Stainless Steel CF8C
ASTM CF8C · UNS J92710, S34700 · AISI/SAE 347 · EN 1.4550, GX5CrNiNb19-11 · JIS SCS21, SUS347
CF8C (UNS J92710, 1.4550, GX5CrNiNb19-11) is a niobium-stabilized cast austenitic stainless steel, the casting counterpart of wrought 347, in which Nb ties up carbon and prevents sensitization in heavy sections and multi-pass welds.
Reference datasheet — CF8C 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 SA condition
CF8C tempers and conditions
CF8C is supplied in 7 conditions, soft to hard. SA is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot Finished | Economical large-diameter bar and shapes for machined fittings and high-temperature parts; scaled surface, wide tolerances. | 240 | 585 | 45 | 160 HB | — |
Annealed wrought 347 plate/sheet | Use when the same Nb-stabilized chemistry is needed in wrought plate/sheet for weldments mated to CF8C castings. | 245 | 620 | 45 | 160 HB | 2.4 % IACS |
Stabilization annealed | Choose when nitric-acid or long-term 425–815 °C service demands maximum immunity to intergranular and knife-line attack. | 250 | 515 | 36 | 150 HB | 2.4 % IACS |
Hardened | Specify when ASME creep allowables above 540 °C are required (steam headers, reformer and turbine casings). | 250 | 600 | 42 | 165 HB | 2.4 % IACS |
SADefault Solution annealed (≈1065 °C, water quenched), cast per ASTM A351/A743… | Standard supply condition for CF8C valve bodies, pump casings and pressure-containing castings. | 255 | 530 | 39 | 150 HB | — |
Spheroidize annealed | Lowest-cost condition for non-pressure, non-corrosive-service hardware; ductility and IGC resistance are lower than solution annealed. | 260 | 500 | 28 | 160 HB | 2.4 % IACS |
Cold Finished | Pick for tight tolerance, bright surface small-diameter bar with higher yield strength for machined shafts and fasteners. | 415 | 655 | 32 | 190 HB | — |
What is CF8C?
CF8C (UNS J92710, 1.4550, GX5CrNiNb19-11) is a niobium-stabilized cast austenitic stainless steel, the casting counterpart of wrought 347, in which Nb ties up carbon and prevents sensitization in heavy sections and multi-pass welds. It is used for elevated-temperature castings and weldments such as manifolds, turbine casings and valve bodies, with a rated service limit of 816 °C. Solution-annealed properties are near 255 MPa yield, 530 MPa tensile, 39 % elongation and 150 HB (80 HRB), and weldability is rated 85/100. Chloride corrosion resistance (65/100) is below the moly-bearing CF3M/CF8M grades, which are the choice when pitting matters more than heat. CF8C has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,400°C (2,552 °F). CF8C has a yield strength of 255 MPa (37 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 87% of stainless steel grades. Elongation at break is 39% and the elastic modulus is 193 GPa (28 Msi).
What is CF8C used for?
- High-temperature exhaust manifolds
- Turbine casings
- Heavy weldment valve bodies
Advantages
- Readily welded — 85/100, better than 87% of stainless steel grades
- High service temperature — 816°C (1,501 °F), better than 79% of stainless steel grades
Limitations
- Low strength — 255 MPa (37 ksi), worse than 87% of stainless steel grades
- Hard to polish — 60/100, worse than 80% of stainless steel grades
CF8C properties
Typical room-temperature values for CF8C-SA; bars are the position among stainless steel grades.
Physical3
CF8C has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
CF8C has a yield strength of 255 MPa (37 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 87% of stainless steel grades. Elongation at break is 39% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
CF8C is rated for continuous service to 816°C (1,501 °F). It conducts heat at 16.3 W/m·K (9.42 BTU/hr·ft·°F), better than 68% of stainless steel grades. Thermal expansion is 16.6 µm/m·K (9.22 µin/in·°F).
Electrical3
CF8C conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (65/100), better than 56% of stainless steel grades.
Sustainability4
Producing a kilogram of CF8C takes about 55 MJ of energy and emits 5 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 70%.
Manufacturability8
CF8C's machinability is fair (40/100, better than 72% of stainless steel grades); weldability excellent (85/100); formability good (55/100).
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 stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. CF8C is highlighted; hover a dot for its name, or open the interactive family chart.
Working with CF8C
Is CF8C easy to machine?
Gummy and work-hardening — use rigid setups, positive-rake sharp carbide, heavy constant feed, generous coolant and avoid dwelling; expect ~45 % of AISI 1212 rates.
