Stainless Steel CH20-F (As fabricated)
Temper
UNS J93402 · JIS SCS17
Used for non-critical or purely high-temperature-oxidation parts where corrosion service does not require carbide dissolution.
Values for the F condition
Other CH20 tempers and conditions
CH20 is listed in 3 conditions; see the grade overview at CH20.
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 | — |
FThis page 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-F?
CH20-F is CH20 in the F temper — used for non-critical or purely high-temperature-oxidation parts where corrosion service does not require carbide dissolution. CH20-F has a yield strength of 255 MPa (37 ksi) and a tensile strength of 505 MPa (73.2 ksi) — weaker than 87% of stainless steel grades. Elongation at break is 20% and the elastic modulus is 193 GPa (28 Msi). CH20-F 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; F is available on request or by drawing note.
Advantages
- High service temperature — 1,000°C (1,832 °F), better than 88% of stainless steel grades
Limitations
- Limited formability — 8/100, worse than 97% of stainless steel grades
- Hard to polish — 55/100, worse than 89% of stainless steel grades
- Low strength — 255 MPa (37 ksi), worse than 87% of stainless steel grades
- Limited ductility — 20%, worse than 79% of stainless steel grades
- Difficult to weld — 45/100, worse than 79% of stainless steel grades
CH20-F properties
Typical room-temperature values for CH20-F; 22 are specific to this condition. Other listed values are CH20 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
CH20-F 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-F has a yield strength of 255 MPa (37 ksi) and a tensile strength of 505 MPa (73.2 ksi) — weaker than 87% of stainless steel grades. Elongation at break is 20% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
CH20-F is rated for continuous service to 1,000°C (1,832 °F). It conducts heat at 14.2 W/m·K (8.2 BTU/hr·ft·°F), worse than 76% of stainless steel grades. Thermal expansion is 15 µm/m·K (8.33 µin/in·°F).
Electrical3
CH20-F conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 71% of stainless steel grades.
Sustainability4
Producing a kilogram of CH20-F 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-F's machinability is poor (30/100, worse than 70% of stainless steel grades); weldability fair (45/100); formability not recommended (8/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CH20-F
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.
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.
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 | — |
CH20-F — frequently asked
What is CH20-F used for?
CH20-F 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-F?
CH20-F has a typical yield strength of 255 MPa (37 ksi) and a tensile strength of 505 MPa (73.2 ksi) — weaker than 87% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is CH20-F easy to machine?
Not especially — machinability is rated poor (30/100, worse than 70% 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-F be welded?
With care — weldability is rated fair (45/100). 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-F?
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-F 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-F?
CH20-F 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.