Steel A217 C12A
ASTM A217 C12A
A217 C12A is a modified 9Cr-1Mo-V cast steel, the casting counterpart to wrought P91-type material, strengthened by vanadium and nitrogen for the highest creep strength in the A217 family.
Reference datasheet — A217 C12A is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the N+T condition
A217 C12A tempers and conditions
A217 C12A is supplied in 4 conditions, soft to hard. N+T is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick only as an intermediate shop condition; castings must be re-normalized and tempered before service. | 380 | 600 | 24 | 11 HRC | 3 % IACS |
N+T plus post-weld heat treatment 750–770 °C | Condition of weld-repaired or field-welded castings; slightly lower strength and hardness than fresh N+T, with restored HAZ toughness. | 465 | 650 | 22 | 15 HRC | 2.9 % IACS |
N+TDefault Normalized and tempered | Standard and effectively the only delivery condition for C12A castings — mandatory for ASME code service. | 490 | 680 | 22 | 18 HRC | — |
As fabricated | Untempered as-cast martensite — brittle and crack-prone; never supplied or used in service. | 930 | 1,230 | 5 | 41 HRC | 2.7 % IACS |
What is A217 C12A?
A217 C12A is a modified 9Cr-1Mo-V cast steel, the casting counterpart to wrought P91-type material, strengthened by vanadium and nitrogen for the highest creep strength in the A217 family. In the normalized and tempered condition it gives 490 MPa yield, 680 MPa tensile, 22 % elongation and 215 HB (18 HRC) with service to about 600 °C, and is used for steam turbine casings and high-pressure valve bodies. Machining and welding are demanding (machinability 38, weldability 35), with mandatory 750–770 °C PWHT below Ac1. WC9 is the lower-cost choice below 565 °C. A217 C12A has a density of 7.77 g/cm³ (0.281 lb/in³), lighter than 92% of steel grades. It melts at 1,420°C (2,588 °F). A217 C12A has a yield strength of 490 MPa (71.1 ksi) and a tensile strength of 680 MPa (98.6 ksi) — stronger than 61% of steel grades. Elongation at break is 22% and the elastic modulus is 218 GPa (31.6 Msi).
What is A217 C12A used for?
- ultra-supercritical steam turbine casings
- high-pressure valve bodies
- boiler header castings
- advanced fossil power plant components
Advantages
- High service temperature — 600°C (1,112 °F), better than 98% of steel grades
- Good corrosion resistance — 28/100, better than 94% of steel grades
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 81% of steel grades
Limitations
- Low electrical conductivity — 2.9 % IACS, worse than 93% of steel grades
- Poor heat conductor — 26 W/m·K (15 BTU/hr·ft·°F), worse than 87% of steel grades
- Limited formability — 15/100, worse than 87% of steel grades
- Difficult to machine — 38/100, worse than 80% of steel grades
A217 C12A properties
Typical room-temperature values for A217 C12A-N+T; bars are the position among steel grades.
Physical3
A217 C12A has a density of 7.77 g/cm³ (0.281 lb/in³), lighter than 92% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
A217 C12A has a yield strength of 490 MPa (71.1 ksi) and a tensile strength of 680 MPa (98.6 ksi) — stronger than 61% of steel grades. Elongation at break is 22% and the elastic modulus is 218 GPa (31.6 Msi).
Thermal6
A217 C12A is rated for continuous service to 600°C (1,112 °F). It conducts heat at 26 W/m·K (15 BTU/hr·ft·°F), worse than 87% of steel grades. Thermal expansion is 10.8 µm/m·K (6 µin/in·°F).
Electrical3
A217 C12A conducts electricity at 2.9 % IACS, worse than 93% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (28/100), better than 94% of steel grades.
Sustainability4
Producing a kilogram of A217 C12A takes about 32 MJ of energy and emits 2.4 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 75%.
Manufacturability8
A217 C12A's machinability is fair (38/100, worse than 80% of steel grades); weldability fair (35/100); formability poor (15/100).
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 steel family
Yield strength against density for every steel grade FabDigit runs. A217 C12A is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A217 C12A
Is A217 C12A easy to machine?
Machine in the N+T condition at 190–250 HB with rigid setups, coated carbide and moderate speeds; work-hardening and abrasive carbides shorten tool life versus low-alloy cast steel.
