Stainless Steel 17-7 PH-T (Condition T)
Heat-treated state
AISI/SAE 17-7 PH · UNS S17700 · ASTM 631, A693 · EN 1.4568, X7CrNiAl17-7 · JIS SUS631
Intermediate transformed (martensitic) state on the way to TH1050; supplied only when the customer will do the final age.
Values for the T condition
Other 17-7 PH tempers and conditions
17-7 PH is listed in 7 conditions; see the grade overview at 17-7 PH.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Condition ADefault solution annealed (1040 °C, air cooled) | As-supplied soft condition for forming, blanking, drawing and welding before hardening; not a service condition where strength is needed. | 276 | 896 | 35 | 175 HB | — |
TThis page Condition T | Intermediate transformed (martensitic) state on the way to TH1050; supplied only when the customer will do the final age. | 760 | 1,035 | 10 | 32 HRC | 2.2 % IACS |
Condition R-100 | Refrigerated intermediate state preceding the RH950 age; higher final strength route than TH but less dimensional stability. | 830 | 1,140 | 8 | 35 HRC | 2.2 % IACS |
Austenite conditioned (760 °C) + aged 565 °C / 90 min | Workhorse hardened temper for parts formed in Condition A: ~1275 MPa with the best ductility and dimensional stability of the hardened tempers. | 1,170 | 1,275 | 8 | 42 HRC | — |
Austenite conditioned (955 °C) + refrigerated (−73 °C) + aged 510 °C /… | Highest-strength heat-treated temper for bar, wire and thin sheet where ~1450 MPa is needed and some ductility loss is acceptable. | 1,310 | 1,450 | 6 | 46 HRC | — |
Condition C | Cold-rolled strip/wire temper used for springs and flat parts that will be aged to CH900 after forming. | 1,310 | 1,450 | 3 | 43 HRC | 2.2 % IACS |
Cold rolled (Condition C) + aged 480 °C / 1 h | Maximum-strength temper (~1700 MPa) for flat springs, diaphragms and retaining rings in thin gauges; almost no ductility left. | 1,620 | 1,725 | 2 | 49 HRC | — |
What is 17-7 PH-T?
17-7 PH-T is 17-7 PH heat treated to T — intermediate transformed (martensitic) state on the way to TH1050; supplied only when the customer will do the final age. 17-7 PH-T has a yield strength of 760 MPa (110 ksi) and a tensile strength of 1,035 MPa (150 ksi) — stronger than 94% of stainless steel grades. Elongation at break is 10% and the elastic modulus is 200 GPa (29 Msi). 17-7 PH-T 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; T is available on request or by drawing note.
Advantages
- High strength — 760 MPa (110 ksi), better than 94% of stainless steel grades
Limitations
- Limited ductility — 10%, worse than 98% of stainless steel grades
- Difficult to weld — 35/100, worse than 86% of stainless steel grades
17-7 PH-T properties
Typical room-temperature values for 17-7 PH-T; 23 are specific to this condition. Other listed values are 17-7 PH reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
17-7 PH-T 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-T has a yield strength of 760 MPa (110 ksi) and a tensile strength of 1,035 MPa (150 ksi) — stronger than 94% of stainless steel grades. Elongation at break is 10% and the elastic modulus is 200 GPa (29 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-T conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (58/100), worse than 62% of stainless steel grades.
Sustainability4
Producing a kilogram of 17-7 PH-T 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-T's machinability is poor (28/100, worse than 79% of stainless steel grades); weldability fair (35/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 17-7 PH-T
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-T — frequently asked
What is 17-7 PH-T used for?
17-7 PH-T 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-T?
17-7 PH-T has a typical yield strength of 760 MPa (110 ksi) and a tensile strength of 1,035 MPa (150 ksi) — stronger than 94% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 17-7 PH-T easy to machine?
Not especially — machinability is rated poor (28/100, worse than 79% 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-T be welded?
With care — weldability is rated fair (35/100). 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-T?
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-T 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-T?
Yes — 17-7 PH-T is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. 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.