Chemical composition
Nominal: mid-range where both limits are given, the cap where only a maximum is, balance takes the remainder. Exact specified ranges below.
| Element | Name | Content % | |
|---|---|---|---|
| Main elements4 elements | |||
| Fe | Iron | Bal. | |
| Cr | Chromium | 16 – 18% | |
| Ni | Nickel | 6.5 – 7.7% | |
| Al | Aluminium | 0.75 – 1.5% | |
| Element | Name | Content % | |
|---|---|---|---|
| Minor & residual5 elements | |||
| C | Carbon | ≤ 0.09% | |
| Mn | Manganese | ≤ 1% | |
| Si | Silicon | ≤ 1% | |
| P | Phosphorus | ≤ 0.04% | |
| S | Sulphur | ≤ 0.03% | |
Mechanical minima by form
Guaranteed values differ by form, size and delivery condition; quotations confirm the specification, form, size and condition.
| Form | Condition | Rm MPa | Rp0.2 MPa | A ≥ % | Other requirements and notes |
|---|---|---|---|---|---|
| Bar and forgings | |||||
| Bar and shapes (≤100 mm, longitudinal) | RH950: 955 °C for 10 min to 1 h, cooled rapidly to room temperature; within 24 h cooled to −75 °C ±10 and held at least 8 h; warmed in air to room temperature; then 510 °C for 1 h, air cooled | ≥ 1280 (186 ksi) | ≥ 1030 (149 ksi) | ≥ 6 | Also specified: Reduction of area Z ≥ 10 % · Hardness ≥ 388 HBW / 41 HRC RH950 includes a mandatory sub-zero step at −75 °C. Condition A (solution-treated) delivery hardness ≤98 HRB. |
| Bar and shapes (≤150 mm, longitudinal) | TH1050: 760 °C for 90 min, cooled to 15 °C ±3 within 1 h and held at least 30 min, then 565 °C for 90 min, air cooled | ≥ 1170 (170 ksi) | ≥ 965 (140 ksi) | ≥ 6 | Also specified: Reduction of area Z ≥ 25 % · Hardness ≥ 352 HBW / 38 HRC No sub-zero step needed. Condition A (solution-treated) delivery hardness ≤98 HRB. |
| Bars (EN 10088-3, ≤30 mm) | +AT (solution annealed, as delivered) | ≤ 850 | — | — | Also specified: Hardness ≤ 255 HBW |
| Plate, sheet and strip | |||||
| Plate, sheet and strip (>0.010–4.0 in) | Condition A: solution treated at 1065 ± 15 °C, not precipitation hardened | ≥ 1035 (150 ksi) | ≥ 380 (55 ksi) | ≥ 20 | |
| Plate, sheet and strip (0.020–0.1874 in) | TH1050: conditioned at 760 °C for 90 min, cooled to 15 ± 3 °C within 1 h and held ≥30 min, aged at 566 °C for 90 min | ≥ 1240 (180 ksi) | ≥ 1035 (150 ksi) | ≥ 6 | |
| Plate, sheet and strip (0.1875–0.625 in) | TH1050 | ≥ 1170 (170 ksi) | ≥ 965 (140 ksi) | ≥ 7 | |
| Plate, sheet and strip (0.020–0.1874 in) | RH950: conditioned at 954 °C for 10 min and rapidly cooled, cooled to −73 °C within 24 h and held ≥8 h, aged at 510 °C for 1 h | ≥ 1450 (210 ksi) | ≥ 1310 (190 ksi) | ≥ 4 | |
| Plate, sheet and strip (0.1875–0.625 in) | RH950 | ≥ 1380 (200 ksi) | ≥ 1240 (180 ksi) | ≥ 6 | |
| Cold-rolled strip (0.0015–0.050 in) | Mill cold-rolled, Condition C, not aged | ≥ 1380 (200 ksi) | ≥ 1205 (175 ksi) | ≥ 1 | |
| Cold-rolled strip (0.0015–0.050 in) | CH900: mill cold-rolled, then aged at 482 °C | ≥ 1655 (240 ksi) | ≥ 1580 (229 ksi) | ≥ 1 | |
| Cold-rolled strip (EN 10088-2, ≤8 mm) | +AT (solution annealed, as delivered) | ≤ 1030 | — | ≥ 19 | |
| Cold-rolled strip (EN 10088-2, ≤8 mm) | +P1450 (precipitation hardened) | ≥ 1450 | ≥ 1310 | ≥ 2 | |
| Wire and filler metals | |||||
| Spring wire | Supplied cold drawn to Condition C; after coiling, 482 °C for 1 h, air cooled, to reach CH900 | — | — | — | |
Where this grade is recommended
Matched in 1 service conditions; ranks and scores computed from the condition-scoring matrix.
| Service condition | Industry | Temperature | Rank | Score |
|---|---|---|---|---|
| Lightweight parts & springs | Automotive & Racing | 150 – 300 °C | 1 / 7 | 84 |
Designations & equivalents
| W.Nr. (Germany) | 1.4568 |
| EN designation | X7CrNiAl17-7 |
| Trade name(s) | 17-7PH / Type 631 |
| ASTM / AISI | A313 / A564 / A693 / A705 (Type 631) |
| AMS (SAE aerospace) | 5528 / 5529 / 5568 / 5644 |
| JIS (Japan) | SUS631 |
| GOST (Russia) | ≈ 09Х17Н7Ю |
Cross-references are common near-equivalents for search and shortlisting; substitution across standards requires clause-by-clause verification. All grades in one cross-reference table →
Applicable standards
10 specifications. Name the standard and its edition on the order.
Guaranteed values and required tests differ between specifications — see Mechanical minima by form for the figures per form.
Frequently asked questions
What is 17-7PH Stainless · UNS S17700?
17-7PH Stainless · UNS S17700 — PH stainless steel. Semi-austenitic PH — form first, age after: springs, diaphragms, washers
What is the maximum service temperature of S17700?
Typically about 315 °C; the practical limit depends on media, stress and design life — acceptance per the governing standard.
What is the tensile strength of S17700?
The specified minimum tensile strength is 1450 MPa for the main product form. Minima for other forms and sizes are listed under "Mechanical minima by form" on this page.
Which standards cover S17700?
ASTM A693, ASTM A313/A313M, ASTM A564/A564M, ASTM A705/A705M, AMS 5528, AMS 5529, AMS 5568, AMS 5644, EN 10088-2 (sheet, plate, strip), EN 10088-3 (bar, rod, wire, sections)
Where is S17700 typically used?
Lightweight parts & springs (Automotive & Racing)
In which forms is S17700 available?
Tube, plate, strip, bar, forgings, wire and other forms — sizes and delivery condition confirmed per order, with EN 10204 3.1 / 3.2 certification.
Same series
Download PDF datasheet
This grade’s datasheet as an A4 PDF — for filing, printing or forwarding to colleagues.
Download PDF datasheetSupply & enquiry
Tube & pipeφ1 – 219 × 0.25 – 25 mm
Plate4.76 – 80 mm
Barφ8 – 300 mm
Wire & filler metalsφ0.01 – 8 mmFor this grade we can supply, against your service conditions:
- Tube, plate, strip, bar, forgings, wire and more — with size range and lead time
- Chemistry and mechanical test report (EN 10204 3.1 / 3.2)
- Like-for-like alternatives and selection advice
- Applicable standards and inspection scope
Or email us: info@kochlin.com