Can A217 C12A be welded?
Use matching 9CrMoV-N filler (E9015-B9 / ER90S-B9), 200–250 °C preheat and interpass, no interruption below Ms, and mandatory 750–770 °C PWHT below Ac1; never exceed the tempering temperature.
Can A217 C12A be formed, bent or molded?
Sand-cast with generous risering and controlled Al/N chemistry to protect VN strengthening; hot-tearing-prone sections need progressive solidification and slow shakeout.
A217 C12A 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 | 0.08 – 0.12 | 0.1 |
| Mn | 0.3 – 0.6 | 0.45 |
| Si | 0.2 – 0.5 | 0.35 |
| P | ≤ 0.02 | |
| S | ≤ 0.01 | |
| Cr | 8 – 9.5 | 8.7 |
| Mo | 0.85 – 1.05 | 0.95 |
| V | 0.18 – 0.25 | 0.21 |
| Nblisted as Cb (columbium) in ASTM A217 | 0.06 – 0.1 | 0.08 |
| N | 0.03 – 0.07 | 0.05 |
| Ni | ≤ 0.4 | 0.2 |
| Alkept low to preserve free nitrogen for VN strengthening | ≤ 0.02 | |
| Ti | ≤ 0.01 | |
| Zr | ≤ 0.01 | |
| Fe | balance |
What surface finishes work on A217 C12A?
Not anodizable — protect with high-temperature aluminium/silicone paint, thermal-spray aluminizing or leave insulated; keep surfaces clean of chlorides to avoid corrosion under insulation.
Surface treatments FabDigit runs on 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).
Organic Coating
Black / Phosphate
Thermal Spray
How much does A217 C12A cost?
A217 C12A is a premium-cost 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.
A217 C12A — frequently asked
What is A217 C12A used for?
A217 C12A is typically used for ultra-supercritical steam turbine casings, high-pressure valve bodies, boiler header castings and advanced fossil power plant components. In short: strongest A217 cast grade; cast P91 equivalent; hardest to weld.
What is the yield strength of A217 C12A?
A217 C12A has a typical yield strength of 490 MPa (71.1 ksi) and a tensile strength of 680 MPa (98.6 ksi) — stronger than 61% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is A217 C12A easy to machine?
Not especially — machinability is rated fair (38/100, worse than 80% of steel grades). Machine in the N+T condition at 190–250 HB with rigid setups, coated carbide and moderate speeds; work-hardening and abrasive carbides shorten tool life versus low-alloy cast steel.
Can A217 C12A be welded?
With care — weldability is rated fair (35/100). Use matching 9CrMoV-N filler (E9015-B9 / ER90S-B9), 200–250 °C preheat and interpass, no interruption below Ms, and mandatory 750–770 °C PWHT below Ac1; never exceed the tempering temperature.
What surface finishes work on A217 C12A?
Not anodizable — protect with high-temperature aluminium/silicone paint, thermal-spray aluminizing or leave insulated; keep surfaces clean of chlorides to avoid corrosion under insulation.
Can A217 C12A be formed, bent or molded?
Sand-cast with generous risering and controlled Al/N chemistry to protect VN strengthening; hot-tearing-prone sections need progressive solidification and slow shakeout.
What is the maximum service temperature of A217 C12A?
A217 C12A is rated for continuous use to about 600°C (1,112 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A217 C12A N+T and A217 C12A-F?
N+T is the default condition — standard and effectively the only delivery condition for C12A castings — mandatory for ASME code service. F: untempered as-cast martensite — brittle and crack-prone; never supplied or used in service. Yield strength is 490 MPa in N+T versus 930 MPa in F.
How much does A217 C12A cost?
A217 C12A is a premium-cost 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.
Sources
- ASTM A217/A217M — Steel Castings, Martensitic Stainless and Alloy, for Pressure-Containing Parts, Suitable for High-Temperature Service — ASTM International (2021)
- ASME BPVC Section II Part D — Properties (Metric), P91/C12A allowable stresses and physical properties — ASME (2023)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Steel Castings Handbook, 6th ed. — Steel Founders' Society of America (1995)
- NIMS Creep Data Sheets — modified 9Cr-1Mo steel — National Institute for Materials Science (Japan) (2014)
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.