Stainless Steel 321C11-AC (Spheroidize annealed)
Heat-treated state
EN 321C11 · UNS J92710 · ASTM CF8C · JIS SCS21
Only for non-critical, non-corrosive structural castings; interdendritic carbides remain so intergranular corrosion resistance is not guaranteed.
Values for the AC condition
Other 321C11 tempers and conditions
321C11 is listed in 4 conditions; see the grade overview at 321C11.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SADefault Solution annealed (≈1050–1150 °C, water quenched) per ASTM A351/A743 | Standard supply condition for pressure-containing castings; maximum corrosion resistance and ductility. | 250 | 530 | 39 | 150 HB | — |
Solution annealed then stabilization annealed | Chosen for long-term 500–815 °C service or severe nitric-acid duty, where Nb is fully tied up as NbC before operation. | 255 | 540 | 35 | 155 HB | 2.4 % IACS |
ACThis page Spheroidize annealed | Only for non-critical, non-corrosive structural castings; interdendritic carbides remain so intergranular corrosion resistance is not guaranteed. | 265 | 500 | 25 | 170 HB | 2.3 % IACS |
Centrifugally cast tube/ring, solution annealed | Pipe, ring and sleeve forms with denser, finer structure and slightly higher strength than static castings. | 275 | 550 | 38 | 160 HB | 2.4 % IACS |
What is 321C11-AC?
321C11-AC is 321C11 heat treated to AC — only for non-critical, non-corrosive structural castings; interdendritic carbides remain so intergranular corrosion resistance is not guaranteed. 321C11-AC has a yield strength of 265 MPa (38.4 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 81% of stainless steel grades. Elongation at break is 25% and the elastic modulus is 193 GPa (28 Msi). 321C11-AC 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). SA is the default condition FabDigit quotes; AC is available on request or by drawing note.
Advantages
- Low embodied carbon — 3.6 kg CO₂/kg, better than 83% of stainless steel grades
Limitations
- Limited formability — 15/100, worse than 91% of stainless steel grades
- Hard to polish — 58/100, worse than 85% of stainless steel grades
- Low strength — 265 MPa (38.4 ksi), worse than 81% of stainless steel grades
- Needs corrosion protection — 52/100, worse than 76% of stainless steel grades
321C11-AC properties
Typical room-temperature values for 321C11-AC; 22 are specific to this condition. Other listed values are 321C11 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
321C11-AC 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).
Mechanical16
321C11-AC has a yield strength of 265 MPa (38.4 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 81% of stainless steel grades. Elongation at break is 25% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
321C11-AC is rated for continuous service to 700°C (1,292 °F). It conducts heat at 15.8 W/m·K (9.13 BTU/hr·ft·°F), better than 55% of stainless steel grades. Thermal expansion is 16.6 µm/m·K (9.22 µin/in·°F).
Electrical3
321C11-AC conducts electricity at 2.3 % IACS, better than 55% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (52/100), worse than 76% of stainless steel grades.
Sustainability4
Producing a kilogram of 321C11-AC takes about 53 MJ of energy and emits 3.6 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 75%.
Manufacturability7
321C11-AC's machinability is poor (34/100, worse than 55% of stainless steel grades); weldability very good (72/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 321C11-AC
Is 321C11 easy to machine?
Gummy and work-hardening like 347 — use rigid setups, positive-rake carbide, heavy feed with no dwell, 60–100 m/min, flood coolant.
Can 321C11 be welded?
Very good; weld with ER347/E347 or matching Nb filler, low heat input, no preheat and normally no post-weld solution anneal thanks to Nb stabilization.
Can 321C11 be formed, bent or molded?
Sand, investment and centrifugal casting all viable; Nb reduces fluidity so use higher pour temperature and generous risering to avoid interdendritic shrinkage.
What surface finishes work on 321C11?
Pickle and passivate (HNO₃ or citric) after grinding; not anodizable — electropolish or mechanical polish for hygienic surfaces, casting porosity limits mirror finishes.
321C11 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 |
|---|---|---|
| Ckept low; balance of Nb keyed to actual C | ≤ 0.08 | 0.06 |
| Mn | ≤ 1.5 | 1 |
| Si | ≤ 2 | 1.3 |
| P | ≤ 0.04 | 0.03 |
| S | ≤ 0.04 | 0.02 |
| Cr | 18 – 21 | 19.5 |
| Ni | 9 – 12 | 10.5 |
| Moresidual only | ≤ 0.5 | 0.2 |
| Nb8×C minimum (Nb+Ta); stabilizing addition | ≤ 1 | 0.7 |
| Fe | balance | — |
321C11-AC — frequently asked
What is 321C11-AC used for?
321C11-AC is typically used for exhaust/manifold castings, high-temperature valve bodies and welded pressure castings. In short: highest service temp, 850 °C; stabilized for as-welded use; cast counterpart of 347.
What is the yield strength of 321C11-AC?
321C11-AC has a typical yield strength of 265 MPa (38.4 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 81% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is 321C11-AC easy to machine?
Not especially — machinability is rated poor (34/100, worse than 55% of stainless steel grades). Gummy and work-hardening like 347 — use rigid setups, positive-rake carbide, heavy feed with no dwell, 60–100 m/min, flood coolant.
Can 321C11-AC be welded?
Yes — weldability is rated very good (72/100). Very good; weld with ER347/E347 or matching Nb filler, low heat input, no preheat and normally no post-weld solution anneal thanks to Nb stabilization.
What surface finishes work on 321C11-AC?
Pickle and passivate (HNO₃ or citric) after grinding; not anodizable — electropolish or mechanical polish for hygienic surfaces, casting porosity limits mirror finishes.
Can 321C11-AC be formed, bent or molded?
Sand, investment and centrifugal casting all viable; Nb reduces fluidity so use higher pour temperature and generous risering to avoid interdendritic shrinkage.
What is the maximum service temperature of 321C11-AC?
321C11-AC is rated for continuous use to about 700°C (1,292 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 321C11-SA and 321C11 CENT-SA?
SA is the default condition — standard supply condition for pressure-containing castings; maximum corrosion resistance and ductility. CENT-SA: pipe, ring and sleeve forms with denser, finer structure and slightly higher strength than static castings. Yield strength is 250 MPa in SA versus 275 MPa in CENT-SA.
Sources
- ASTM A351/A351M — Castings, Austenitic, for Pressure-Containing Parts (CF8C) — ASTM International (2022)
- ASTM A743/A743M — Castings, Iron-Chromium-Nickel, Corrosion Resistant — ASTM International (2019)
- ASTM A451/A451M — Centrifugally Cast Austenitic Steel Pipe (CPF8C) — ASTM International (2021)
- BS 3100 — Steel castings for general engineering purposes — BSI (1991)
- EN 10213 / EN 10283 — GX5CrNiNb19-11 (1.4552) — CEN (2016)
- JIS G 5121 — Corrosion-resistant steel castings (SCS21) — JSA (2003)
- ASM Specialty Handbook: Stainless Steels — Cast Stainless (ACI) alloys — ASM International (1994)
- ASM Handbook Vol. 1: Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
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.