Stainless Steel CA6N N+T-HT
Heat-treated state
ASTM CA6N · UNS J91650
Pick when maximum impact toughness, lower hardness for machining, or NACE-type hardness limits matter more than peak strength.
Values for the N+T-HT condition
Other CA6N tempers and conditions
CA6N is listed in 5 conditions; see the grade overview at CA6N.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest condition, used between rough machining and final heat treatment or before major weld repair. | 560 | 760 | 24 | 18 HRC | 2.3 % IACS |
N+T-HTThis page N+T | Pick when maximum impact toughness, lower hardness for machining, or NACE-type hardness limits matter more than peak strength. | 720 | 860 | 22 | 24 HRC | — |
As fabricated | Foundry as-cast state only; brittle untempered martensite that must be normalized and tempered before use. | 900 | 1,100 | 9 | 37 HRC | 2.1 % IACS |
N+TDefault Normalized and tempered | Standard ASTM A743 CA6N supply condition: maximum strength with useful toughness for pump/valve pressure parts. | 930 | 1,020 | 19 | 31 HRC | — |
hot isostatically pressed, then normalized and tempered | For critical fatigue- or pressure-rated castings where internal porosity must be closed; same strength as N+T with better ductility and fatigue scatter. | 940 | 1,030 | 22 | 31 HRC | 2.2 % IACS |
What is CA6N N+T-HT?
CA6N N+T-HT is CA6N heat treated to N+T-HT — pick when maximum impact toughness, lower hardness for machining, or NACE-type hardness limits matter more than peak strength. CA6N N+T-HT has a yield strength of 720 MPa (104 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 93% of stainless steel grades. Elongation at break is 22% and the elastic modulus is 200 GPa (29 Msi). CA6N N+T-HT 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). N+T is the default condition FabDigit quotes; N+T-HT is available on request or by drawing note.
Advantages
- High strength — 720 MPa (104 ksi), better than 93% of stainless steel grades
- Conducts heat well — 25 W/m·K (14.4 BTU/hr·ft·°F), better than 93% of stainless steel grades
- Low embodied carbon — 3.6 kg CO₂/kg, better than 83% of stainless steel grades
Limitations
- Limited formability — 15/100, worse than 91% of stainless steel grades
- Limited ductility — 22%, worse than 75% of stainless steel grades
CA6N N+T-HT properties
Typical room-temperature values for CA6N N+T-HT; 11 are specific to this condition. Other listed values are CA6N reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
CA6N N+T-HT 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).
Mechanical16
CA6N N+T-HT has a yield strength of 720 MPa (104 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 93% of stainless steel grades. Elongation at break is 22% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
CA6N N+T-HT is rated for continuous service to 450°C (842 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), better than 93% of stainless steel grades. Thermal expansion is 10.6 µm/m·K (5.89 µin/in·°F).
Electrical3
CA6N N+T-HT 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 CA6N N+T-HT takes about 53 MJ of energy and emits 3.6 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 75%.
Manufacturability8
CA6N N+T-HT's machinability is fair (40/100, better than 72% of stainless steel grades); weldability good (62/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CA6N N+T-HT
Is CA6N easy to machine?
Machine in the annealed or high-tempered state with rigid setups, sharp carbide inserts, positive rake and heavy flood coolant; work-hardens and gums up at low speed like other 12Cr martensitics.
Can CA6N be welded?
Weldable with matching low-C 12Cr-Ni or 410NiMo filler; preheat 100–150 °C, keep interpass below ~150 °C, and post-weld temper at 595–620 °C to restore toughness — never leave weld metal untempered.
Can CA6N be formed, bent or molded?
Casting alloy only: good fluidity for pumps, valve bodies and hydro turbine runners, but design generous risers and radii to avoid shrinkage porosity and hot tears; full normalize-and-temper after any weld repair.
What surface finishes work on CA6N?
Passivate per ASTM A967 or electropolish for corrosion service; takes a good mechanical polish, and can be hard chrome plated or nitrided below the tempering temperature.
CA6N 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 keeps martensite tough and weldable | ≤ 0.06 | 0.04 |
| Mn | ≤ 0.5 | 0.35 |
| Si | ≤ 1 | 0.6 |
| P | ≤ 0.02 | 0.02 |
| S | ≤ 0.02 | 0.01 |
| Cr | 10.5 – 12.5 | 11.5 |
| Nihigh Ni suppresses delta ferrite and boosts toughness | 6 – 8 | 7 |
| Moresidual only — CA6N is not Mo-alloyed (unlike CA6NM) | ≤ 0.5 | 0.2 |
| Fe | balance | — |
CA6N N+T-HT — frequently asked
What is CA6N N+T-HT used for?
CA6N N+T-HT is typically used for pump and valve bodies needing improved toughness, weld-repaired castings and corrosion-resistant structural castings. In short: highest-strength CA6 grade; tougher, weldable martensitic; mo-free CA6NM alternative.
What is the yield strength of CA6N N+T-HT?
CA6N N+T-HT has a typical yield strength of 720 MPa (104 ksi) and a tensile strength of 860 MPa (125 ksi) — stronger than 93% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is CA6N N+T-HT easy to machine?
Not especially — machinability is rated fair (40/100, better than 72% of stainless steel grades). Machine in the annealed or high-tempered state with rigid setups, sharp carbide inserts, positive rake and heavy flood coolant; work-hardens and gums up at low speed like other 12Cr martensitics.
Can CA6N N+T-HT be welded?
Yes — weldability is rated good (62/100). Weldable with matching low-C 12Cr-Ni or 410NiMo filler; preheat 100–150 °C, keep interpass below ~150 °C, and post-weld temper at 595–620 °C to restore toughness — never leave weld metal untempered.
What surface finishes work on CA6N N+T-HT?
Passivate per ASTM A967 or electropolish for corrosion service; takes a good mechanical polish, and can be hard chrome plated or nitrided below the tempering temperature.
Can CA6N N+T-HT be formed, bent or molded?
Casting alloy only: good fluidity for pumps, valve bodies and hydro turbine runners, but design generous risers and radii to avoid shrinkage porosity and hot tears; full normalize-and-temper after any weld repair.
What is the maximum service temperature of CA6N N+T-HT?
CA6N N+T-HT 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 CA6N N+T and CA6N-ANN?
N+T is the default condition — standard ASTM A743 CA6N supply condition: maximum strength with useful toughness for pump/valve pressure parts. ANN: softest condition, used between rough machining and final heat treatment or before major weld repair. Yield strength is 930 MPa in N+T versus 560 MPa in ANN.
Sources
- ASTM A743/A743M — Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application (Gr. CA6N) — ASTM International (2021)
- ASTM A781/A781M — Common Requirements for Steel and Alloy Castings — ASTM International (2020)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (cast stainless steels) — ASM International (1990)
- Steel Castings Handbook, Supplement 8 — High Alloy Data Sheets, Corrosion Series — Steel Founders' Society of America (2004)
- ASM Handbook Vol. 13B — Corrosion: Materials — ASM International (2005)
- UNS J91650 alloy record — SAE/ASTM Unified Numbering System (2019)
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.