, tools and dies, etc.
Equivalent Grades and Commonly Used Specifications of 17-7PH
| Steel Grade | Specification | Specification Name |
| 0Cr17Ni7Al /
07Cr17Ni7Al / S51770 |
GB/T 1220 | Stainless steel bars |
| GB/T 1221 | Heat-resistant steel bars | |
| GB/T 4356 | Stainless steel wire rods | |
| GB/T 4237 | Hot rolled stainless steel plate, sheet and strip | |
| GB/T 4238 | Heat-resisting steel plate, sheet and strip | |
| GJB 8268 | Specification for precipitation-hardening stainless steel bars for aviation | |
| UNS S17700 /
631 |
ASTM A564/A564M | Standard Specification for Hot-Rolled and Cold-Finished Age-Hardening Stainless Steel Bars and Shapes |
| ASTM A693 | Standard Specification for Precipitation-Hardening Stainless and Heat-Resisting Steel Plate, Sheet, and Strip | |
| ASTM A313/ ASME SA313 | Standard Specification for Stainless Steel Spring Wire | |
| ASTM A579 / ASME SA579 | Standard Specification for Superstrength Alloy Steel Forgings | |
| ASTM A705 / ASME SA705 | Standard Specification for Age-Hardening Stainless Steel Forgings | |
| AMS 5529 | Steel, Corrosion-Resistant, Sheet and Strip, 17Cr – 7.1Ni – 1.1Al (Alloy 17-7), Solution Heat Treated and Cold Rolled, Precipitation Hardenable | |
| AMS 5568 | Steel, Corrosion- and Heat-Resistant, Welded Tubing 17Cr – 7.1Ni – 1.1Al Solution Heat Treated, Precipitation-Hardenable | |
| AMS 5644 | Steel, Bars and Forgings, Corrosion Resistant 17Cr – 7.1Ni – 1.1Al Precipitation Hardenable Stainless Steel | |
| AMS 5678 | Steel, Corrosion Resistant, Wire, 17Cr – 7.1Ni – 1.1Al, Cold Drawn, Precipitation-Hardenable | |
| AMS 5824 | Steel, Corrosion-Resistant, Welding Wire, 17Cr – 7.1Ni – 1.0Al | |
| 1.4568 / X7CrNiAl17-7 | EN 10088-3 | Stainless Steels Part 3-Technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright products of corrosion resisting steels for general purposes |
| SUS631 | JIS G 4303 | Stainless Steel bars |
| JIS G 4304 | Hot rolled stainless steel sheet and strip | |
| JIS G 4305 | Cold rolled stainless steel sheet and strip | |
| 09Х17Н7Ю | GOST 5632 | High-alloy steels and corrosion-proof, heat-resisting and high-temperature alloys grades |
| Products produced as per other specifications or technical agreements (if need) are available. | ||
Typical Chemical Composition of 17-7PH
|
Elements |
C | Si | Mn | P | S | Ni | Cr | Al |
| Contents% | ≤0.09 | ≤1.00 | ≤1.00 | ≤0.040 | ≤0.030 | 6.50~7.75 | 16.00~18.00 |
0.75~1.50 |
| Products produced as per other specifications or technical agreements (if need) are available. | ||||||||
Typical Heat Treatment Condition and Mechanical Properties of 17-7PH
|
Delivery Condition |
Mechanical Properties and Hardness of Heat-Treated Specimens | ||||||
| Rp0.2/(N/mm2) | Rm/(N/mm2) | A/% | Zb/% | Akv2d/J | HBW |
HRC |
|
|
Solution Treated（1040℃±15℃, water） |
/ | / | / | / | / | ≤229 | ≤98 HRB |
| Precipitation Hardening(RH950, 955℃, 10min-1h,cool rapidly to room temperature; 24h, -75℃,≥8h; Warm in air to room temperature.565℃, 1h,air) | ≥1030 | ≥1280 | ≥6 | ≥10 | / | ≥388 |
≥41 |
|
Precipitation Hardening(TH1050, 760℃, 90min, cool to 15 ± 3°C within 1 h. Hold not less than 30 min, heat to565°C hold for 90 min, air cool.) |
≥965 | ≥1170 | ≥6 | ≥25 | / | ≥352 |
≥38 |
| Products produced as per other specifications or technical agreements (if need) are available. | |||||||
Process Properties
Hot working: The maximum heating temperature is 1150℃, and steel billet or steel ingot charging temperature should not exceed 600℃. The initial heating temperature is 1100℃, and the final processing temperature is ≥950℃. The cooling method is air cooling.
Cold working: Steel has a greater tendency to work hardening. During the cold rolling, cold drawing or stamping, it is advisable to adopt fewer passes and larger deformation, and increase the frequency of solution treatment.
Effect of Martensite Transition Treatment Temperature and Time on Mechanical Properties of 17-7PH at Room Temperature
Effect of Austenitization Temperature and Time on Mechanical Properties of 17-7PH at Room Temperature
Instantaneous Tensile Properties at High Temperature of 17-7PH
|
Test temperature ℃ |
σb, MPa | σ0.2, MPa | ||
| TH 1050 | RH950 | TH 1050 |
RH950 |
|
|
93 |
1301 | 1477 | 1230 | 1406 |
| 204 | 1223 | 1378 | 1160 |
1259 |
|
316 |
1139 | 1294 | 1090 | 1153 |
| 371 | 1090 | 1230 | 1020 |
1083 |
|
426 |
1012 | 1125 | 911 | 963 |
|
482 |
872 | 935 | 633 |
794 |
| 538 | / | 654 | / |
534 |
Endurance and Creep Strength of 17-7PH
|
Test temperature ℃ |
σb/100,MPa | σb/1000,MPa | σ0.1/1000,MPa | σ0.01/10000,MPa | ||||
| TH1050 | RH950 | TH1050 | RH950 | TH1050 | RH950 | TH1050 |
RH950 |
|
|
316 |
1195 | 1322 | 1111 | 1266 | 949 | 886 | 879 | 733 |
| 371 | 914 | 118 | 858 | 1027 | 738 | 612 | 703 |
422 |
|
427 |
773 | 794 | 633 | 647 | 422 | 253 | 316 | 218 |
| 482 | 548 | 429 | 366 | 309 | 162 | 98 | – |
88 |
Corrosion Resistance of 17-7PH
|
S/N |
Corrosion medium | HNO₃10%+HF2% 40~60℃ 3~5mm passivating treatment | Original weight
g |
Weight after 70h of corrosion
g |
Weight loss | |
| g |
% |
|||||
|
1 |
10% H₂SO₄
aqueous solution |
Not passivated | 8.32885 | 6.54882 | 1.78003 | 21 |
| 2 | 8.45552 | 6.92226 | 1.53326 |
18 |
||
|
3 |
Passivated | 8.44493 | 8.44488 | 0.00005 |
0.01 |
|
Product Forms and Size Range of 17-7PH
|
Product forms |
Size range |
|
Bars |
Diameter or side length: 5.0mm~1000mm |
| Flats |
thickness: 4.0mm~1000mm width: 300mm~2200mm |
| Produce as other form and size according to technical requirements are available. | |
