Nickel Alloy MAR-M247-AC (Spheroidize annealed)
Heat-treated state
UNS N07247 · also 5355
Pick only for non-critical or low-temperature hardware, or as the intermediate state before HIP/heat treatment.
Values for the AC condition
Other MAR-M247 tempers and conditions
MAR-M247 is listed in 7 conditions; see the grade overview at MAR-M247.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Laser powder-bed fusion, as-built | Only for development/repair hardware — fine dendritic structure gives high hardness but very low ductility and residual microcracking. | 720 | 820 | 2 | 45 HRC | 1.3 % IACS |
ACThis page Spheroidize annealed | Pick only for non-critical or low-temperature hardware, or as the intermediate state before HIP/heat treatment. | 790 | 920 | 6 | 41 HRC | 1.4 % IACS |
CC-HTDefault Conventionally (equiaxed) investment cast + full heat treatment | Standard stocked/ordered condition for equiaxed MAR-M247 turbine vanes, blades and integral wheels. | 815 | 965 | 7 | 42 HRC | — |
equiaxed cast, hot isostatically pressed then solution + aged | Choose when casting microporosity must be closed for better ductility and fatigue/creep scatter. | 830 | 1,000 | 9 | 43 HRC | 1.4 % IACS |
laser powder-bed fusion + HIP + solution and age | Post-processed AM condition used to close cracks/porosity and recover cast-like ductility and creep strength. | 850 | 1,000 | 6 | 43 HRC | 1.4 % IACS |
Directionally solidified (columnar grain, properties along <001> growth… | Use for high-pressure turbine blades where transverse grain boundaries and thermal-fatigue cracking must be eliminated. | 895 | 1,035 | 10 | 43 HRC | 1.4 % IACS |
Low-carbon variant (CM247LC / MAR-M247 LC), directionally solidified +… | Low C/Zr/B chemistry developed to avoid DS grain-boundary cracking in thin-wall blades; best DS creep life. | 900 | 1,050 | 12 | 42 HRC | 1.4 % IACS |
What is MAR-M247-AC?
MAR-M247-AC is MAR-M247 heat treated to AC — pick only for non-critical or low-temperature hardware, or as the intermediate state before HIP/heat treatment. MAR-M247-AC has a yield strength of 790 MPa (115 ksi) and a tensile strength of 920 MPa (133 ksi) — stronger than 83% of nickel alloy grades. Elongation at break is 6% and the elastic modulus is 204 GPa (29.6 Msi). MAR-M247-AC has a density of 8.54 g/cm³ (0.309 lb/in³), heavier than 65% of nickel alloy grades. It melts at 1,315°C (2,399 °F). CC-HT is the default condition FabDigit quotes; AC is available on request or by drawing note.
Advantages
- High strength — 790 MPa (115 ksi), better than 83% of nickel alloy grades
Limitations
- Limited formability — 2/100, worse than 99% of nickel alloy grades
- Difficult to weld — 10/100, worse than 94% of nickel alloy grades
- Poor heat conductor — 9.5 W/m·K (5.49 BTU/hr·ft·°F), worse than 93% of nickel alloy grades
- Difficult to machine — 10/100, worse than 93% of nickel alloy grades
- Limited ductility — 6%, worse than 90% of nickel alloy grades
MAR-M247-AC properties
Typical room-temperature values for MAR-M247-AC; 22 are specific to this condition. Other listed values are MAR-M247 reference data and may not represent this condition. Bars are the position among nickel alloy grades.
Physical3
MAR-M247-AC has a density of 8.54 g/cm³ (0.309 lb/in³), heavier than 65% of nickel alloy grades. It melts at 1,315°C (2,399 °F).
Mechanical16
MAR-M247-AC has a yield strength of 790 MPa (115 ksi) and a tensile strength of 920 MPa (133 ksi) — stronger than 83% of nickel alloy grades. Elongation at break is 6% and the elastic modulus is 204 GPa (29.6 Msi).
Thermal6
MAR-M247-AC is rated for continuous service to 980°C (1,796 °F). It conducts heat at 9.5 W/m·K (5.49 BTU/hr·ft·°F), worse than 93% of nickel alloy grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
MAR-M247-AC conducts electricity at 1.4 % IACS, worse than 65% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is good (65/100), worse than 85% of nickel alloy grades.
Sustainability4
Producing a kilogram of MAR-M247-AC takes about 230 MJ of energy and emits 14 kg of CO₂ — more than 91% of nickel alloy grades. Typical recycled content is 30%.
Manufacturability8
MAR-M247-AC's machinability is not recommended (10/100, worse than 93% of nickel alloy grades); weldability not recommended (10/100); formability not recommended (2/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with MAR-M247-AC
Is MAR-M247 easy to machine?
