Stainless Steel 15-7 Mo · precip hard
Stainless Steel 15-7 Mo-RH950
Properties of the RH950 condition, compared with the other 15-7 Mo tempers.
Highest-strength heat-treated condition for springs and highly loaded sheet parts; least ductile and most SCC-sensitive.
What is 15-7 Mo-RH950?
15-7 Mo-RH950 is 15-7 Mo in the RH950 condition — highest-strength heat-treated condition for springs and highly loaded sheet parts; least ductile and most SCC-sensitive. 15-7 Mo-RH950 has a yield strength of 1,520 MPa (220 ksi) and a tensile strength of 1,620 MPa (235 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 6% and the elastic modulus is 200 GPa (29 Msi). 15-7 Mo-RH950 has a density of 7.8 g/cm³ (0.282 lb/in³), heavier than 50% 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 — 1,520 MPa (220 ksi), better than 100% of stainless steel grades
Limitations
- Limited ductility — 6%, worse than 99% of stainless steel grades
- Limited formability — 8/100, worse than 97% of stainless steel grades
- Difficult to machine — 22/100, worse than 95% of stainless steel grades
- Limited service temperature — 370°C (698 °F), worse than 84% of stainless steel grades
- Difficult to weld — 45/100, worse than 79% of stainless steel grades
15-7 Mo-RH950 properties
Typical room-temperature values for 15-7 Mo-RH950 — 18 properties are specific to this condition; the rest are grade-level values shared by every 15-7 Mo temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.
Physical3
15-7 Mo-RH950 has a density of 7.8 g/cm³ (0.282 lb/in³), heavier than 50% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical13
15-7 Mo-RH950 has a yield strength of 1,520 MPa (220 ksi) and a tensile strength of 1,620 MPa (235 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 6% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
15-7 Mo-RH950 is rated for continuous service to 370°C (698 °F). It conducts heat at 16 W/m·K (9.24 BTU/hr·ft·°F), better than 58% of stainless steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
15-7 Mo-RH950 conducts electricity at 2.1 % IACS, worse than 73% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 71% of stainless steel grades.
Sustainability4
Producing a kilogram of 15-7 Mo-RH950 takes about 68 MJ of energy and emits 5.4 kg of CO₂ — more than 80% of stainless steel grades. Typical recycled content is 30%.
Manufacturability7
15-7 Mo-RH950's machinability is poor (22/100, worse than 95% of stainless steel grades); weldability fair (45/100); formability not recommended (8/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 15-7 Mo tempers and conditions
15-7 Mo is also supplied in 6 other conditions. The full side-by-side table is on the 15-7 Mo overview.
- Condition ADefaultStandard mill-supplied soft condition for blanking, forming and welding before hardening.415 MPa yield · 92 HRB
- CH900Maximum-strength thin strip/wire condition for springs, bellows and diaphragms; very low ductility.1,655 MPa yield · 48 HRC
- RH950Highest-strength heat-treated condition for springs and highly loaded sheet parts; least ductile and most SCC-sensitive.1,520 MPa yield · 48 HRC
- TH1050The workhorse hardened condition: ~1400 MPa with usable ductility and best toughness of the aged states.1,345 MPa yield · 45 HRC
Working with 15-7 Mo-RH950
Is 15-7 Mo easy to machine?
Machine in Condition A with rigid setups, positive rake carbide and heavy coolant (work-hardens strongly); after TH1050/RH950 expect grinding or low-feed carbide finishing only, so rough to near net size before aging.
Can 15-7 Mo be welded?
GTAW/resistance welding is practical with matching or 17-7 PH filler and no preheat, but the joint must receive the full austenite-conditioning + aging cycle to recover strength; avoid welding in the aged condition.
Can 15-7 Mo be formed, bent or molded?
Form, blank and draw only in Condition A allowing for high springback and dimensional growth (~0.5 %) during aging; hardened tempers are essentially non-formable.
What surface finishes work on 15-7 Mo?
Passivate per AMS 2700/ASTM A967 after machining; grit-blast or pickle scale from heat treatment, and use bright-dip/electropolish or mechanical polish for cosmetic surfaces (no anodizing).
15-7 Mo 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 |
|---|---|---|
| C | ≤ 0.09 | 0.07 |
| Mn | ≤ 1 | 0.5 |
| Si | ≤ 1 | 0.4 |
| P | ≤ 0.04 | — |
| S | ≤ 0.03 | — |
| Cr | 14 – 16 | 15.2 |
| Ni | 6.5 – 7.75 | 7.1 |
| Mo | 2 – 3 | 2.5 |
| Alprecipitation hardener (NiAl) | 0.75 – 1.5 | 1.1 |
| Fe | balance | — |
15-7 Mo-RH950 — frequently asked
What is 15-7 Mo-RH950 used for?
15-7 Mo-RH950 is typically used for aerospace springs, washers and fittings. In short: high-strength PH stainless.
What is the yield strength of 15-7 Mo-RH950?
15-7 Mo-RH950 has a typical yield strength of 1,520 MPa (220 ksi) and a tensile strength of 1,620 MPa (235 ksi) — stronger than 100% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 15-7 Mo-RH950 easy to machine?
Not especially — machinability is rated poor (22/100, worse than 95% of stainless steel grades). Machine in Condition A with rigid setups, positive rake carbide and heavy coolant (work-hardens strongly); after TH1050/RH950 expect grinding or low-feed carbide finishing only, so rough to near net size before aging.
Can 15-7 Mo-RH950 be welded?
With care — weldability is rated fair (45/100). GTAW/resistance welding is practical with matching or 17-7 PH filler and no preheat, but the joint must receive the full austenite-conditioning + aging cycle to recover strength; avoid welding in the aged condition.
What surface finishes work on 15-7 Mo-RH950?
Passivate per AMS 2700/ASTM A967 after machining; grit-blast or pickle scale from heat treatment, and use bright-dip/electropolish or mechanical polish for cosmetic surfaces (no anodizing).
Can 15-7 Mo-RH950 be formed, bent or molded?
Form, blank and draw only in Condition A allowing for high springback and dimensional growth (~0.5 %) during aging; hardened tempers are essentially non-formable.
What is the maximum service temperature of 15-7 Mo-RH950?
15-7 Mo-RH950 is rated for continuous use to about 370°C (698 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 15-7 Mo Condition A and 15-7 Mo-CH900?
Condition A is the default condition — standard mill-supplied soft condition for blanking, forming and welding before hardening. CH900: maximum-strength thin strip/wire condition for springs, bellows and diaphragms; very low ductility. Yield strength is 415 MPa in Condition A versus 1,655 MPa in CH900.
Can FabDigit make parts in 15-7 Mo-RH950?
Yes — 15-7 Mo-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
- AMS 5520 — Steel, Corrosion and Heat Resistant, Sheet, Strip and Plate 15Cr-7Ni-2.5Mo-1.1Al — SAE International (2020)
- AMS 5657 — Steel, Corrosion Resistant, Bars and Wire, 15Cr-7Ni-2.5Mo-1.1Al — SAE International (2018)
- ASTM A693 — Precipitation-Hardening Stainless and Heat-Resisting Steel Plate, Sheet, and Strip — ASTM (2016)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- MMPDS — Metallic Materials Properties Development and Standardization, PH stainless section — Battelle/FAA (2023)
- PH 15-7 Mo semi-austenitic precipitation-hardening stainless datasheet — Cleveland-Cliffs (AK Steel) / Carpenter Technology (2021)
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.