Stainless Steel CH20
UNS J93402 · JIS SCS17
CH20 is a 25Cr-12Ni cast austenitic stainless steel, the casting counterpart of wrought 309, supplied under ASTM A351/A743 (UNS J93402, JIS SCS17).
Reference datasheet — CH20 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the SA condition
CH20 tempers and conditions
CH20 is supplied in 3 conditions, soft to hard. SA is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SADefault Solution annealed | Standard supply condition for ASTM A743/A744 CH20 castings; carbides dissolved for best corrosion resistance and ductility. | 240 | 530 | 38 | 165 HB | — |
As fabricated | Used for non-critical or purely high-temperature-oxidation parts where corrosion service does not require carbide dissolution. | 255 | 505 | 20 | 180 HB | 2.2 % IACS |
Centrifugally cast, solution annealed | Choose for tubes, rings and sleeves where the dense, directionally solidified centrifugal structure raises soundness and strength. | 255 | 560 | 35 | 170 HB | 2.2 % IACS |
What is CH20?
CH20 is a 25Cr-12Ni cast austenitic stainless steel, the casting counterpart of wrought 309, supplied under ASTM A351/A743 (UNS J93402, JIS SCS17). It is specified for oxidation resistance in furnace atmospheres up to 1000 °C; solution-annealed sand, investment and centrifugal castings give 240 MPa yield, 530 MPa tensile, 38 % elongation and about 165 HB (85 HRB). Aqueous corrosion resistance is only moderate and the carbon content leaves as-welded parts sensitive to grain-boundary carbides, so solution anneal after welding for corrosion service. For continuous service above 1000 °C, CK20 is the nearest alternative. CH20 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). CH20 has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 96% of stainless steel grades. Elongation at break is 38% and the elastic modulus is 193 GPa (28 Msi).
What is CH20 used for?
- Furnace and kiln components
- Heat treatment fixtures
- High-temperature valve bodies
Advantages
- High service temperature — 1,000°C (1,832 °F), better than 88% of stainless steel grades
Limitations
- Low strength — 240 MPa (34.8 ksi), worse than 96% of stainless steel grades
- Limited formability — 15/100, worse than 91% of stainless steel grades
- Hard to polish — 55/100, worse than 89% of stainless steel grades
CH20 properties
Typical room-temperature values for CH20-SA; bars are the position among stainless steel grades.
Physical3
CH20 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).
Mechanical13
CH20 has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 96% of stainless steel grades. Elongation at break is 38% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
CH20 is rated for continuous service to 1,000°C (1,832 °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 µm/m·K (8.33 µin/in·°F).
Electrical3
CH20 conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 63% of stainless steel grades.
Sustainability4
Producing a kilogram of CH20 takes about 55 MJ of energy and emits 4.5 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 75%.
Manufacturability7
CH20's machinability is fair (35/100, better than 51% of stainless steel grades); weldability good (55/100); formability poor (15/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. CH20 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with CH20
Is CH20 easy to machine?
Machine like 309: rigid setups, sharp positive-rake carbide, heavy depth of cut and low speed (~40–70 m/min) with flood coolant to avoid work hardening and glazing.
Can CH20 be welded?
GTAW/SMAW with 309/CH20 matching filler; keep interpass low, and solution anneal after welding for corrosion service to restore carbide-free grain boundaries.
Can CH20 be formed, bent or molded?
Sand, investment or centrifugal casting; wide freezing range demands generous risering and chills, and 1040–1090 °C solution anneal plus water quench after cleaning.
CH20 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 C vs CF8 raises hot strength | ≤ 0.2 | 0.15 |
| Mn | ≤ 1.5 | 1 |
| Si | ≤ 2 | 1.2 |
| P | ≤ 0.04 | |
| S | ≤ 0.04 | |
| Cr | 22 – 26 | 24 |
| Ni | 12 – 15 | 13.5 |
| Moresidual only, not intentionally added | ≤ 0.5 | |
| Fe | balance |
What surface finishes work on CH20?
Pickle/passivate (nitric or nitric-HF) after heat treatment to remove scale; grinds and polishes to a satin finish, though casting porosity limits mirror quality.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Organic Coating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel CH20 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- J93402
- JIS
- SCS17
- Also called
- Cast 309
How much does CH20 cost?
CH20 is a premium-cost stainless steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
CH20 — frequently asked
What is CH20 used for?
CH20 is typically used for furnace and kiln components, heat treatment fixtures and high-temperature valve bodies. In short: cast 309 equivalent; oxidation service to 1000 °C; economical heat-resistant casting.
What is the yield strength of CH20?
CH20 has a typical yield strength of 240 MPa (34.8 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 96% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is CH20 easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% of stainless steel grades). Machine like 309: rigid setups, sharp positive-rake carbide, heavy depth of cut and low speed (~40–70 m/min) with flood coolant to avoid work hardening and glazing.
Can CH20 be welded?
Yes — weldability is rated good (55/100). GTAW/SMAW with 309/CH20 matching filler; keep interpass low, and solution anneal after welding for corrosion service to restore carbide-free grain boundaries.
What surface finishes work on CH20?
Pickle/passivate (nitric or nitric-HF) after heat treatment to remove scale; grinds and polishes to a satin finish, though casting porosity limits mirror quality.
Can CH20 be formed, bent or molded?
Sand, investment or centrifugal casting; wide freezing range demands generous risering and chills, and 1040–1090 °C solution anneal plus water quench after cleaning.
What is the maximum service temperature of CH20?
CH20 is rated for continuous use to about 1,000°C (1,832 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CH20-SA and CH20-F?
SA is the default condition — standard supply condition for ASTM A743/A744 CH20 castings; carbides dissolved for best corrosion resistance and ductility. F: used for non-critical or purely high-temperature-oxidation parts where corrosion service does not require carbide dissolution. Yield strength is 240 MPa in SA versus 255 MPa in F.
How much does CH20 cost?
CH20 is a premium-cost stainless steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
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)
- SAE/ASTM UNS J93402 designation data (Metals & Alloys in the Unified Numbering System) — SAE/ASTM (2017)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (Cast Stainless Steels) — ASM International (1990)
- Steel Castings Handbook, 6th ed. (High Alloy Data Sheets, Corrosion Series) — Steel Founders' Society of America (1995)
- JIS G 5121 SCS17 cast stainless steel — Japanese Standards Association (2003)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.