Stainless Steel 1.4912-AT (Solution Annealed)
Precip hard · default condition
EN 1.4912 · UNS S34700 · AISI/SAE 347 · JIS SUS347 · GB 06Cr18Ni11Nb
Standard supply condition for plate, tube and pipe — maximum ductility and corrosion resistance, the basis of all code allowable stresses.
Values for the AT condition
Other 1.4912 tempers and conditions
1.4912 is listed in 9 conditions; see the grade overview at 1.4912.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Forged + Solution Annealed (bar, forgings, flanges) | For valve bodies, flanges and heavy fittings to ASTM A182 F347/F347H; solution treatment after forging restores corrosion resistance. | 250 | 570 | 42 | 165 HB | 2.4 % IACS |
Hardened | Ordered when ASME code creep allowables above 540 °C are needed: C ≥ 0.04 % and grain size ≥ ASTM 7 or coarser after high-temperature solution treatment. | 255 | 600 | 42 | 165 HB | 2.4 % IACS |
ATDefaultThis page Solution Annealed | Standard supply condition for plate, tube and pipe — maximum ductility and corrosion resistance, the basis of all code allowable stresses. | 260 | 600 | 45 | 160 HB | — |
Solution Annealed + Stabilizing Anneal | Choose when the part will see severe or long-term service in the sensitization range or in hot nitric/polythionic acid service — forces all carbon into NbC before service. | 265 | 590 | 42 | 165 HB | 2.4 % IACS |
Cold drawn | Bar and tube with tight tolerances and ~50 % higher yield strength; use where extra strength and straightness beat maximum ductility. | 450 | 700 | 30 | 220 HB | — |
Quarter hard | Light cold-rolled temper for springy panels and mildly formed parts needing higher yield than annealed. | 550 | 900 | 12 | 27 HRC | 2.4 % IACS |
Half hard | Medium temper for flat springs, clamps and structural strip with only simple bends. | 800 | 1,070 | 9 | 32 HRC | 2.4 % IACS |
Three-quarter hard | High-strength strip where forming is limited to shallow bends across the rolling direction. | 960 | 1,240 | 6 | 37 HRC | 2.4 % IACS |
Full hard | Maximum cold-worked strength for flat springs and shims; essentially non-formable and must not be welded without re-annealing. | 1,000 | 1,300 | 5 | 40 HRC | 2.4 % IACS |
What is 1.4912-AT?
1.4912-AT is 1.4912 in the AT condition — standard supply condition for plate, tube and pipe — maximum ductility and corrosion resistance, the basis of all code allowable stresses. 1.4912-AT has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 84% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 200 GPa (29 Msi). 1.4912-AT has a density of 7.95 g/cm³ (0.287 lb/in³), heavier than 81% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Advantages
- Readily welded — 90/100, better than 95% of stainless steel grades
- Forms and bends easily — 80/100, better than 93% of stainless steel grades
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 86% of stainless steel grades
- Ductile — tolerates forming and impact — 45%, better than 76% of stainless steel grades
Limitations
- Low strength — 260 MPa (37.7 ksi), worse than 84% of stainless steel grades
1.4912-AT properties
Typical room-temperature values for 1.4912-AT; 16 are specific to this condition. Other listed values are 1.4912 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
1.4912-AT has a density of 7.95 g/cm³ (0.287 lb/in³), heavier than 81% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
1.4912-AT has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 84% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
1.4912-AT is rated for continuous service to 800°C (1,472 °F). It conducts heat at 15.5 W/m·K (8.96 BTU/hr·ft·°F), better than 53% of stainless steel grades. Thermal expansion is 16.5 µm/m·K (9.17 µin/in·°F).
Electrical3
1.4912-AT conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (66/100), better than 59% of stainless steel grades.
Sustainability4
Producing a kilogram of 1.4912-AT takes about 55 MJ of energy and emits 5.2 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 60%.
Manufacturability6
1.4912-AT's machinability is fair (40/100, better than 72% of stainless steel grades); weldability excellent (90/100); formability very good (80/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1.4912-AT
Is 1.4912 easy to machine?
Gummy and strongly work-hardening — use rigid setups, sharp positive-rake carbide, heavy positive feed (never dwell), 60–120 m/min turning, and flood emulsion or high-pressure coolant.
