Steel GX10CrMoV9-1-AC (Spheroidize annealed)
Heat-treated state
ASTM A217 Gr. C12A · EN 1.7367
Raw foundry state only — hard, brittle untempered martensite; must be normalized and tempered before machining or service.
Values for the AC condition
Other GX10CrMoV9-1 tempers and conditions
GX10CrMoV9-1 is listed in 5 conditions; see the grade overview at GX10CrMoV9-1.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Interim softening treatment for rough machining or repair of raw castings — never a service condition (no creep allowables). | 360 | 580 | 24 | 10 HRC | 3.3 % IACS |
N+T + post-weld/stress-relief heat treatment 740–770 °C | Condition of castings after weld repair or fabrication welding to pipe; strength drops slightly with each additional temper cycle. | 460 | 630 | 22 | 16 HRC | 3.1 % IACS |
N+TDefault Normalized and tempered | Standard supply condition for all power-plant valve and fitting castings; the only condition with ASME creep allowables. | 490 | 660 | 21 | 19 HRC | — |
Quenched and tempered | Used for very heavy-section castings where still-air normalizing cannot fully harden the core; gives slightly higher strength and better core toughness. | 520 | 700 | 20 | 21 HRC | — |
ACThis page Spheroidize annealed | Raw foundry state only — hard, brittle untempered martensite; must be normalized and tempered before machining or service. | 900 | 1,250 | 6 | 42 HRC | 2.8 % IACS |
What is GX10CrMoV9-1-AC?
GX10CrMoV9-1-AC is GX10CrMoV9-1 heat treated to AC — raw foundry state only — hard, brittle untempered martensite; must be normalized and tempered before machining or service. GX10CrMoV9-1-AC has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,250 MPa (181 ksi) — stronger than 90% of steel grades. Elongation at break is 6% and the elastic modulus is 218 GPa (31.6 Msi). GX10CrMoV9-1-AC 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). N+T is the default condition FabDigit quotes; AC is available on request or by drawing note.
Advantages
- Good corrosion resistance — 30/100, better than 95% of steel grades
- High strength — 900 MPa (131 ksi), better than 90% of steel grades
Limitations
- Limited formability — 3/100, worse than 99% of steel grades
- Difficult to machine — 15/100, worse than 98% of steel grades
- Limited ductility — 6%, worse than 97% of steel grades
- Low fracture toughness — 40 MPa·√m (36.4 ksi·√in), worse than 92% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
GX10CrMoV9-1-AC properties
Typical room-temperature values for GX10CrMoV9-1-AC; 22 are specific to this condition. Other listed values are GX10CrMoV9-1 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
GX10CrMoV9-1-AC 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
GX10CrMoV9-1-AC has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,250 MPa (181 ksi) — stronger than 90% of steel grades. Elongation at break is 6% and the elastic modulus is 218 GPa (31.6 Msi).
Thermal6
GX10CrMoV9-1-AC is rated for continuous service to 250°C (482 °F). It conducts heat at 24 W/m·K (13.9 BTU/hr·ft·°F), worse than 90% of steel grades. Thermal expansion is 10.8 µm/m·K (6 µin/in·°F).
Electrical2
GX10CrMoV9-1-AC has an electrical resistivity of 6.2×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is poor (30/100), better than 95% of steel grades.
Sustainability4
Producing a kilogram of GX10CrMoV9-1-AC takes about 34 MJ of energy and emits 2.6 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 70%.
Manufacturability8
GX10CrMoV9-1-AC's machinability is poor (15/100, worse than 98% of steel grades); weldability poor (15/100); formability not recommended (3/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with GX10CrMoV9-1-AC
Is GX10CrMoV9-1 easy to machine?
Machine in the N+T (or annealed) condition at ~215 HB with rigid setups, coated carbide, moderate speeds and generous coolant; avoid dwelling — the martensitic matrix work-hardens and burnishes.
Can GX10CrMoV9-1 be welded?
Weldable with matching 9CrMoV filler (E9015-B9/ER90S-B9) using 200–250 °C preheat, ≤300 °C interpass, no austenitic filler for creep service, and mandatory 750–770 °C PWHT with cooling below ~100 °C before PWHT; keep Ni+Mn low to avoid depressing Ac1.
