Stainless Steel CA40F
ASTM CA40F · UNS J91154
CA40F is the sulfur-added free-machining variant of CA40 (UNS J91154, ASTM A743 Gr.
Reference datasheet — CA40F 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 N+T condition
CA40F tempers and conditions
CA40F is supplied in 4 conditions, soft to hard. N+T is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Pick when the casting must be extensively machined or drilled before final hardening; softest, lowest-strength condition. | 420 | 650 | 20 | 190 HB | — |
N+TDefault Normalized and tempered | Standard ASTM A743 supply condition: best balance of strength, ductility and machinability for valve and pump castings. | 570 | 760 | 14 | 22 HRC | — |
As fabricated | Raw casting condition, hard and brittle untempered martensite — used only as a starting point before heat treatment, never for service. | 650 | 900 | 4 | 43 HRC | — |
Oil/air hardened, tempered ~300–400 °C | Choose for wear surfaces, seats and bushings where hardness matters more than toughness or corrosion margin (outside the A743 269 HB cap). | 950 | 1,200 | 7 | 37 HRC | — |
What is CA40F?
CA40F is the sulfur-added free-machining variant of CA40 (UNS J91154, ASTM A743 Gr. CA40F), retaining martensitic hardenability while cutting far more easily. Typical properties are 570 MPa yield, 760 MPa tensile, 14% elongation and 240 HB (22 HRC), with service to 620 °C, and it is specified for castings that need heavy secondary machining such as valve components and pump shafts. The 0.2-0.4% sulfur lowers corrosion resistance (score 35) and makes the alloy effectively unweldable for pressure service; use CA40 where welding or maximum corrosion resistance is required. CA40F has a density of 7.61 g/cm³ (0.275 lb/in³), lighter than 96% of stainless steel grades. It melts at 1,450°C (2,642 °F). CA40F has a yield strength of 570 MPa (82.7 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 85% of stainless steel grades. Elongation at break is 14% and the elastic modulus is 200 GPa (29 Msi).
What is CA40F used for?
- Machined valve components
- Fittings requiring heavy machining
- Pump shafts
Advantages
- Easy to machine — 58/100, better than 97% of stainless steel grades
- High electrical conductivity — 3 % IACS, better than 95% of stainless steel grades
- High strength — 570 MPa (82.7 ksi), better than 85% of stainless steel grades
- Conducts heat well — 24.2 W/m·K (14 BTU/hr·ft·°F), better than 83% of stainless steel grades
Limitations
- Limited formability — 5/100, worse than 99% of stainless steel grades
- Difficult to weld — 15/100, worse than 98% of stainless steel grades
- Needs corrosion protection — 35/100, worse than 97% of stainless steel grades
- Hard to polish — 45/100, worse than 96% of stainless steel grades
- Low fracture toughness — 50 MPa·√m (45.5 ksi·√in), worse than 92% of stainless steel grades
CA40F properties
Typical room-temperature values for CA40F-N+T; bars are the position among stainless steel grades.
Physical3
CA40F has a density of 7.61 g/cm³ (0.275 lb/in³), lighter than 96% of stainless steel grades. It melts at 1,450°C (2,642 °F).
Mechanical16
CA40F has a yield strength of 570 MPa (82.7 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 85% of stainless steel grades. Elongation at break is 14% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
CA40F is rated for continuous service to 620°C (1,148 °F). It conducts heat at 24.2 W/m·K (14 BTU/hr·ft·°F), better than 83% of stainless steel grades. Thermal expansion is 10.3 µm/m·K (5.72 µin/in·°F).
Electrical3
CA40F conducts electricity at 3 % IACS, better than 95% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (35/100), worse than 97% of stainless steel grades.
Sustainability4
Producing a kilogram of CA40F takes about 53 MJ of energy and emits 4.3 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 75%.
Manufacturability7
CA40F's machinability is good (58/100, better than 97% of stainless steel grades); weldability poor (15/100); formability not recommended (5/100).
