Stainless Steel 15-7 Mo
UNS S15700 · AISI/SAE PH15-7Mo · ASTM A693 · also Alloy 632
15-7 Mo (S15700, PH15-7Mo, Alloy 632, ASTM A693) is a semi-austenitic precipitation-hardening stainless with a molybdenum addition, supplied as Condition A sheet and strip for forming and then aged to TH1050, RH950, CH900 or the Condition T, R100 and C tempers.
Values for the Condition A condition
15-7 Mo tempers and conditions
15-7 Mo is supplied in 7 conditions, soft to hard. Condition A is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Condition ADefault solution annealed (~1065 °C, air cooled) | Standard mill-supplied soft condition for blanking, forming and welding before hardening. | 415 | 950 | 25 | 13 HRC | 2.1 % IACS |
austenite conditioned at 760 °C (1400 °F), cooled to ≤16 °C | Intermediate martensitic state produced before the 1050 °F age; supplied only as a processing step, straightening/limited forming still possible. | 760 | 1,030 | 10 | 32 HRC | 2.2 % IACS |
Austenite conditioned at 954 °C (1750 °F) + refrigerated to −73 °C | Transformed-to-martensite state preceding the RH950 age; used when maximum aged strength is required. | 860 | 1,170 | 7 | 36 HRC | 2.2 % IACS |
cold rolled to ~60 % reduction (strip) | Cold-rolled hard strip supplied for spring and diaphragm stock, normally aged afterwards to CH900. | 1,310 | 1,450 | 2 | 43 HRC | 2.1 % IACS |
Austenite conditioned at 760 °C, cooled, then aged 566 °C | The workhorse hardened condition: ~1400 MPa with usable ductility and best toughness of the aged states. | 1,345 | 1,415 | 7 | 45 HRC | — |
Austenite conditioned at 954 °C, refrigerated −73 °C, aged 510 °C | Highest-strength heat-treated condition for springs and highly loaded sheet parts; least ductile and most SCC-sensitive. | 1,520 | 1,620 | 6 | 48 HRC | — |
Condition C strip aged 482 °C | Maximum-strength thin strip/wire condition for springs, bellows and diaphragms; very low ductility. | 1,655 | 1,725 | 2 | 48 HRC | 16 W/m·K |
What is 15-7 Mo?
15-7 Mo (S15700, PH15-7Mo, Alloy 632, ASTM A693) is a semi-austenitic precipitation-hardening stainless with a molybdenum addition, supplied as Condition A sheet and strip for forming and then aged to TH1050, RH950, CH900 or the Condition T, R100 and C tempers. Engineers use it for aerospace sheet parts and springs that must be formed soft and hardened afterwards; Condition A gives 415 MPa yield, 950 MPa tensile and 25% elongation at 92 HRB. Service is limited to 425 °C, corrosion resistance (score 60) is below 304, and the multi-step conditioning cycle adds cost. 17-7 PH is the usual substitute. 15-7 Mo 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). 15-7 Mo has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 62% of stainless steel grades. Elongation at break is 25% and the elastic modulus is 200 GPa (29 Msi).
What is 15-7 Mo used for?
- Aerospace springs
- Washers
- Fittings
Advantages
- Easy to machine — 45/100, better than 84% of stainless steel grades
Limitations
- Difficult to weld — 50/100, worse than 77% of stainless steel grades
15-7 Mo properties
Typical room-temperature values for 15-7 Mo-Condition A; bars are the position among stainless steel grades.
Physical3
15-7 Mo 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).
Mechanical16
15-7 Mo has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 62% of stainless steel grades. Elongation at break is 25% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
15-7 Mo is rated for continuous service to 425°C (797 °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 conducts electricity at 2.1 % IACS, worse than 73% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (60/100), worse than 58% of stainless steel grades.
Sustainability4
Producing a kilogram of 15-7 Mo 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's machinability is fair (45/100, better than 84% of stainless steel grades); weldability fair (50/100); formability good (60/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. 15-7 Mo is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 15-7 Mo
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.
Manufacturability
The process limits FabDigit applies to 15-7 Mo. Every 15-7 Mo part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Fair45 / 100 |
|---|---|
| ISO material group | M.1 |
| Cutting speed (rough / finish) | 150 / 180 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1.5 mm |
| Drill depth limit | 4× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Fair60 / 100 |
|---|---|
| Weldability | Better50 / 100 |
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 |
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).
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
Organic Coating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel 15-7 Mo in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S15700
- AISI / SAE
- PH15-7Mo
- ASTM
- A693
- Trade names
- Alloy 632
How much does 15-7 Mo cost?
15-7 Mo is a premium-cost stainless steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
15-7 Mo — frequently asked
What is 15-7 Mo used for?
15-7 Mo is typically used for aerospace springs, washers and fittings. In short: high-strength PH stainless.
What is the yield strength of 15-7 Mo?
15-7 Mo has a typical yield strength of 415 MPa (60.2 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 62% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 15-7 Mo easy to machine?
Reasonably — machinability is rated fair (45/100, better than 84% 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 be welded?
With care — weldability is rated fair (50/100). 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?
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 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?
15-7 Mo is rated for continuous use to about 425°C (797 °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.
How much does 15-7 Mo cost?
15-7 Mo is a premium-cost stainless steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in 15-7 Mo?
Yes — 15-7 Mo 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
- 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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.