Stainless Steel 17-7 PH · precip hard
Stainless Steel 17-7 PH-RH950
Properties of the RH950 condition, compared with the other 17-7 PH tempers.
Highest-strength heat-treated temper for bar, wire and thin sheet where ~1450 MPa is needed and some ductility loss is acceptable.
What is 17-7 PH-RH950?
17-7 PH-RH950 is 17-7 PH in the RH950 condition — highest-strength heat-treated temper for bar, wire and thin sheet where ~1450 MPa is needed and some ductility loss is acceptable. 17-7 PH-RH950 has a yield strength of 1,310 MPa (190 ksi) and a tensile strength of 1,450 MPa (210 ksi) — stronger than 99% of stainless steel grades. Elongation at break is 6% and the elastic modulus is 204 GPa (29.6 Msi). 17-7 PH-RH950 has a density of 7.81 g/cm³ (0.282 lb/in³), heavier than 57% of stainless steel grades. It melts at 1,400°C (2,552 °F). Condition A is the default condition FabDigit quotes; RH950 is available on request or by drawing note.
Advantages
- High strength — 1,310 MPa (190 ksi), better than 99% of stainless steel grades
Limitations
- Limited ductility — 6%, worse than 99% of stainless steel grades
- Limited formability — 10/100, worse than 95% of stainless steel grades
- Difficult to weld — 30/100, worse than 89% of stainless steel grades
17-7 PH-RH950 properties
Typical room-temperature values for 17-7 PH-RH950 — 18 properties are specific to this condition; the rest are grade-level values shared by every 17-7 PH temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.
Physical3
17-7 PH-RH950 has a density of 7.81 g/cm³ (0.282 lb/in³), heavier than 57% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical13
17-7 PH-RH950 has a yield strength of 1,310 MPa (190 ksi) and a tensile strength of 1,450 MPa (210 ksi) — stronger than 99% of stainless steel grades. Elongation at break is 6% and the elastic modulus is 204 GPa (29.6 Msi).
Thermal5
It conducts heat at 16.4 W/m·K (9.48 BTU/hr·ft·°F), better than 69% of stainless steel grades. Thermal expansion is 11 µm/m·K (6.11 µin/in·°F).
Electrical3
17-7 PH-RH950 conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 71% of stainless steel grades.
Sustainability4
Producing a kilogram of 17-7 PH-RH950 takes about 60 MJ of energy and emits 5 kg of CO₂ — more than 70% of stainless steel grades. Typical recycled content is 35%.
Manufacturability7
17-7 PH-RH950's machinability is poor (32/100, worse than 62% of stainless steel grades); weldability poor (30/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 17-7 PH tempers and conditions
17-7 PH is also supplied in 6 other conditions. The full side-by-side table is on the 17-7 PH overview.
- Condition ADefaultAs-supplied soft condition for forming, blanking, drawing and welding before hardening; not a service condition where strength is needed.276 MPa yield · 175 HB
- CH900Maximum-strength temper (~1700 MPa) for flat springs, diaphragms and retaining rings in thin gauges; almost no ductility left.1,620 MPa yield · 49 HRC
- RH950Highest-strength heat-treated temper for bar, wire and thin sheet where ~1450 MPa is needed and some ductility loss is acceptable.1,310 MPa yield · 46 HRC
- CCold-rolled strip/wire temper used for springs and flat parts that will be aged to CH900 after forming.1,310 MPa yield · 43 HRC
- TH1050Workhorse hardened temper for parts formed in Condition A: ~1275 MPa with the best ductility and dimensional stability of the hardened tempers.1,170 MPa yield · 42 HRC
Working with 17-7 PH-RH950
Is 17-7 PH easy to machine?
Machine in Condition A with rigid setups, positive rake carbide, heavy feeds and flood coolant (work-hardens badly); rough before ageing and finish after TH1050/RH950 where only light cuts and grinding are practical.
Can 17-7 PH be welded?
GTAW/resistance-weld in Condition A with matching or 17-7 PH filler and no preheat, then give the full conditioning + ageing cycle to restore strength; welding aged material leaves soft, low-ductility zones.