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. CA40F is highlighted; hover a dot for its name, or open the interactive family chart.
Working with CA40F
Is CA40F easy to machine?
The best-machining martensitic cast stainless — run it annealed or at ≤269 HB with sharp carbide tools, positive rake and generous feed; the MnS stringers break chips and cut tool wear roughly 40 % versus CA40.
Can CA40F be welded?
Effectively unweldable for pressure service: high carbon plus 0.2–0.4 % S invites hot cracking and underbead cracks; if repair is unavoidable use 309/410NiMo filler with 250–320 °C preheat and immediate post-weld temper.
Can CA40F be formed, bent or molded?
Supplied only as castings; keep sections uniform, feed heavy junctions with risers, and always austenitize + temper before machining critical dimensions to avoid distortion.
CA40F 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 |
|---|---|---|
| Cgives martensitic hardenability | 0.2 – 0.4 | 0.3 |
| Mncombines with S as MnS chip breakers | ≤ 1 | 0.7 |
| Si | ≤ 1.5 | 0.8 |
| Cr | 11.5 – 14 | 12.8 |
| Ni | ≤ 1 | 0.5 |
| Moresidual, not intentionally added | ≤ 0.5 | 0.2 |
| Sintentional free-machining addition | 0.2 – 0.4 | 0.3 |
| P | ≤ 0.04 | 0.03 |
| Fe | balance |
What surface finishes work on CA40F?
Passivate in nitric or citric acid after machining to dissolve smeared sulfides; hard chrome, nitriding or PVD improve wear life, but expect a duller polish than CA15 because sulfide inclusions pull out.
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 CA40F in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- J91154
- ASTM
- A743 Gr. CA40F
How much does CA40F cost?
CA40F 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.
CA40F — frequently asked
What is CA40F used for?
CA40F is typically used for machined valve components, fittings requiring heavy machining and pump shafts. In short: best-machining cast martensitic; free-machining CA40; not for welded assemblies.
What is the yield strength of CA40F?
CA40F has a typical yield strength of 570 MPa (82.7 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 85% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is CA40F easy to machine?
Reasonably — machinability is rated good (58/100, better than 97% of stainless steel grades). The best-machining martensitic cast stainless — run it annealed or at ≤269 HB with sharp carbide tools, positive rake and generous feed; the MnS stringers break chips and cut tool wear roughly 40 % versus CA40.
Can CA40F be welded?
Not readily — weldability is rated poor (15/100). Effectively unweldable for pressure service: high carbon plus 0.2–0.4 % S invites hot cracking and underbead cracks; if repair is unavoidable use 309/410NiMo filler with 250–320 °C preheat and immediate post-weld temper.
What surface finishes work on CA40F?
Passivate in nitric or citric acid after machining to dissolve smeared sulfides; hard chrome, nitriding or PVD improve wear life, but expect a duller polish than CA15 because sulfide inclusions pull out.
Can CA40F be formed, bent or molded?
Supplied only as castings; keep sections uniform, feed heavy junctions with risers, and always austenitize + temper before machining critical dimensions to avoid distortion.
What is the maximum service temperature of CA40F?
CA40F is rated for continuous use to about 620°C (1,148 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CA40F N+T and CA40F-A?
N+T is the default condition — standard ASTM A743 supply condition: best balance of strength, ductility and machinability for valve and pump castings. A: pick when the casting must be extensively machined or drilled before final hardening; softest, lowest-strength condition. Yield strength is 570 MPa in N+T versus 420 MPa in A.
How much does CA40F cost?
CA40F 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)
- SAE J405 / Unified Numbering System UNS J91154 — SAE International / ASTM (2020)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys (cast stainless steels) — ASM International (1990)
- ASM Handbook Vol. 13B: Corrosion — Materials — ASM International (2005)
- Steel Castings Handbook, 6th ed. — Steel Founders' Society of America / ASM (1995)
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.