Steel A217-WC6
Grade · default condition
ASTM A217
WC6 = 1.25Cr-0.5Mo cast steel, normalized and tempered
The default stocked A217 grade: 1.25Cr-0.5Mo valve and flange castings for steam and hydrocarbon service up to ~540 °C.
Values for the WC6 condition
Other A217 tempers and conditions
A217 is listed in 9 conditions; see the grade overview at A217.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
C-0.5Mo cast steel, normalized and tempered | Cheapest A217 grade for moderate-temperature steam service up to about 450–470 °C where graphitization is not a concern. | 285 | 495 | 28 | 150 HB | 44 W/m·K |
Ni-Cr-Mo cast steel, normalized and tempered | Nickel-bearing grade offering better hardenability and toughness in heavier valve-body sections than WC1. | 330 | 545 | 24 | 180 HB | 42 W/m·K |
Ni-Cr-Mo (1Mo) cast steel, normalized and tempered | Like WC4 but with ~1 % Mo for slightly better elevated-temperature creep strength in thick castings. | 335 | 550 | 24 | 185 HB | 41 W/m·K |
WC6DefaultThis page 1.25Cr-0.5Mo cast steel, normalized and tempered | The default stocked A217 grade: 1.25Cr-0.5Mo valve and flange castings for steam and hydrocarbon service up to ~540 °C. | 345 | 550 | 24 | 170 HB | 40 W/m·K |
2.25Cr-1Mo cast steel, normalized and tempered | Standard grade for hot hydrogen and high-temperature steam service (Nelson-curve applications) up to about 580 °C. | 350 | 560 | 24 | 180 HB | 36 W/m·K |
1.25Cr-0.5Mo (higher C/Si) cast steel, quenched or normalized and… | Higher-strength version of the 1.25Cr-0.5Mo chemistry when 345 MPa minimum yield is required in the casting. | 415 | 620 | 22 | 17 HRC | 42 W/m·K |
5Cr-0.5Mo cast steel, normalized/quenched and tempered | Choose for refinery high-temperature sulfidation and hot-oil service where 5 % Cr scale resistance is needed. | 470 | 690 | 21 | 16 HRC | 34 W/m·K |
9Cr-1Mo cast steel, normalized and tempered | 9 % Cr martensitic casting for the hottest conventional steam and refinery service where oxidation resistance outranks toughness. | 470 | 690 | 21 | 16 HRC | 27 W/m·K |
9Cr-1Mo-V (cast P91/CA6NM-class Grade 91), normalized and tempered | Cast Grade 91: V/Nb/N-microalloyed 9Cr with the highest creep strength in A217, used for supercritical steam valves and headers. | 470 | 660 | 21 | 21 HRC | 27 W/m·K |
What is A217-WC6?
A217-WC6 is A217 in the WC6 grade — the default stocked A217 grade: 1.25Cr-0.5Mo valve and flange castings for steam and hydrocarbon service up to ~540 °C. A217-WC6 has a yield strength of 345 MPa (50 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 75% of steel grades. Elongation at break is 24% and the elastic modulus is 205 GPa (29.7 Msi). A217-WC6 has a density of 7.84 g/cm³ (0.283 lb/in³), lighter than 78% of steel grades. It melts at 1,435°C (2,615 °F).
Advantages
- High service temperature — 540°C (1,004 °F), better than 93% of steel grades
- Tough — resists crack growth — 115 MPa·√m (104.7 ksi·√in), better than 77% of steel grades
Limitations
- Limited formability — 18/100, worse than 84% of steel grades
- Low strength — 345 MPa (50 ksi), worse than 75% of steel grades
A217-WC6 properties
Typical room-temperature values for A217-WC6; 37 are specific to this condition. Other listed values are A217 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A217-WC6 has a density of 7.84 g/cm³ (0.283 lb/in³), lighter than 78% of steel grades. It melts at 1,435°C (2,615 °F).
Mechanical16
A217-WC6 has a yield strength of 345 MPa (50 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 75% of steel grades. Elongation at break is 24% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
A217-WC6 is rated for continuous service to 540°C (1,004 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 64% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
A217-WC6 conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of A217-WC6 takes about 29 MJ of energy and emits 2.1 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 70%.
Manufacturability8
A217-WC6's machinability is good (55/100, better than 62% of steel grades); weldability good (65/100); formability poor (18/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A217-WC6
Is A217 easy to machine?
