Stainless Steel CG8M-AC (Spheroidize annealed)
Heat-treated state
ASTM CG8M · UNS J93000
Only for non-corrosive structural use or as an intermediate state; interdendritic carbides reduce corrosion resistance and toughness.
Values for the AC condition
Other CG8M tempers and conditions
CG8M is listed in 3 conditions; see the grade overview at CG8M.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ACThis page Spheroidize annealed | Only for non-corrosive structural use or as an intermediate state; interdendritic carbides reduce corrosion resistance and toughness. | 285 | 530 | 28 | 180 HB | 2 % IACS |
STDefault Solution annealed | Standard supply condition for all CG8M castings — maximum corrosion resistance and ductility. | 290 | 550 | 40 | 170 HB | 2 % IACS |
hot isostatically pressed then solution treated | Choose for thick-section or fatigue-critical castings where internal microporosity must be closed. | 300 | 570 | 48 | 175 HB | 2 % IACS |
What is CG8M-AC?
CG8M-AC is CG8M heat treated to AC — only for non-corrosive structural use or as an intermediate state; interdendritic carbides reduce corrosion resistance and toughness. CG8M-AC has a yield strength of 285 MPa (41.3 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 74% of stainless steel grades. Elongation at break is 28% and the elastic modulus is 193 GPa (28 Msi). CG8M-AC has a density of 7.98 g/cm³ (0.288 lb/in³), heavier than 85% of stainless steel grades. It melts at 1,370°C (2,498 °F). ST is the default condition FabDigit quotes; AC is available on request or by drawing note.
Limitations
- Limited formability — 18/100, worse than 89% of stainless steel grades
- Hard to polish — 60/100, worse than 80% of stainless steel grades
- Low electrical conductivity — 2 % IACS, worse than 77% of stainless steel grades
- Difficult to weld — 50/100, worse than 77% of stainless steel grades
CG8M-AC properties
Typical room-temperature values for CG8M-AC; 22 are specific to this condition. Other listed values are CG8M reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
CG8M-AC has a density of 7.98 g/cm³ (0.288 lb/in³), heavier than 85% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Mechanical16
CG8M-AC has a yield strength of 285 MPa (41.3 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 74% of stainless steel grades. Elongation at break is 28% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
CG8M-AC is rated for continuous service to 550°C (1,022 °F). It conducts heat at 14 W/m·K (8.09 BTU/hr·ft·°F), worse than 80% of stainless steel grades. Thermal expansion is 16 µm/m·K (8.89 µin/in·°F).
Electrical3
CG8M-AC conducts electricity at 2 % IACS, worse than 77% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 71% of stainless steel grades.
Sustainability4
Producing a kilogram of CG8M-AC takes about 55 MJ of energy and emits 4.5 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 70%.
Manufacturability8
CG8M-AC's machinability is poor (29/100, worse than 76% of stainless steel grades); weldability fair (50/100); formability poor (18/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CG8M-AC
Is CG8M easy to machine?
Gummy and work-hardening: use rigid setups, positive-rake carbide, 60–110 m/min, heavy feeds and flood coolant, avoid dwelling to prevent glazing.
Can CG8M be welded?
Readily welded with ER317L/E317L-15 filler (GTAW/SMAW); keep interpass temperature low and use low-carbon filler to limit sensitization — no post-weld heat treatment needed for thin sections, re-solution treat heavy repairs.
Can CG8M be formed, bent or molded?
Sand or investment cast with generous risers and chills — wide freezing range and 2.0–2.5% solidification shrinkage promote centerline microporosity; solution treat ≥1040 °C and water quench.
What surface finishes work on CG8M?
Pickle and passivate (ASTM A967) or electropolish for chemical service; shot-blast/grind gate marks first — casting skin porosity limits mirror polish, and no anodizing applies.
CG8M 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 |
|---|---|---|
| C | ≤ 0.08 | 0.06 |
| Mn | ≤ 1.5 | 1 |
| Si | ≤ 1.5 | 1.2 |
| P | ≤ 0.04 | 0.03 |
| S | ≤ 0.04 | 0.02 |
| Cr | 18 – 21 | 19.5 |
| Ni | 9 – 13 | 11 |
| Mo | 3 – 4 | 3.5 |
| Fe | balance | — |
CG8M-AC — frequently asked
What is CG8M-AC used for?
CG8M-AC is typically used for pulp and paper process equipment, chemical process valves and flue gas desulfurization components. In short: cast 317 equivalent; higher pitting resistance than CF8M; chemical and pulp service.
What is the yield strength of CG8M-AC?
CG8M-AC has a typical yield strength of 285 MPa (41.3 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 74% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is CG8M-AC easy to machine?
Not especially — machinability is rated poor (29/100, worse than 76% of stainless steel grades). Gummy and work-hardening: use rigid setups, positive-rake carbide, 60–110 m/min, heavy feeds and flood coolant, avoid dwelling to prevent glazing.
Can CG8M-AC be welded?
With care — weldability is rated fair (50/100). Readily welded with ER317L/E317L-15 filler (GTAW/SMAW); keep interpass temperature low and use low-carbon filler to limit sensitization — no post-weld heat treatment needed for thin sections, re-solution treat heavy repairs.
What surface finishes work on CG8M-AC?
Pickle and passivate (ASTM A967) or electropolish for chemical service; shot-blast/grind gate marks first — casting skin porosity limits mirror polish, and no anodizing applies.
Can CG8M-AC be formed, bent or molded?
Sand or investment cast with generous risers and chills — wide freezing range and 2.0–2.5% solidification shrinkage promote centerline microporosity; solution treat ≥1040 °C and water quench.
What is the maximum service temperature of CG8M-AC?
CG8M-AC is rated for continuous use to about 550°C (1,022 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CG8M-ST and CG8M ST-HIP?
ST is the default condition — standard supply condition for all CG8M castings — maximum corrosion resistance and ductility. ST-HIP: choose for thick-section or fatigue-critical castings where internal microporosity must be closed. Yield strength is 290 MPa in ST versus 300 MPa in ST-HIP.
Sources
- ASTM A743/A743M — Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application — ASTM International (2019)
- ASTM A744/A744M — Castings, Iron-Chromium-Nickel, Corrosion Resistant, for Severe Service — ASTM International (2021)
- ASTM A351/A351M — Castings, Austenitic, for Pressure-Containing Parts — ASTM International (2018)
- 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)
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.