Can 17-7 PH be formed, bent or molded?
Form, draw and blank only in Condition A (behaves like a springy 300-series, allow generous springback); expect ~0.5–1 % growth in TH1050 and shrinkage in RH950, so fixture and allow for dimensional change.
What surface finishes work on 17-7 PH?
Descale after heat treatment (aluminium-rich oxide is tenacious — pickle or grit blast), then passivate per AMS 2700/ASTM A967; takes a good mechanical or electropolish finish and accepts electroless nickel or Cd/Zn-Ni plating with baking to avoid hydrogen embrittlement.
17-7 PH chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C0.09 max per ASTM A693/AMS | ≤ 0.09 | 0.07 |
| Mn | ≤ 1 | 0.5 |
| Si | ≤ 1 | 0.4 |
| P | ≤ 0.04 | — |
| S0.030 max (0.04 in some specs) | ≤ 0.03 | — |
| Cr | 16 – 18 | 17 |
| Ni | 6.5 – 7.75 | 7.1 |
| AlNiAl precipitation hardener | 0.75 – 1.5 | 1.15 |
| Fe | balance | — |
17-7 PH-RH950 — frequently asked
What is 17-7 PH-RH950 used for?
17-7 PH-RH950 is typically used for aerospace springs, belleville washers, retaining rings, diaphragms and bellows, hose and duct clamps and thin-gauge aircraft fittings. In short: high-hardness aerospace PH.
What is the yield strength of 17-7 PH-RH950?
17-7 PH-RH950 has a typical yield strength of 1,310 MPa (190 ksi) and a tensile strength of 1,450 MPa (210 ksi) — stronger than 99% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 17-7 PH-RH950 easy to machine?
Not especially — machinability is rated poor (32/100, worse than 62% of stainless steel grades). Machine in Condition A with rigid setups, positive rake carbide, heavy feeds and flood coolant (work-hardens badly); rough before ageing and finish after TH1050/RH950 where only light cuts and grinding are practical.
Can 17-7 PH-RH950 be welded?
Not readily — weldability is rated poor (30/100). GTAW/resistance-weld in Condition A with matching or 17-7 PH filler and no preheat, then give the full conditioning + ageing cycle to restore strength; welding aged material leaves soft, low-ductility zones.
What surface finishes work on 17-7 PH-RH950?
Descale after heat treatment (aluminium-rich oxide is tenacious — pickle or grit blast), then passivate per AMS 2700/ASTM A967; takes a good mechanical or electropolish finish and accepts electroless nickel or Cd/Zn-Ni plating with baking to avoid hydrogen embrittlement.
Can 17-7 PH-RH950 be formed, bent or molded?
Form, draw and blank only in Condition A (behaves like a springy 300-series, allow generous springback); expect ~0.5–1 % growth in TH1050 and shrinkage in RH950, so fixture and allow for dimensional change.
What is the difference between 17-7 PH Condition A and 17-7 PH-CH900?
Condition A is the default condition — as-supplied soft condition for forming, blanking, drawing and welding before hardening; not a service condition where strength is needed. CH900: maximum-strength temper (~1700 MPa) for flat springs, diaphragms and retaining rings in thin gauges; almost no ductility left. Yield strength is 276 MPa in Condition A versus 1,620 MPa in CH900.
Can FabDigit make parts in 17-7 PH-RH950?
Yes — 17-7 PH-RH950 is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A693 — Precipitation-Hardening Stainless Steel Plate, Sheet and Strip — ASTM International (2016)
- AMS 5644 / AMS 5528 / AMS 5529 / AMS 5678 (17-7 PH bar, sheet, strip, wire) — SAE International (2020)
- EN 10088-2 / EN 10151 (1.4568, X7CrNiAl17-7) — CEN (2014)
- JIS G 4304 / G 4313 (SUS631) — JSA (2019)
- 17-7 PH Stainless Steel product data bulletin — AK Steel / Cleveland-Cliffs (2016)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- MMPDS-2023, Chapter 2 (precipitation-hardening stainless steels) — Battelle/FAA (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.