Steel CA6NM N+T
Heat-treated state · default condition
UNS J91540 · ASTM A487 Gr. CA6NM, A743 CA6NM · EN GX4CrNi13-4, 1.4317 · GB ZG06Cr13Ni4
N+T = normalized and tempered
Standard commercial condition for hydro turbine and pump castings — best all-round balance of 550 MPa+ yield, high toughness and ≤285 HB for machining.
Values for the N+T condition
Other CA6NM tempers and conditions
CA6NM is listed in 6 conditions; see the grade overview at CA6NM.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Double tempered (e.g. 665 °C + 600 °C) for maximum toughness | Choose for large hydro runners, cold-climate or fracture-critical castings where low-temperature CVN and stable retained/reverted austenite matter more than peak strength. | 620 | 790 | 22 | 23 HRC | — |
ASTM A487 Gr. CA6NM Class A | Pressure-containing castings (valves, pump casings) certified to A487 Class A minimums with impact testing. | 660 | 830 | 18 | 25 HRC | 2.3 % IACS |
N+TDefaultThis page Normalized and tempered | Standard commercial condition for hydro turbine and pump castings — best all-round balance of 550 MPa+ yield, high toughness and ≤285 HB for machining. | 690 | 830 | 20 | 25 HRC | — |
ASTM A487 Gr. CA6NM Class B | Lower tempering temperature for higher guaranteed yield where thick-section strength governs; ductility and toughness are traded off. | 750 | 900 | 15 | 30 HRC | 2.3 % IACS |
Spheroidize annealed | Foundry-shipped condition for parts that will be austenitized and tempered by the buyer — brittle untempered martensite, not for service. | 800 | 1,000 | 8 | 37 HRC | 2.2 % IACS |
Q&T high strength | Pump impellers and wear-critical parts needing extra cavitation/erosion resistance; keep out of the ~450–550 °C embrittlement window and expect lower CVN. | 850 | 1,000 | 14 | 32 HRC | 2.3 % IACS |
What is CA6NM N+T?
CA6NM N+T is CA6NM heat treated to N+T — standard commercial condition for hydro turbine and pump castings — best all-round balance of 550 MPa+ yield, high toughness and ≤285 HB for machining. CA6NM N+T has a yield strength of 690 MPa (100 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 80% of steel grades. Elongation at break is 20% and the elastic modulus is 200 GPa (29 Msi). CA6NM N+T has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 95% of steel grades. It melts at 1,425°C (2,597 °F).
Advantages
- Good corrosion resistance — 55/100, better than 99% of steel grades
- Tough — resists crack growth — 150 MPa·√m (136.5 ksi·√in), better than 96% of steel grades
- High service temperature — 450°C (842 °F), better than 86% of steel grades
- High strength — 690 MPa (100 ksi), better than 80% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Low electrical conductivity — 2.3 % IACS, worse than 98% of steel grades
- High embodied carbon — 3.5 kg CO₂/kg, worse than 93% of steel grades
- Poor heat conductor — 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 88% of steel grades
- Limited formability — 15/100, worse than 87% of steel grades
- Difficult to machine — 40/100, worse than 77% of steel grades
CA6NM N+T properties
Typical room-temperature values for CA6NM N+T; 10 are specific to this condition. Other listed values are CA6NM reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
CA6NM N+T has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 95% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
CA6NM N+T has a yield strength of 690 MPa (100 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 80% of steel grades. Elongation at break is 20% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
CA6NM N+T is rated for continuous service to 450°C (842 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 88% of steel grades. Thermal expansion is 10.5 µm/m·K (5.83 µin/in·°F).
Electrical3
CA6NM N+T conducts electricity at 2.3 % IACS, worse than 98% of steel grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), better than 99% of steel grades.
Sustainability4
Producing a kilogram of CA6NM N+T takes about 40 MJ of energy and emits 3.5 kg of CO₂ — more than 91% of steel grades. Typical recycled content is 70%.
Manufacturability7
CA6NM N+T's machinability is fair (40/100, worse than 77% of steel grades); weldability very good (70/100); formability poor (15/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CA6NM N+T
Is CA6NM easy to machine?
Machine after tempering at 230–285 HB using rigid setups, positive-rake carbide and heavy feeds to cut under the work-hardened layer; low speeds with copious coolant.
Can CA6NM be welded?
Very good for a martensitic stainless — use E410NiMo/ER410NiMo filler, preheat 100–150 °C, interpass <150 °C and PWHT/temper at 595–620 °C for major weld repairs.
Can CA6NM be formed, bent or molded?
Sand or investment cast only; feed heavy sections generously and always austenitize+temper the casting — cold forming is not applicable.
What surface finishes work on CA6NM?
Passivate or pickle after machining to restore the chromium oxide film; polishes to a fine finish, and hard/thermal-spray coatings are common on cavitation zones.
CA6NM 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 |
|---|---|---|
| Clow carbon is key to weldability | ≤ 0.06 | 0.04 |
| Mn | ≤ 1 | 0.7 |
| Si | ≤ 1 | 0.6 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Cr | 11.5 – 14 | 12.8 |
| Ni | 3.5 – 4.5 | 4 |
| Mo | 0.4 – 1 | 0.6 |
| Fe | balance | — |
CA6NM N+T — frequently asked
What is CA6NM N+T used for?
CA6NM N+T is typically used for hydraulic turbine runners, pump casings and impellers and valve bodies in erosive service. In short: toughest martensitic stainless casting; weldable 13Cr-4Ni grade; cavitation-resistant turbine steel.
What is the yield strength of CA6NM N+T?
CA6NM N+T has a typical yield strength of 690 MPa (100 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 80% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is CA6NM N+T easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% of steel grades). Machine after tempering at 230–285 HB using rigid setups, positive-rake carbide and heavy feeds to cut under the work-hardened layer; low speeds with copious coolant.
Can CA6NM N+T be welded?
Yes — weldability is rated very good (70/100). Very good for a martensitic stainless — use E410NiMo/ER410NiMo filler, preheat 100–150 °C, interpass <150 °C and PWHT/temper at 595–620 °C for major weld repairs.
What surface finishes work on CA6NM N+T?
Passivate or pickle after machining to restore the chromium oxide film; polishes to a fine finish, and hard/thermal-spray coatings are common on cavitation zones.
Can CA6NM N+T be formed, bent or molded?
Sand or investment cast only; feed heavy sections generously and always austenitize+temper the casting — cold forming is not applicable.
What is the maximum service temperature of CA6NM N+T?
CA6NM N+T is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CA6NM N+T and CA6NM QT-HS?
N+T is the default condition — standard commercial condition for hydro turbine and pump castings — best all-round balance of 550 MPa+ yield, high toughness and ≤285 HB for machining. QT-HS: pump impellers and wear-critical parts needing extra cavitation/erosion resistance; keep out of the ~450–550 °C embrittlement window and expect lower CVN. Yield strength is 690 MPa in N+T versus 850 MPa in QT-HS.
Sources
- ASTM A743/A743M — Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application — ASTM International (2019)
- ASTM A487/A487M — Steel Castings Suitable for Pressure Service — ASTM International (2020)
- EN 10283 — Corrosion resistant steel castings (GX4CrNi13-4, 1.4317) — CEN (2010)
- GB/T 6967 / GB/T 2100 (ZG06Cr13Ni4Mo) — SAC (2009)
- Steel Castings Handbook, 6th ed. — Steel Founders' Society of America / ASM (1995)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- NACE MR0175 / ISO 15156-3 materials for H2S-containing environments — NACE/ISO (2020)
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.