Can GX10CrMoV9-1 be formed, bent or molded?
Sand or investment cast with tight N/Al balance and controlled Cr equivalent to avoid δ-ferrite; heavy risers and slow shakeout limit hot tears, and full re-normalizing plus tempering of the whole casting is mandatory after any weld repair.
What surface finishes work on GX10CrMoV9-1?
Not stainless — protect with paint/aluminium-pigmented high-temperature coating, aluminizing or chromizing; oxide scale forms above ~600 °C in steam and must be removed by pickling or blasting before NDT.
GX10CrMoV9-1 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 |
| Si | 0.2 – 0.5 | 0.35 |
| Mn | 0.3 – 0.6 | 0.45 |
| P | ≤ 0.02 | — |
| S | ≤ 0.01 | — |
| Cr | 8 – 9.5 | 8.75 |
| Mo | 0.85 – 1.05 | 0.95 |
| V | 0.18 – 0.25 | 0.21 |
| NbCb | 0.06 – 0.1 | 0.08 |
| Nessential for MX strengthening | 0.03 – 0.07 | 0.05 |
| Nimax; Ni+Mn often limited to ~1.0 to protect Ac1 | ≤ 0.4 | 0.2 |
| Almax — keeps free N available | ≤ 0.02 | — |
| Ti | ≤ 0.01 | — |
| Zr | ≤ 0.01 | — |
| Fe | balance | — |
GX10CrMoV9-1-AC — frequently asked
What is GX10CrMoV9-1-AC used for?
GX10CrMoV9-1-AC is typically used for high-temperature steam valve bodies, power plant pressure castings and high-pressure pipe fittings. In short: cast P91 creep steel; A217 C12A pressure grade; highest creep strength here.
What is the yield strength of GX10CrMoV9-1-AC?
GX10CrMoV9-1-AC has a typical yield strength of 900 MPa (131 ksi) and a tensile strength of 1,250 MPa (181 ksi) — stronger than 90% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is GX10CrMoV9-1-AC easy to machine?
Not especially — machinability is rated poor (15/100, worse than 98% of steel grades). Machine in the N+T (or annealed) condition at ~215 HB with rigid setups, coated carbide, moderate speeds and generous coolant; avoid dwelling — the martensitic matrix work-hardens and burnishes.
Can GX10CrMoV9-1-AC be welded?
Not readily — weldability is rated poor (15/100). Weldable with matching 9CrMoV filler (E9015-B9/ER90S-B9) using 200–250 °C preheat, ≤300 °C interpass, no austenitic filler for creep service, and mandatory 750–770 °C PWHT with cooling below ~100 °C before PWHT; keep Ni+Mn low to avoid depressing Ac1.
What surface finishes work on GX10CrMoV9-1-AC?
Not stainless — protect with paint/aluminium-pigmented high-temperature coating, aluminizing or chromizing; oxide scale forms above ~600 °C in steam and must be removed by pickling or blasting before NDT.
Can GX10CrMoV9-1-AC be formed, bent or molded?
Sand or investment cast with tight N/Al balance and controlled Cr equivalent to avoid δ-ferrite; heavy risers and slow shakeout limit hot tears, and full re-normalizing plus tempering of the whole casting is mandatory after any weld repair.
What is the maximum service temperature of GX10CrMoV9-1-AC?
GX10CrMoV9-1-AC is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between GX10CrMoV9-1 N+T and GX10CrMoV9-1-AC?
N+T is the default condition — standard supply condition for all power-plant valve and fitting castings; the only condition with ASME creep allowables. AC: raw foundry state only — hard, brittle untempered martensite; must be normalized and tempered before machining or service. Yield strength is 490 MPa in N+T versus 900 MPa in AC.
Sources
- ASTM A217/A217M — Steel Castings, Martensitic Stainless and Alloy, for Pressure-Containing Parts (Gr. C12A) — ASTM International (2021)
- EN 10213 — Steel castings for pressure purposes — CEN (2016)
- ASME BPVC Section II Part D — allowable stresses and physical properties, Grade 91 — ASME (2023)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- EPRI/ASM guidance on Grade 91 steel fabrication and heat treatment — EPRI (2015)
- P91/ZG9Cr1MoV 1688 / Mysteel — 1688 / Mysteel (2026)
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.