Stainless Steel 347LN Annealed
Temper · default condition
AISI/SAE 347LN · UNS S34751
Standard supply condition for plate, pipe, tube, bar and forgings; maximum corrosion resistance and ductility for nuclear/pressure service.
Values for the Annealed condition
Other 347LN tempers and conditions
347LN is listed in 8 conditions; see the grade overview at 347LN.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefaultThis page solution annealed 1040–1120 °C, rapid quenched | Standard supply condition for plate, pipe, tube, bar and forgings; maximum corrosion resistance and ductility for nuclear/pressure service. | 290 | 620 | 50 | 160 HB | — |
880–930 °C hold after solution anneal | Chosen for severe hot nitric-acid or long high-temperature service where all residual carbon must be tied up as NbC. | 300 | 610 | 45 | 165 HB | 2.4 % IACS |
As-welded deposit (ER347 / E347 type filler, no PWHT) | Design basis for weld metal and HAZ in nuclear/piping joints welded without post-weld solution anneal. | 400 | 600 | 35 | 180 HB | 2.3 % IACS |
Cold drawn / cold finished bar (annealed + drawn) | Bar and tube where tighter tolerance, better surface and higher yield strength are needed than annealed. | 500 | 720 | 30 | 16 HRC | 2.4 % IACS |
Quarter hard | Light cold-rolled temper for springy sheet parts still needing appreciable forming ability. | 545 | 880 | 12 | 25 HRC | 2.4 % IACS |
Half hard | Structural sheet, clamps and springs where strength outweighs formability. | 790 | 1,060 | 10 | 32 HRC | 2.4 % IACS |
Three-quarter hard | High-strength strip for flat springs and shims with only simple bends. | 960 | 1,230 | 7 | 37 HRC | 2.4 % IACS |
heavily cold rolled strip per ASTM A666 | Maximum strength thin strip; essentially no forming beyond flat blanking. | 1,000 | 1,300 | 4 | 40 HRC | 2.4 % IACS |
What is 347LN Annealed?
347LN Annealed is 347LN in the Annealed temper — standard supply condition for plate, pipe, tube, bar and forgings; maximum corrosion resistance and ductility for nuclear/pressure service. 347LN Annealed has a yield strength of 290 MPa (42.1 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 72% of stainless steel grades. Elongation at break is 50% and the elastic modulus is 195 GPa (28.3 Msi). 347LN Annealed 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 — 88/100, better than 91% of stainless steel grades
- Ductile — tolerates forming and impact — 50%, better than 90% of stainless steel grades
- Forms and bends easily — 78/100, better than 90% of stainless steel grades
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 86% of stainless steel grades
347LN Annealed properties
Typical room-temperature values for 347LN Annealed; 16 are specific to this condition. Other listed values are 347LN reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
347LN Annealed 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
347LN Annealed has a yield strength of 290 MPa (42.1 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 72% of stainless steel grades. Elongation at break is 50% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
347LN Annealed is rated for continuous service to 800°C (1,472 °F). It conducts heat at 16.2 W/m·K (9.36 BTU/hr·ft·°F), better than 64% of stainless steel grades. Thermal expansion is 16.5 µm/m·K (9.17 µin/in·°F).
Electrical3
347LN Annealed conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 63% of stainless steel grades.
Sustainability4
Producing a kilogram of 347LN Annealed takes about 53 MJ of energy and emits 5.2 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 60%.
Manufacturability8
347LN Annealed's machinability is fair (38/100, better than 63% of stainless steel grades); weldability excellent (88/100); formability very good (78/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 347LN Annealed
Is 347LN easy to machine?
Cut like 347/321 — rigid setups, sharp positive-rake carbide, heavy flood coolant, 20–30 % lower speed than 304 because NbC particles are abrasive and chips are stringy.
Can 347LN be welded?
Excellent: GTAW/GMAW/SMAW with ER347/E347 (or Nb-free 316L only where allowed); low heat input, interpass ≤150 °C, no post-weld anneal needed thanks to ultra-low C plus Nb.
Can 347LN be formed, bent or molded?
Very ductile hot (1150–1250 °C) and cold, but work-hardens fast — allow for springback, use interstage anneals for deep draws and avoid stopping hot work below ~900 °C.
What surface finishes work on 347LN?
Pickle (HNO₃/HF) or electropolish after fabrication and passivate per ASTM A967; polishes to a mirror finish; never anodised, and avoid iron contamination from carbon-steel tooling.
347LN 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 |
|---|---|---|
| Cultra-low carbon, controlled range | 0.01 – 0.02 | 0.01 |
| Nnitrogen-strengthened | 0.06 – 0.1 | 0.08 |
| Cr | 17 – 19 | 18 |
| Ni | 9 – 13 | 10.5 |
| Nbstabiliser; standard requires ≥15×C (Nb+Ta basis in some specs) | 0.2 – 1 | 0.4 |
| Mn | ≤ 2 | 1.5 |
| Si | ≤ 1 | 0.5 |
| P | ≤ 0.05 | — |
| Snuclear orders often restrict S ≤0.015 and Co ≤0.05 | ≤ 0.03 | — |
| Fe | balance | — |
347LN Annealed — frequently asked
What is 347LN Annealed used for?
347LN Annealed is typically used for nuclear primary and secondary piping, high-pressure welded piping systems, superheater and reheater tubing, pressure vessel shells and nozzles, steam headers and manifolds and welded expansion joints and bellows. In short: stabilized, sensitization-resistant 347; nitrogen-boosted weld strength; nuclear-grade piping choice.
What is the yield strength of 347LN Annealed?
347LN Annealed has a typical yield strength of 290 MPa (42.1 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 72% of stainless steel grades. Strength varies by condition: see the 8 listed tempers.
Is 347LN Annealed easy to machine?
Not especially — machinability is rated fair (38/100, better than 63% of stainless steel grades). Cut like 347/321 — rigid setups, sharp positive-rake carbide, heavy flood coolant, 20–30 % lower speed than 304 because NbC particles are abrasive and chips are stringy.
Can 347LN Annealed be welded?
Yes — weldability is rated excellent (88/100). Excellent: GTAW/GMAW/SMAW with ER347/E347 (or Nb-free 316L only where allowed); low heat input, interpass ≤150 °C, no post-weld anneal needed thanks to ultra-low C plus Nb.
What surface finishes work on 347LN Annealed?
Pickle (HNO₃/HF) or electropolish after fabrication and passivate per ASTM A967; polishes to a mirror finish; never anodised, and avoid iron contamination from carbon-steel tooling.
Can 347LN Annealed be formed, bent or molded?
Very ductile hot (1150–1250 °C) and cold, but work-hardens fast — allow for springback, use interstage anneals for deep draws and avoid stopping hot work below ~900 °C.
What is the maximum service temperature of 347LN Annealed?
347LN Annealed 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.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet and Strip (UNS S34751) — ASTM International (2023)
- ASTM A312/A312M — Seamless and Welded Austenitic Stainless Steel Pipes — ASTM International (2022)
- ASTM A666 — Annealed or Cold-Worked Austenitic Stainless Steel Sheet, Strip, Plate and Flat Bar — ASTM International (2015)
- ASME BPVC Section II Part D — Material Properties (physical/allowable stress tables for 347 group) — ASME (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- EN 10088-2 / 1.4550 (X6CrNiNb18-10) stabilised austenitic stainless — CEN (2014)
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.