Stainless Steel 27-7Mo Annealed
Temper · default condition
UNS S31277 · ASTM A240/A312
Standard supply condition for plate, sheet, pipe and bar; maximum corrosion resistance and ductility.
Values for the Annealed condition
Other 27-7Mo tempers and conditions
27-7Mo is listed in 2 conditions; see the grade overview at 27-7Mo.
- Annealed
- Cold Drawn
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefaultThis page solution annealed (≈1120–1180 °C) and rapid quenched | Standard supply condition for plate, sheet, pipe and bar; maximum corrosion resistance and ductility. | 405 | 800 | 50 | 200 HB | — |
cold drawn / cold worked bar and wire | Use where higher strength and closer tolerance bar are needed (fasteners, shafts) and slight loss of ductility is acceptable. | 730 | 950 | 25 | 30 HRC | 1.7 % IACS |
What is 27-7Mo Annealed?
27-7Mo Annealed is 27-7Mo in the Annealed temper — standard supply condition for plate, sheet, pipe and bar; maximum corrosion resistance and ductility. 27-7Mo Annealed has a yield strength of 405 MPa (58.7 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 60% of stainless steel grades. Elongation at break is 50% and the elastic modulus is 195 GPa (28.3 Msi). 27-7Mo Annealed has a density of 8 g/cm³ (0.289 lb/in³), heavier than 92% of stainless steel grades. It melts at 1,320°C (2,408 °F).
Advantages
- Good corrosion resistance — 88/100, better than 97% of stainless steel grades
- Ductile — tolerates forming and impact — 50%, better than 90% of stainless steel grades
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 86% of stainless steel grades
Limitations
- Difficult to machine — 18/100, worse than 99% of stainless steel grades
- Poor heat conductor — 11.5 W/m·K (6.64 BTU/hr·ft·°F), worse than 97% of stainless steel grades
- High embodied carbon — 6.8 kg CO₂/kg, worse than 95% of stainless steel grades
- Low electrical conductivity — 1.7 % IACS, worse than 93% of stainless steel grades
- Limited service temperature — 400°C (752 °F), worse than 78% of stainless steel grades
27-7Mo Annealed properties
Typical room-temperature values for 27-7Mo Annealed; 11 are specific to this condition. Other listed values are 27-7Mo reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
27-7Mo Annealed has a density of 8 g/cm³ (0.289 lb/in³), heavier than 92% of stainless steel grades. It melts at 1,320°C (2,408 °F).
Mechanical14
27-7Mo Annealed has a yield strength of 405 MPa (58.7 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 60% of stainless steel grades. Elongation at break is 50% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal5
27-7Mo Annealed is rated for continuous service to 400°C (752 °F). It conducts heat at 11.5 W/m·K (6.64 BTU/hr·ft·°F), worse than 97% of stainless steel grades. Thermal expansion is 14.5 µm/m·K (8.06 µin/in·°F).
Electrical3
27-7Mo Annealed conducts electricity at 1.7 % IACS, worse than 93% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is excellent (88/100), better than 97% of stainless steel grades.
Sustainability4
Producing a kilogram of 27-7Mo Annealed takes about 85 MJ of energy and emits 6.8 kg of CO₂ — more than 92% of stainless steel grades. Typical recycled content is 40%.
Manufacturability7
27-7Mo Annealed's machinability is poor (18/100, worse than 99% of stainless steel grades); weldability good (65/100); formability good (60/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 27-7Mo Annealed
Is 27-7Mo easy to machine?
Machine like a nickel alloy: rigid setups, positive-rake carbide, low speed with heavy feed, generous flood coolant, and avoid dwelling to prevent severe work hardening.
Can 27-7Mo be welded?
GTAW/GMAW/SMAW with no preheat, low heat input and interpass below ~150 °C using overmatching Ni-base filler (ERNiCrMo-3/-4 or ERNiCrMo-13); autogenous welds should be avoided in critical corrosion service.
Can 27-7Mo be formed, bent or molded?
Hot work 1150–1200 °C followed by solution anneal and rapid quench; cold forming needs roughly 1.5–2× the force of 316L with springback allowance and interstage annealing on severe draws.
What surface finishes work on 27-7Mo?
Pickle in nitric-hydrofluoric or fully solution anneal after hot work to remove heat tint, then passivate per ASTM A967; electropolishing gives the cleanest surface for high-purity or scrubber duty.
27-7Mo 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 |
|---|---|---|
| Clow carbon for weld corrosion resistance | ≤ 0.02 | 0.01 |
| Si | ≤ 0.5 | 0.3 |
| Mnaids nitrogen solubility | ≤ 3 | 1.5 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.01 | 0 |
| Cr | 26 – 28 | 27 |
| Nistabilizes austenite, SCC resistance | 30 – 32 | 31 |
| Mopitting/crevice resistance | 7 – 8 | 7.5 |
| Cuimproves resistance in reducing acids | 0.5 – 1.5 | 1 |
| Nstrength + pitting resistance | 0.3 – 0.4 | 0.35 |
| Fe | balance | — |
27-7Mo Annealed — frequently asked
What is 27-7Mo Annealed used for?
27-7Mo Annealed is typically used for FGD absorber systems, chemical process piping, pulp bleach plants and seawater desalination equipment. In short: beyond AL-6XN corrosion resistance; highest strength superaustenitic here; hot chloride and acid service.
What is the yield strength of 27-7Mo Annealed?
27-7Mo Annealed has a typical yield strength of 405 MPa (58.7 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 60% of stainless steel grades. Strength varies by condition: see the 2 listed tempers.
Is 27-7Mo Annealed easy to machine?
Not especially — machinability is rated poor (18/100, worse than 99% of stainless steel grades). Machine like a nickel alloy: rigid setups, positive-rake carbide, low speed with heavy feed, generous flood coolant, and avoid dwelling to prevent severe work hardening.
Can 27-7Mo Annealed be welded?
Yes — weldability is rated good (65/100). GTAW/GMAW/SMAW with no preheat, low heat input and interpass below ~150 °C using overmatching Ni-base filler (ERNiCrMo-3/-4 or ERNiCrMo-13); autogenous welds should be avoided in critical corrosion service.
What surface finishes work on 27-7Mo Annealed?
Pickle in nitric-hydrofluoric or fully solution anneal after hot work to remove heat tint, then passivate per ASTM A967; electropolishing gives the cleanest surface for high-purity or scrubber duty.
Can 27-7Mo Annealed be formed, bent or molded?
Hot work 1150–1200 °C followed by solution anneal and rapid quench; cold forming needs roughly 1.5–2× the force of 316L with springback allowance and interstage annealing on severe draws.
What is the maximum service temperature of 27-7Mo Annealed?
27-7Mo Annealed is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip (S31277) — ASTM International (2023)
- ASTM A312/A312M — Seamless, Welded and Heavily Cold Worked Austenitic Stainless Steel Pipes — ASTM International (2022)
- ASTM A479/A276 — Stainless Steel Bars and Shapes — ASTM International (2022)
- ATI 27-7MO Superaustenitic Stainless Steel Technical Data Sheet — ATI (Allegheny Technologies) (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.13B — Corrosion: Materials — ASM International (2005)
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.