Very difficult: rigid setups, low speeds with ceramic/whisker-reinforced or coated carbide tooling, or (more usually) creep-feed grinding, EDM and ECM for cooling holes and root forms.
Can MAR-M247 be welded?
Essentially non-weldable by conventional fusion (Al+Ti > 6 % → strain-age and liquation cracking); repairs use pre-heated/hot-box laser or micro-TIG with ductile filler, activated-diffusion brazing or LC chemistry.
Can MAR-M247 be formed, bent or molded?
Not wrought — parts are produced by vacuum investment casting in equiaxed or directionally solidified shells; Hf addition eases thin-wall DS filling but requires tight shell/mould reaction control.
What surface finishes work on MAR-M247?
Grit blast plus chemical/vapour aluminide or Pt-Al diffusion coating, MCrAlY overlay and TBC are standard; shot peen and polish blade surfaces; no anodising.
MAR-M247 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 |
|---|---|---|
| Cr | 8 – 8.8 | 8.25 |
| Co | 9 – 11 | 10 |
| W | 9.3 – 10.7 | 10 |
| Mo | 0.5 – 0.8 | 0.65 |
| Ta | 2.8 – 3.3 | 3.05 |
| Alγ′ former | 5.3 – 5.7 | 5.5 |
| Tiγ′ former | 0.9 – 1.2 | 1.05 |
| Hfimproves ductility/castability | 1.2 – 1.6 | 1.4 |
| CLC variant ≈0.07 % | 0.13 – 0.17 | 0.15 |
| BLC variant ≈0.015 % max | 0.01 – 0.02 | 0.02 |
| ZrLC variant ≈0.01 % | 0.03 – 0.08 | 0.05 |
| Feimpurity limit | ≤ 0.5 | — |
| Siimpurity limit | ≤ 0.15 | — |
| Mnimpurity limit | ≤ 0.15 | — |
| Simpurity limit | ≤ 0.02 | — |
| Nibalance ≈59 % | balance | — |
MAR-M247-AC — frequently asked
What is MAR-M247-AC used for?
MAR-M247-AC is typically used for turbine blades, turbine vanes and industrial gas turbine hot components. In short: hottest-running cast blade alloy; DS and equiaxed castings; grinding and EDM only.
What is the yield strength of MAR-M247-AC?
MAR-M247-AC has a typical yield strength of 790 MPa (115 ksi) and a tensile strength of 920 MPa (133 ksi) — stronger than 83% of nickel alloy grades. Strength varies by condition: see the 7 listed tempers.
Is MAR-M247-AC easy to machine?
Not especially — machinability is rated not recommended (10/100, worse than 93% of nickel alloy grades). Very difficult: rigid setups, low speeds with ceramic/whisker-reinforced or coated carbide tooling, or (more usually) creep-feed grinding, EDM and ECM for cooling holes and root forms.
Can MAR-M247-AC be welded?
Not readily — weldability is rated not recommended (10/100). Essentially non-weldable by conventional fusion (Al+Ti > 6 % → strain-age and liquation cracking); repairs use pre-heated/hot-box laser or micro-TIG with ductile filler, activated-diffusion brazing or LC chemistry.
What surface finishes work on MAR-M247-AC?
Grit blast plus chemical/vapour aluminide or Pt-Al diffusion coating, MCrAlY overlay and TBC are standard; shot peen and polish blade surfaces; no anodising.
Can MAR-M247-AC be formed, bent or molded?
Not wrought — parts are produced by vacuum investment casting in equiaxed or directionally solidified shells; Hf addition eases thin-wall DS filling but requires tight shell/mould reaction control.
What is the maximum service temperature of MAR-M247-AC?
MAR-M247-AC is rated for continuous use to about 980°C (1,796 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between MAR-M247 CC-HT and MAR-M247 AM-AB?
CC-HT is the default condition — standard stocked/ordered condition for equiaxed MAR-M247 turbine vanes, blades and integral wheels. AM-AB: only for development/repair hardware — fine dendritic structure gives high hardness but very low ductility and residual microcracking. Yield strength is 815 MPa in CC-HT versus 720 MPa in AM-AB.
Sources
- AMS 5355 — Nickel Alloy Castings, Investment (corrosion & heat resistant) — SAE International (2018)
- ASM Handbook Vol. 1: Properties and Selection — Superalloys — ASM International (1990)
- Superalloys II / Superalloys: A Technical Guide — Wiley / ASM International (2002)
- Cannon-Muskegon CM247LC alloy data sheet — Cannon-Muskegon (Consolidated Precision Products) (2020)
- Cast nickel superalloy mechanical and thermophysical property compilations — NASA / MMPDS-type sources (2019)
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.