Stainless Steel CG12-AC (Spheroidize annealed)
Heat-treated state
ASTM CG12 · UNS J93001
Only for non-corrosive or purely structural service; carbides at grain boundaries lower ductility and corrosion resistance.
Values for the AC condition
Other CG12 tempers and conditions
CG12 is listed in 2 conditions; see the grade overview at CG12.
- SA
- AC
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SADefault Solution annealed | Standard supply condition required by ASTM A743/A351; maximum corrosion resistance and ductility. | 250 | 520 | 45 | 150 HB | — |
ACThis page Spheroidize annealed | Only for non-corrosive or purely structural service; carbides at grain boundaries lower ductility and corrosion resistance. | 265 | 500 | 25 | 170 HB | 2.2 % IACS |
What is CG12-AC?
CG12-AC is CG12 heat treated to AC — only for non-corrosive or purely structural service; carbides at grain boundaries lower ductility and corrosion resistance. CG12-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). CG12-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
- High service temperature — 870°C (1,598 °F), better than 83% of stainless steel grades
- Low embodied carbon — 3.6 kg CO₂/kg, better than 83% of stainless steel grades
Limitations
- Limited formability — 12/100, worse than 93% of stainless steel grades
- Hard to polish — 55/100, worse than 89% of stainless steel grades
- Low strength — 265 MPa (38.4 ksi), worse than 81% of stainless steel grades
- Needs corrosion protection — 50/100, worse than 78% of stainless steel grades
- Low fracture toughness — 90 MPa·√m (81.9 ksi·√in), worse than 75% of stainless steel grades
CG12-AC properties
Typical room-temperature values for CG12-AC; 23 are specific to this condition. Other listed values are CG12 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
CG12-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
CG12-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
CG12-AC is rated for continuous service to 870°C (1,598 °F). It conducts heat at 14.5 W/m·K (8.38 BTU/hr·ft·°F), worse than 72% of stainless steel grades. Thermal expansion is 16 µm/m·K (8.89 µin/in·°F).
Electrical3
CG12-AC conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (50/100), worse than 78% of stainless steel grades.
Sustainability4
Producing a kilogram of CG12-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%.
Manufacturability8
CG12-AC's machinability is poor (32/100, worse than 62% of stainless steel grades); weldability good (55/100); formability not recommended (12/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CG12-AC
Is CG12 easy to machine?
Machine like 309: rigid setups, sharp positive-rake carbide, heavy constant feed and flood coolant to avoid work-hardened glaze; expect ~45% of AISI 1212 rates.
Can CG12 be welded?
Readily welded with ER309/E309 filler by GTAW/SMAW; keep interpass below ~150 °C and re-solution anneal repaired pressure castings to restore corrosion resistance.
Can CG12 be formed, bent or molded?
Sand or investment cast with generous risering for the wide freezing range and ~2.2% shrinkage; not a cold-forming grade.
What surface finishes work on CG12?
Grit blast, pickle (HNO3-HF) and passivate per ASTM A967 or electropolish; anodizing does not apply.
CG12 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 |
|---|---|---|
| Cmax per ASTM A743 | ≤ 0.12 | 0.08 |
| Mn | ≤ 1.5 | 1 |
| Si | ≤ 2 | 1.2 |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Cr | 20 – 23 | 21.5 |
| Ni | 10 – 13 | 11.5 |
| Moresidual only; not intentionally added | ≤ 0.5 | — |
| Fe | balance | — |
CG12-AC — frequently asked
What is CG12-AC used for?
CG12-AC is typically used for chemical process castings, corrosion-resistant valve components, pump casings for hot chemical service, furnace and heat-treat fixture castings, pipe fittings and elbows and high-temperature flanges and bodies. In short: cast 309-type composition; high-chromium corrosion and heat; wide freezing range casting.
What is the yield strength of CG12-AC?
CG12-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 2 listed tempers.
Is CG12-AC easy to machine?
Not especially — machinability is rated poor (32/100, worse than 62% of stainless steel grades). Machine like 309: rigid setups, sharp positive-rake carbide, heavy constant feed and flood coolant to avoid work-hardened glaze; expect ~45% of AISI 1212 rates.
Can CG12-AC be welded?
Yes — weldability is rated good (55/100). Readily welded with ER309/E309 filler by GTAW/SMAW; keep interpass below ~150 °C and re-solution anneal repaired pressure castings to restore corrosion resistance.
What surface finishes work on CG12-AC?
Grit blast, pickle (HNO3-HF) and passivate per ASTM A967 or electropolish; anodizing does not apply.
Can CG12-AC be formed, bent or molded?
Sand or investment cast with generous risering for the wide freezing range and ~2.2% shrinkage; not a cold-forming grade.
What is the maximum service temperature of CG12-AC?
CG12-AC is rated for continuous use to about 870°C (1,598 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CG12-SA and CG12-AC?
SA is the default condition — standard supply condition required by ASTM A743/A351; maximum corrosion resistance and ductility. AC: only for non-corrosive or purely structural service; carbides at grain boundaries lower ductility and corrosion resistance. Yield strength is 250 MPa in SA versus 265 MPa in AC.
Sources
- ASTM A743/A743M — Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application — ASTM International (2019)
- ASTM A351/A351M — Castings, Austenitic, for Pressure-Containing Parts — ASTM International (2018)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- Steel Castings Handbook, 6th ed. — Steel Founders' Society of America / ASM (1995)
- ASM Handbook Vol. 13B: Corrosion — Materials — ASM International (2005)
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.