Can CF8C be welded?
Excellent — Nb stabilization means no post-weld solution anneal for IGC resistance; use ER347/E347 filler, low heat input, control delta ferrite 5–15 FN to avoid hot cracking, and stabilize-anneal if knife-line attack is a risk.
Can CF8C be formed, bent or molded?
Castings pour readily with 2.0–2.3 % shrinkage and need generous risering due to low thermal conductivity; wrought 347 cold-forms well but work-hardens fast and requires interstage annealing.
CF8C 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 |
|---|---|---|
| CASTM A351/A743 CF8C | ≤ 0.08 | 0.06 |
| Mn | ≤ 1.5 | 1 |
| Si | ≤ 2 | 1.3 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.02 |
| Cr | 18 – 21 | 19.5 |
| Ni | 9 – 12 | 10.5 |
| Moresidual | ≤ 0.5 | 0.2 |
| NbNb (Cb) ≥ 8×C; Nb+Ta option in some specs | 0.48 – 1 | 0.7 |
| Fe | balance |
What surface finishes work on CF8C?
Passivate per ASTM A967 (nitric or citric) or pickle/electropolish after machining and welding; no anodizing — shot blast plus pickling removes casting scale before final polish.
Surface treatments FabDigit runs on stainless 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).
Passivation
Organic Coating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel CF8C in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- J92710S34700
- AISI / SAE
- 347
- ASTM
- A240 TP347
- EN / DIN / Werkstoff-Nr.
- 1.4550GX5CrNiNb19-111.4552X6CrNiNb18-10
- GB (China)
- 06Cr18Ni11Nb12Kh18N9TL
- JIS
- SCS21SUS347
- Also called
- Cast 347
How much does CF8C cost?
CF8C is a premium-cost stainless 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.
CF8C — frequently asked
What is CF8C used for?
CF8C is typically used for high-temperature exhaust manifolds, turbine casings and heavy weldment valve bodies. In short: highest-temperature CF grade; cast 347 equivalent; stabilized against sensitization.
What is the yield strength of CF8C?
CF8C has a typical yield strength of 255 MPa (37 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 87% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is CF8C easy to machine?
Not especially — machinability is rated fair (40/100, better than 72% of stainless steel grades). Gummy and work-hardening — use rigid setups, positive-rake sharp carbide, heavy constant feed, generous coolant and avoid dwelling; expect ~45 % of AISI 1212 rates.
Can CF8C be welded?
Yes — weldability is rated excellent (85/100). Excellent — Nb stabilization means no post-weld solution anneal for IGC resistance; use ER347/E347 filler, low heat input, control delta ferrite 5–15 FN to avoid hot cracking, and stabilize-anneal if knife-line attack is a risk.
What surface finishes work on CF8C?
Passivate per ASTM A967 (nitric or citric) or pickle/electropolish after machining and welding; no anodizing — shot blast plus pickling removes casting scale before final polish.
Can CF8C be formed, bent or molded?
Castings pour readily with 2.0–2.3 % shrinkage and need generous risering due to low thermal conductivity; wrought 347 cold-forms well but work-hardens fast and requires interstage annealing.
What is the maximum service temperature of CF8C?
CF8C is rated for continuous use to about 816°C (1,501 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CF8C-SA and CF8C-CF?
SA is the default condition — standard supply condition for CF8C valve bodies, pump casings and pressure-containing castings. CF: pick for tight tolerance, bright surface small-diameter bar with higher yield strength for machined shafts and fasteners. Yield strength is 255 MPa in SA versus 415 MPa in CF.
How much does CF8C cost?
CF8C is a premium-cost stainless 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 A351/A351M — Castings, Austenitic, for Pressure-Containing Parts — ASTM (2020)
- ASTM A743/A743M — Castings, Fe-Cr, Fe-Cr-Ni, Corrosion Resistant, General Application — ASTM (2021)
- ASTM A276/A479 & A240 (Type 347/347H) — ASTM (2023)
- EN 10213 / EN 10088 (GX5CrNiNb19-11 1.4552, X6CrNiNb18-10 1.4550) — CEN (2016)
- GB/T 12230 & GB/T 1220 (06Cr18Ni11Nb) — SAC (2016)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- Steel Castings Handbook, 6th ed. — Steel Founders' Society of America / ASM (1995)
- ASM Handbook Vol.1 & Vol.13B — ASM International (2005)
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.