Stainless Steel 1.3956-AT (Solution annealed)
Precip hard · default condition
EN 1.3956
Standard delivery condition: maximum toughness, lowest permeability and best corrosion resistance — use for all cryogenic and non-magnetic service.
Values for the AT condition
Other 1.3956 tempers and conditions
1.3956 is listed in 3 conditions; see the grade overview at 1.3956.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ATDefaultThis page Solution annealed | Standard delivery condition: maximum toughness, lowest permeability and best corrosion resistance — use for all cryogenic and non-magnetic service. | 340 | 660 | 35 | 195 HB | — |
Hot isostatically pressed then solution annealed | Pick for pressure-retaining or fatigue-loaded cryogenic castings where microporosity must be eliminated (radiographic Level 1). | 350 | 690 | 42 | 195 HB | 2 % IACS |
As fabricated | Rough/unfinished condition only — interdendritic carbo-nitrides raise hardness but cut toughness, corrosion resistance and magnetic purity; not for cryogenic or corrosive duty. | 360 | 620 | 18 | 17 HRC | 2 % IACS |
What is 1.3956-AT?
1.3956-AT is 1.3956 in the AT condition — standard delivery condition: maximum toughness, lowest permeability and best corrosion resistance — use for all cryogenic and non-magnetic service. 1.3956-AT has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 55% of stainless steel grades. Elongation at break is 35% and the elastic modulus is 196 GPa (28.4 Msi). 1.3956-AT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 59% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Advantages
- Tough — resists crack growth — 190 MPa·√m (172.9 ksi·√in), better than 77% of stainless steel grades
Limitations
- Limited formability — 20/100, worse than 86% of stainless steel grades
- Hard to polish — 60/100, worse than 80% of stainless steel grades
- Low electrical conductivity — 2 % IACS, worse than 77% of stainless steel grades
1.3956-AT properties
Typical room-temperature values for 1.3956-AT; 11 are specific to this condition. Other listed values are 1.3956 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.3956-AT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 59% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
1.3956-AT has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 55% of stainless steel grades. Elongation at break is 35% and the elastic modulus is 196 GPa (28.4 Msi).
Thermal6
1.3956-AT is rated for continuous service to 550°C (1,022 °F). It conducts heat at 14 W/m·K (8.09 BTU/hr·ft·°F), worse than 80% of stainless steel grades. Thermal expansion is 16.5 µm/m·K (9.17 µin/in·°F).
Electrical3
1.3956-AT conducts electricity at 2 % IACS, worse than 77% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 63% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.3956-AT takes about 55 MJ of energy and emits 4.5 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 65%.
Manufacturability7
1.3956-AT's machinability is poor (28/100, worse than 79% of stainless steel grades); weldability very good (70/100); formability poor (20/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.3956-AT
Is 1.3956 easy to machine?
Treat like Nitronic 50: rigid setups, sharp positive-rake carbide/ceramic, heavy constant feed and flood coolant — light cuts glaze and work-harden the surface; expect ~30 % of 1212 rates.
Can 1.3956 be welded?
Readily welded by GTAW/GMAW/SMAW with matching 22-12-5 high-N or 209/240-type filler, no preheat, interpass <150 °C; re-solution anneal heavy repairs to restore toughness and low permeability.
Can 1.3956 be formed, bent or molded?
Foundry grade — use generous risering for the long freezing range, avoid N loss in the melt, and always solution anneal + water quench before machining or service.
What surface finishes work on 1.3956?
Pickle and passivate after heat treatment to remove the Cr/N-rich scale; grinds and polishes well but casting porosity limits mirror finishes; do not use ferritic grinding media on non-magnetic parts.
1.3956 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 |
|---|---|---|
| CGX4 = ~0.04 % C nominal | ≤ 0.06 | 0.04 |
| Si | ≤ 1 | 0.6 |
| Mnraises N solubility, stabilises austenite | 4 – 6 | 5 |
| P | ≤ 0.04 | — |
| S | ≤ 0.03 | — |
| Cr | 21 – 23 | 22 |
| Ni | 11 – 13 | 12 |
| Moresidual unless specially ordered | ≤ 0.5 | — |
| Nprincipal solid-solution strengthener | 0.15 – 0.3 | 0.22 |
| Fe | balance | — |
1.3956-AT — frequently asked
What is 1.3956-AT used for?
1.3956-AT is typically used for cryogenic valve bodies, non-magnetic fittings and low-temperature process castings. In short: non-magnetic cast austenitic; cryogenic toughness; nitrogen-strengthened, 340 MPa yield.
What is the yield strength of 1.3956-AT?
1.3956-AT has a typical yield strength of 340 MPa (49.3 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 55% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is 1.3956-AT easy to machine?
Not especially — machinability is rated poor (28/100, worse than 79% of stainless steel grades). Treat like Nitronic 50: rigid setups, sharp positive-rake carbide/ceramic, heavy constant feed and flood coolant — light cuts glaze and work-harden the surface; expect ~30 % of 1212 rates.
Can 1.3956-AT be welded?
Yes — weldability is rated very good (70/100). Readily welded by GTAW/GMAW/SMAW with matching 22-12-5 high-N or 209/240-type filler, no preheat, interpass <150 °C; re-solution anneal heavy repairs to restore toughness and low permeability.
What surface finishes work on 1.3956-AT?
Pickle and passivate after heat treatment to remove the Cr/N-rich scale; grinds and polishes well but casting porosity limits mirror finishes; do not use ferritic grinding media on non-magnetic parts.
Can 1.3956-AT be formed, bent or molded?
Foundry grade — use generous risering for the long freezing range, avoid N loss in the melt, and always solution anneal + water quench before machining or service.
What is the maximum service temperature of 1.3956-AT?
1.3956-AT is rated for continuous use to about 550°C (1,022 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1.3956-AT and 1.3956-F?
AT is the default condition — standard delivery condition: maximum toughness, lowest permeability and best corrosion resistance — use for all cryogenic and non-magnetic service. F: rough/unfinished condition only — interdendritic carbo-nitrides raise hardness but cut toughness, corrosion resistance and magnetic purity; not for cryogenic or corrosive duty. Yield strength is 340 MPa in AT versus 360 MPa in F.
Sources
- EN 10213 — Steel castings for pressure purposes — CEN (2016)
- SEW 410 / DIN 17445 — Stainless and non-magnetic steel castings — VDEh / DIN (1998)
- ASTM A743/A743M (CG6MMN, comparable cast 22-12-5 N grade) — ASTM (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- Non-magnetic austenitic stainless steel castings (22Cr-12Ni-5Mn-N) data — Steel foundry datasheets (2022)
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.