Stainless Steel CA40F N+T
Heat-treated state · default condition
ASTM CA40F · UNS J91154
N+T = normalized and tempered
Standard ASTM A743 supply condition: best balance of strength, ductility and machinability for valve and pump castings.
Values for the N+T condition
Other CA40F tempers and conditions
CA40F is listed in 4 conditions; see the grade overview at CA40F.
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+TDefaultThis page 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 N+T?
CA40F N+T is CA40F heat treated to N+T — standard ASTM A743 supply condition: best balance of strength, ductility and machinability for valve and pump castings. CA40F N+T 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). CA40F N+T 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).
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 N+T properties
Typical room-temperature values for CA40F N+T; 13 are specific to this condition. Other listed values are CA40F reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
CA40F N+T 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 N+T 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 N+T 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 N+T 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 N+T 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 N+T'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. Confirm any required mill or lot documentation when quoting.
Working with CA40F N+T
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.
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.
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 | — |
CA40F N+T — frequently asked
What is CA40F N+T used for?
CA40F N+T 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 N+T?
CA40F N+T 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 N+T 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 N+T 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 N+T?
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 N+T 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 N+T?
CA40F N+T 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.