Stainless Steel CK35MN-AC (Spheroidize annealed)
Heat-treated state · default condition
ASTM CK35MN
Standard supply condition for heat-resistant service — carbides in the as-cast network actually aid creep strength.
Values for the AC condition
Other CK35MN tempers and conditions
CK35MN is listed in 4 conditions; see the grade overview at CK35MN.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Choose when maximum ductility, toughness and aqueous corrosion resistance are needed before service; dissolves the as-cast carbide network. | 230 | 480 | 38 | 170 HB | 2 % IACS |
Statically sand/investment cast shape | Standard route for valve bodies, grates, fixtures and complex furnace hardware where section thickness varies. | 245 | 495 | 30 | 183 HB | 2 % IACS |
ACDefaultThis page Spheroidize annealed | Standard supply condition for heat-resistant service — carbides in the as-cast network actually aid creep strength. | 250 | 500 | 30 | 185 HB | 2 % IACS |
Stress relieved | Use on large or welded castings to relieve residual stress and reduce distortion before machining; does not restore ductility. | 250 | 495 | 26 | 187 HB | 2.1 % IACS |
What is CK35MN-AC?
CK35MN-AC is CK35MN heat treated to AC — standard supply condition for heat-resistant service — carbides in the as-cast network actually aid creep strength. CK35MN-AC 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 30% and the elastic modulus is 193 GPa (28 Msi). CK35MN-AC has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Advantages
- High service temperature — 1,050°C (1,922 °F), better than 91% of stainless steel grades
Limitations
- Limited formability — 10/100, worse than 95% of stainless steel grades
- Low strength — 250 MPa (36.3 ksi), worse than 91% of stainless steel grades
- Hard to polish — 55/100, worse than 89% of stainless steel grades
- Difficult to weld — 40/100, worse than 83% of stainless steel grades
- Low fracture toughness — 85 MPa·√m (77.4 ksi·√in), worse than 77% of stainless steel grades
CK35MN-AC properties
Typical room-temperature values for CK35MN-AC; 21 are specific to this condition. Other listed values are CK35MN reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
CK35MN-AC has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Mechanical15
CK35MN-AC 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 30% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
CK35MN-AC is rated for continuous service to 1,050°C (1,922 °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 15.9 µm/m·K (8.83 µin/in·°F).
Electrical3
CK35MN-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 CK35MN-AC takes about 60 MJ of energy and emits 4.5 kg of CO₂ — more than 70% of stainless steel grades. Typical recycled content is 65%.
Manufacturability8
CK35MN-AC's machinability is poor (28/100, worse than 79% of stainless steel grades); weldability fair (40/100); formability not recommended (10/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CK35MN-AC
Is CK35MN easy to machine?
Rigid setups, low speed with heavy positive feed, sharp carbide or ceramic tooling and flood coolant; the work-hardening austenite plus interdendritic carbides cause rapid edge wear, so avoid dwelling and interrupted light cuts.
Can CK35MN be welded?
Weldable with matching 25Cr-20Ni (ER310/E310-type) filler using low heat input, small stringer beads and interpass temperature control; fully austenitic ferrite-free weld metal is hot-crack sensitive and the high-carbon base is prone to HAZ carbide precipitation.
Can CK35MN be formed, bent or molded?
A casting grade only — not intended for cold forming; design generous fillets, uniform sections and adequate risers, allow ~2 % solidification shrinkage and avoid hot-tear-prone sharp corners.
What surface finishes work on CK35MN?
Grit blast plus pickle/passivate to remove casting scale; shot-peening or grinding improves fatigue, and aluminizing or diffusion coating extends life above 1000 °C in sulphur-bearing gas.
CK35MN 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 |
|---|---|---|
| Chigh carbon for creep strength; verify range against the current ASTM A351/A743 edition | 0.25 – 0.35 | 0.3 |
| Mnmanganese-alloyed feature of this grade (partial Ni substitute / austenite stabilizer) | 1.5 – 4 | 2.5 |
| Si | ≤ 1.5 | 1 |
| CrCK-family chromium level, as CK20 | 23 – 27 | 25 |
| Ni | 18 – 22 | 20 |
| Moresidual only | ≤ 0.5 | 0.2 |
| Nnitrogen may be specified to strengthen the austenite | ≤ 0.2 | 0.1 |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Fe | balance | — |
CK35MN-AC — frequently asked
What is CK35MN-AC used for?
CK35MN-AC is typically used for high-temperature furnace castings, heat-resistant process equipment, heat treatment fixtures and trays, furnace rollers and rails, radiant tube and burner parts and kiln fittings. In short: manganese-alloyed CK20 substitute; lower nickel content; 1050 °C oxidation service.
What is the yield strength of CK35MN-AC?
CK35MN-AC 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 4 listed tempers.
Is CK35MN-AC easy to machine?
Not especially — machinability is rated poor (28/100, worse than 79% of stainless steel grades). Rigid setups, low speed with heavy positive feed, sharp carbide or ceramic tooling and flood coolant; the work-hardening austenite plus interdendritic carbides cause rapid edge wear, so avoid dwelling and interrupted light cuts.
Can CK35MN-AC be welded?
With care — weldability is rated fair (40/100). Weldable with matching 25Cr-20Ni (ER310/E310-type) filler using low heat input, small stringer beads and interpass temperature control; fully austenitic ferrite-free weld metal is hot-crack sensitive and the high-carbon base is prone to HAZ carbide precipitation.
What surface finishes work on CK35MN-AC?
Grit blast plus pickle/passivate to remove casting scale; shot-peening or grinding improves fatigue, and aluminizing or diffusion coating extends life above 1000 °C in sulphur-bearing gas.
Can CK35MN-AC be formed, bent or molded?
A casting grade only — not intended for cold forming; design generous fillets, uniform sections and adequate risers, allow ~2 % solidification shrinkage and avoid hot-tear-prone sharp corners.
What is the maximum service temperature of CK35MN-AC?
CK35MN-AC is rated for continuous use to about 1,050°C (1,922 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CK35MN-AC and CK35MN-SA?
AC is the default condition — standard supply condition for heat-resistant service — carbides in the as-cast network actually aid creep strength. SA: choose when maximum ductility, toughness and aqueous corrosion resistance are needed before service; dissolves the as-cast carbide network. Yield strength is 250 MPa in AC versus 230 MPa in SA.
Sources
- ASTM A351/A351M — Castings, Austenitic, for Pressure-Containing Parts — ASTM International (2018)
- ASTM A743/A743M — Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application — ASTM International (2019)
- High Alloy Data Sheets, Heat Series (CK-type / HK-type alloys) — Steel Founders' Society of America (2004)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- 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.