Can 1.4912 be welded?
Excellent by GTAW/GMAW/SMAW with matched ER347/E347 filler; Nb stabilization removes the need for post-weld solution anneal, but keep interpass temperature low and avoid excessive dilution to limit hot-cracking (aim for 3–8 FN in the deposit).
Can 1.4912 be formed, bent or molded?
Deep drawable when annealed (high n-value) but springback and force are ~50 % higher than carbon steel; allow generous bend radii, interstage anneal for severe draws, and expect slight magnetism only after very heavy cold work.
What surface finishes work on 1.4912?
Pickle and passivate (HNO3 or citric) after welding or hot work to restore the passive film; takes No.4, BA and mirror polishes readily; not anodizable — electropolishing is the preferred high-purity finish.
1.4912 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 |
|---|---|---|
| Craised vs 1.4550 for creep strength | 0.04 – 0.1 | 0.07 |
| Si | ≤ 1 | 0.5 |
| Mn | ≤ 2 | 1.5 |
| P | ≤ 0.04 | 0.03 |
| S | ≤ 0.02 | 0.01 |
| Cr | 17 – 19 | 18 |
| Ni | 9 – 12 | 10.5 |
| NbNb ≥ 10×C (ASTM 347 allows Nb ≥ 10×C, max 1.00; Nb+Ta basis) | 0.7 – 1.2 | 0.85 |
| Fe | balance | — |
1.4912-AT — frequently asked
What is 1.4912-AT used for?
1.4912-AT is typically used for welded chemical process piping, power plant components, aircraft exhaust collector rings and pressure vessels. In short: nb-stabilised weldable 18-10; no post-weld anneal needed; higher hot strength than 304.
What is the yield strength of 1.4912-AT?
1.4912-AT has a typical yield strength of 260 MPa (37.7 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 84% of stainless steel grades. Strength varies by condition: see the 9 listed tempers.
Is 1.4912-AT easy to machine?
Not especially — machinability is rated fair (40/100, better than 72% of stainless steel grades). Gummy and strongly work-hardening — use rigid setups, sharp positive-rake carbide, heavy positive feed (never dwell), 60–120 m/min turning, and flood emulsion or high-pressure coolant.
Can 1.4912-AT be welded?
Yes — weldability is rated excellent (90/100). Excellent by GTAW/GMAW/SMAW with matched ER347/E347 filler; Nb stabilization removes the need for post-weld solution anneal, but keep interpass temperature low and avoid excessive dilution to limit hot-cracking (aim for 3–8 FN in the deposit).
What surface finishes work on 1.4912-AT?
Pickle and passivate (HNO3 or citric) after welding or hot work to restore the passive film; takes No.4, BA and mirror polishes readily; not anodizable — electropolishing is the preferred high-purity finish.
Can 1.4912-AT be formed, bent or molded?
Deep drawable when annealed (high n-value) but springback and force are ~50 % higher than carbon steel; allow generous bend radii, interstage anneal for severe draws, and expect slight magnetism only after very heavy cold work.
What is the maximum service temperature of 1.4912-AT?
1.4912-AT is rated for continuous use to about 800°C (1,472 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1.4912-AT and 1.4912-FH?
AT is the default condition — standard supply condition for plate, tube and pipe — maximum ductility and corrosion resistance, the basis of all code allowable stresses. FH: maximum cold-worked strength for flat springs and shims; essentially non-formable and must not be welded without re-annealing. Yield strength is 260 MPa in AT versus 1,000 MPa in FH.
Sources
- EN 10088-1/-2/-3 Stainless steels — list of grades and technical delivery conditions — CEN (2014)
- EN 10216-5 Seamless steel tubes for pressure purposes — stainless steel tubes — CEN (2021)
- EN 10302 Creep resisting steels, nickel and cobalt alloys — CEN (2008)
- ASTM A240/A213/A312/A182 (Type 347 / 347H, UNS S34700/S34709) — ASTM International (2023)
- GB/T 24511 / GB/T 20878 06Cr18Ni11Nb — SAC (2017)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.13B — Corrosion: Materials — ASM International (2005)
- Sandvik/Alleima 3R66 & Outokumpu 4550/4912 stainless datasheets — Alleima / Outokumpu (2023)
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.