Stainless Steel 304C15-ST (Solution annealed)
Heat-treated state · default condition
EN 304C15 · ASTM CF8
Standard supply condition for BS 3100 304C15 / ASTM A351 CF8 pressure castings — maximum corrosion resistance and ductility.
Values for the ST condition
Other 304C15 tempers and conditions
304C15 is listed in 3 conditions; see the grade overview at 304C15.
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 | — |
STDefaultThis page 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-ST?
304C15-ST is 304C15 heat treated to ST — standard supply condition for BS 3100 304C15 / ASTM A351 CF8 pressure castings — maximum corrosion resistance and ductility. 304C15-ST 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). 304C15-ST 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).
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-ST properties
Typical room-temperature values for 304C15-ST; 14 are specific to this condition. Other listed values are 304C15 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
304C15-ST 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-ST 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-ST 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-ST 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-ST 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-ST'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. Confirm any required mill or lot documentation when quoting.
Working with 304C15-ST
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.
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.
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 | — |
304C15-ST — frequently asked
What is 304C15-ST used for?
304C15-ST 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-ST?
304C15-ST 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-ST 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-ST 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-ST?
Grit blast, pickle (HNO3/HF) and passivate per ASTM A967; electropolishing gives best hygienic finish but cast porosity limits mirror polish.
Can 304C15-ST 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-ST?
304C15-ST 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.