Stainless Steel 304C15
EN 304C15 · ASTM CF8
304C15 is the British Standard (BS 3100) designation for a cast 19Cr-9Ni austenitic stainless steel equivalent to ASTM CF8, supplied solution-treated, as-cast or solution-treated plus HIP.
Reference datasheet — 304C15 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 ST condition
304C15 tempers and conditions
304C15 is supplied in 3 conditions, soft to hard. ST is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Only for non-critical, non-corrosive structural castings where heat treatment cost is avoided; grain-boundary carbides reduce corrosion resistance and toughness. | 245 | 480 | 32 | 155 HB | — |
STDefault Solution annealed | Standard supply condition for BS 3100 304C15 / ASTM A351 CF8 pressure castings — maximum corrosion resistance and ductility. | 250 | 500 | 55 | 140 HB | — |
solution treated and hot isostatically pressed | Investment/precision castings for fatigue- or leak-critical duty; HIP closes microporosity giving higher ductility and fatigue life. | 255 | 520 | 62 | 140 HB | 2.4 % IACS |
What is 304C15?
304C15 is the British Standard (BS 3100) designation for a cast 19Cr-9Ni austenitic stainless steel equivalent to ASTM CF8, supplied solution-treated, as-cast or solution-treated plus HIP. It is the default corrosion-resistant casting alloy for UK and European valve and pump work, combining 250 MPa yield, 500 MPa tensile, 55 % elongation and 140 HB (78 HRB) with good weldability (score 85) and service to 760 °C. Chloride pitting resistance is modest (score 62) and machinability is low (score 40) because the alloy is gummy and work-hardening. Step up to 316C12 (CF8M) for seawater or chloride process service. 304C15 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,400°C (2,552 °F). 304C15 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 91% of stainless steel grades. Elongation at break is 55% and the elastic modulus is 193 GPa (28 Msi).
What is 304C15 used for?
- valve bodies
- pump casings
- marine fittings
- general corrosion-resistant castings
Advantages
- Ductile — tolerates forming and impact — 55%, better than 97% of stainless steel grades
- Readily welded — 85/100, better than 87% of stainless steel grades
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 86% of stainless steel grades
Limitations
- Low strength — 250 MPa (36.3 ksi), worse than 91% of stainless steel grades
- Limited formability — 25/100, worse than 78% of stainless steel grades
304C15 properties
Typical room-temperature values for 304C15-ST; bars are the position among stainless steel grades.
Physical3
304C15 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical15
304C15 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 91% of stainless steel grades. Elongation at break is 55% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
304C15 is rated for continuous service to 760°C (1,400 °F). It conducts heat at 16.2 W/m·K (9.36 BTU/hr·ft·°F), better than 64% of stainless steel grades. Thermal expansion is 17.3 µm/m·K (9.61 µin/in·°F).
Electrical3
304C15 conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 52% of stainless steel grades.
Sustainability4
Producing a kilogram of 304C15 takes about 53 MJ of energy and emits 4.2 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 70%.
Manufacturability8
304C15's machinability is fair (40/100, better than 72% of stainless steel grades); weldability excellent (85/100); formability poor (25/100).
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. 304C15 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 304C15
Is 304C15 easy to machine?
Gummy and work-hardening — use rigid setups, sharp positive-rake carbide, heavy feed with continuous cut, ~60–90 m/min and flood coolant; avoid dwelling.
Can 304C15 be welded?
Excellent with GTAW/SMAW using E308/ER308 (or 308L for as-cast repair); no preheat, keep interpass < 150 °C and re-solution treat large repairs to restore corrosion resistance.
Can 304C15 be formed, bent or molded?
Sand or investment cast with generous risering — solidification shrinkage ~5–6 % and low thermal conductivity demand directional feeding; no cold forming.
304C15 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 |
|---|---|---|
| C0.08 % max, unstabilised | ≤ 0.08 | 0.06 |
| SiBS 3100 limit; ASTM CF8 allows 2.00 max | ≤ 1.5 | 1.1 |
| Mn | ≤ 1.5 | 0.9 |
| P | ≤ 0.04 | 0.03 |
| S | ≤ 0.04 | 0.02 |
| Cr | 18 – 21 | 19.5 |
| Ni | 8 – 11 | 9.5 |
| Moresidual only | ≤ 0.5 | 0.2 |
| Febalance, with 5–20 % delta ferrite in the austenite matrix | balance |
What surface finishes work on 304C15?
Grit blast, pickle (HNO3/HF) and passivate per ASTM A967; electropolishing gives best hygienic finish but cast porosity limits mirror 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 304C15 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- CF8
How much does 304C15 cost?
304C15 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.
304C15 — frequently asked
What is 304C15 used for?
304C15 is typically used for valve bodies, pump casings, marine fittings and general corrosion-resistant castings. In short: baseline cast 304 grade; highest ductility in family; widely stocked BS casting alloy.
What is the yield strength of 304C15?
304C15 has a typical yield strength of 250 MPa (36.3 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 91% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is 304C15 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, sharp positive-rake carbide, heavy feed with continuous cut, ~60–90 m/min and flood coolant; avoid dwelling.
Can 304C15 be welded?
Yes — weldability is rated excellent (85/100). Excellent with GTAW/SMAW using E308/ER308 (or 308L for as-cast repair); no preheat, keep interpass < 150 °C and re-solution treat large repairs to restore corrosion resistance.
What surface finishes work on 304C15?
Grit blast, pickle (HNO3/HF) and passivate per ASTM A967; electropolishing gives best hygienic finish but cast porosity limits mirror polish.
Can 304C15 be formed, bent or molded?
Sand or investment cast with generous risering — solidification shrinkage ~5–6 % and low thermal conductivity demand directional feeding; no cold forming.
What is the maximum service temperature of 304C15?
304C15 is rated for continuous use to about 760°C (1,400 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 304C15-ST and 304C15-AC?
ST is the default condition — standard supply condition for BS 3100 304C15 / ASTM A351 CF8 pressure castings — maximum corrosion resistance and ductility. AC: only for non-critical, non-corrosive structural castings where heat treatment cost is avoided; grain-boundary carbides reduce corrosion resistance and toughness. Yield strength is 250 MPa in ST versus 245 MPa in AC.
How much does 304C15 cost?
304C15 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
- BS 3100 — Steel castings for general engineering purposes (grade 304C15) — BSI (1991)
- ASTM A351/A351M — Castings, Austenitic, for Pressure-Containing Parts (CF8) — ASTM International (2018)
- ASTM A743/A743M — Castings, Iron-Chromium-Nickel, Corrosion Resistant — ASTM International (2019)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (cast stainless steels) — ASM International (1990)
- Steel Castings Handbook, 6th ed. — Steel Founders' Society of America / ASM (1995)
- ASM Handbook Vol.13B — Corrosion: Materials — ASM International (2005)
- GB/T 12230 / GB/T 2100 (ZG06Cr19Ni10) — SAC (2016)
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.