Machine after normalize-and-temper at 150–215 HB; carbide tooling, rigid setups, and allowance for casting skin/sand inclusions; 9Cr grades (C12/C12A) cut noticeably harder and work-harden edges.
Can A217 be welded?
Weldable with matched low-alloy or 9Cr filler (E8018-B2, E9018-B3, E9015-B9) but requires preheat 150–250 °C (C12A ≥ 200 °C), controlled interpass, and mandatory PWHT — 700–760 °C for WC6/WC9, 730–775 °C for C12A.
Can A217 be formed, bent or molded?
Sand or investment cast only; needs good feeding/risering for heavy valve sections, and full re-austenitize + temper after any major weld repair to restore properties.
What surface finishes work on A217?
Not anodizable; typically shot-blasted then painted, aluminized, or left bare inside insulated high-temperature piping — protect machined faces against atmospheric rusting.
A217 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 |
|---|---|---|
| CGrade WC6 (default); WC1 0.25 max, C12A 0.08–0.12 | 0.05 – 0.2 | 0.13 |
| MnWC6 | 0.5 – 0.8 | 0.65 |
| SiWC6 max | ≤ 0.6 | 0.4 |
| CrWC6; WC9 2.00–2.75, C5 4.00–6.50, C12 8.0–10.0, C12A 8.0–9.5 | 1 – 1.5 | 1.25 |
| MoWC6; WC9/C12 0.90–1.20, C12A 0.85–1.05 | 0.45 – 0.65 | 0.55 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.05 | 0.02 |
| Niresidual for WC6; WC4 0.70–1.10, WC5 0.60–1.00 | ≤ 0.5 | 0.2 |
| Vresidual for WC6; C12A 0.18–0.25 intentional | ≤ 0.03 | 0.01 |
| NbC12A only, 0.06–0.10 (Cb) | ≈ 0.08 | 0.08 |
| NC12A only, 0.030–0.070 | ≈ 0.05 | 0.05 |
| Fe | balance | — |
A217-WC6 — frequently asked
What is A217-WC6 used for?
A217-WC6 is typically used for valve bodies, pressure vessel fittings, steam piping components and petrochemical process equipment. In short: high-temperature Cr-Mo castings; standard for steam valves; covers WC1 through C12A.
What is the yield strength of A217-WC6?
A217-WC6 has a typical yield strength of 345 MPa (50 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 75% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is A217-WC6 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine after normalize-and-temper at 150–215 HB; carbide tooling, rigid setups, and allowance for casting skin/sand inclusions; 9Cr grades (C12/C12A) cut noticeably harder and work-harden edges.
Can A217-WC6 be welded?
Yes — weldability is rated good (65/100). Weldable with matched low-alloy or 9Cr filler (E8018-B2, E9018-B3, E9015-B9) but requires preheat 150–250 °C (C12A ≥ 200 °C), controlled interpass, and mandatory PWHT — 700–760 °C for WC6/WC9, 730–775 °C for C12A.
What surface finishes work on A217-WC6?
Not anodizable; typically shot-blasted then painted, aluminized, or left bare inside insulated high-temperature piping — protect machined faces against atmospheric rusting.
Can A217-WC6 be formed, bent or molded?
Sand or investment cast only; needs good feeding/risering for heavy valve sections, and full re-austenitize + temper after any major weld repair to restore properties.
What is the maximum service temperature of A217-WC6?
A217-WC6 is rated for continuous use to about 540°C (1,004 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A217-WC6 and A217-C5?
WC6 is the default condition — the default stocked A217 grade: 1.25Cr-0.5Mo valve and flange castings for steam and hydrocarbon service up to ~540 °C. C5: choose for refinery high-temperature sulfidation and hot-oil service where 5 % Cr scale resistance is needed. Yield strength is 345 MPa in WC6 versus 470 MPa in C5.
Sources
- ASTM A217/A217M Standard Specification for Steel Castings, Martensitic Stainless and Alloy, for Pressure-Containing Parts, Suitable for High-Temperature Service — ASTM International (2021)
- ASME BPVC Section II Part D — Materials Properties — ASME (2023)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Steel Castings Handbook — Steel Founders' Society of America (1995)
- API RP 941 — Steels for Hydrogen Service at Elevated Temperatures — API (2016)
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.