Stainless Steel 348 · heat-treated state
Stainless Steel 348-SA
Properties of the SA condition, compared with the other 348 tempers.
Choose for heavy welded nuclear assemblies or service in the 425–815 °C sensitizing range to tie up carbon as NbC and prevent knife-line attack.
What is 348-SA?
348-SA is 348 heat treated to SA — choose for heavy welded nuclear assemblies or service in the 425–815 °C sensitizing range to tie up carbon as NbC and prevent knife-line attack. 348-SA has a yield strength of 255 MPa (37 ksi) and a tensile strength of 615 MPa (89.2 ksi) — weaker than 87% of stainless steel grades. Elongation at break is 43% and the elastic modulus is 193 GPa (28 Msi). 348-SA has a density of 7.96 g/cm³ (0.288 lb/in³), heavier than 82% of stainless steel grades. It melts at 1,400°C (2,552 °F). Annealed is the default condition FabDigit quotes; SA is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 220 MPa·√m (200.2 ksi·√in), better than 97% of stainless steel grades
- Forms and bends easily — 80/100, better than 93% of stainless steel grades
- Readily welded — 85/100, better than 86% of stainless steel grades
- High service temperature — 870°C (1,598 °F), better than 82% of stainless steel grades
Limitations
- Low strength — 255 MPa (37 ksi), worse than 87% of stainless steel grades
348-SA properties
Typical room-temperature values for 348-SA — 6 properties are specific to this condition; the rest are grade-level values shared by every 348 temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.
Physical3
348-SA has a density of 7.96 g/cm³ (0.288 lb/in³), heavier than 82% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
348-SA has a yield strength of 255 MPa (37 ksi) and a tensile strength of 615 MPa (89.2 ksi) — weaker than 87% of stainless steel grades. Elongation at break is 43% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
348-SA is rated for continuous service to 870°C (1,598 °F). It conducts heat at 16.3 W/m·K (9.42 BTU/hr·ft·°F), better than 68% of stainless steel grades. Thermal expansion is 16.6 µm/m·K (9.22 µin/in·°F).
Electrical3
348-SA conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (66/100), better than 58% of stainless steel grades.
Sustainability4
Producing a kilogram of 348-SA takes about 53 MJ of energy and emits 5.4 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 55%.
Manufacturability8
348-SA's machinability is fair (38/100, better than 63% of stainless steel grades); weldability excellent (85/100); formability very good (80/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 348 tempers and conditions
348 is also supplied in 8 other conditions. The full side-by-side table is on the 348 overview.
- AnnealedDefaultStandard stocked condition for plate, pipe, tube and forgings; maximum ductility and corrosion resistance.250 MPa yield · 160 HB
- CDPick for straight, close-tolerance bar and fasteners needing higher yield strength and better machined finish than annealed.480 MPa yield · 210 HB
- SAChoose for heavy welded nuclear assemblies or service in the 425–815 °C sensitizing range to tie up carbon as NbC and prevent knife-line attack.255 MPa yield · 165 HB
Working with 348-SA
Is 348 easy to machine?
Work-hardens rapidly and NbC particles are abrasive — use rigid setups, positive-rake carbide, heavy constant feed, no dwelling, and flood coolant.
Can 348 be welded?
Readily welded by GTAW/GMAW/SMAW with ER/E347-type filler (order low-Ta, low-Co filler for nuclear work); no post-weld anneal normally needed, but stabilize-anneal heavy sections and avoid excessive heat input to limit hot cracking.
Can 348 be formed, bent or molded?
Excellent cold formability with high work-hardening rate; allow ~50 % more press force and more springback than carbon steel, and interstage anneal for severe draws.
What surface finishes work on 348?
Passivate per ASTM A967 or electropolish after fabrication; pickle/blast weld scale off to restore the passive film — not anodizable.
348 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 |
|---|---|---|
| C0.04–0.10 for 348H | ≤ 0.08 | 0.05 |
| Mn | ≤ 2 | 1.5 |
| Si1.00 max in some product specs | ≤ 0.75 | 0.5 |
| P | ≤ 0.05 | 0.03 |
| S | ≤ 0.03 | 0.01 |
| Cr | 17 – 19 | 18 |
| Ni | 9 – 13 | 11 |
| NbNb+Ta ≥ 10×C (≥ 8×C for 348H), 1.10 max total | ≤ 1.1 | 0.7 |
| Tarestricted for low neutron activation | ≤ 0.1 | 0.05 |
| Corestricted to limit Co-60 activation | ≤ 0.2 | 0.1 |
| Fe | balance | — |
348-SA — frequently asked
What is 348-SA used for?
348-SA is typically used for nuclear reactor internals, radiation-service piping and fittings, reactor vessel cladding and liners, steam and superheater tubing (348H), instrumentation tubing in reactor systems and pressure vessel shells and nozzles. In short: low-Ta, low-Co 347; nuclear reactor grade; stabilized for 870 °C service.
What is the yield strength of 348-SA?
348-SA has a typical yield strength of 255 MPa (37 ksi) and a tensile strength of 615 MPa (89.2 ksi) — weaker than 87% of stainless steel grades. Strength varies by condition: see the 9 listed tempers.
Is 348-SA easy to machine?
Not especially — machinability is rated fair (38/100, better than 63% of stainless steel grades). Work-hardens rapidly and NbC particles are abrasive — use rigid setups, positive-rake carbide, heavy constant feed, no dwelling, and flood coolant.
Can 348-SA be welded?
Yes — weldability is rated excellent (85/100). Readily welded by GTAW/GMAW/SMAW with ER/E347-type filler (order low-Ta, low-Co filler for nuclear work); no post-weld anneal normally needed, but stabilize-anneal heavy sections and avoid excessive heat input to limit hot cracking.
What surface finishes work on 348-SA?
Passivate per ASTM A967 or electropolish after fabrication; pickle/blast weld scale off to restore the passive film — not anodizable.
Can 348-SA be formed, bent or molded?
Excellent cold formability with high work-hardening rate; allow ~50 % more press force and more springback than carbon steel, and interstage anneal for severe draws.
What is the maximum service temperature of 348-SA?
348-SA is rated for continuous use to about 870°C (1,598 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 348 Annealed and 348-FH?
Annealed is the default condition — standard stocked condition for plate, pipe, tube and forgings; maximum ductility and corrosion resistance. FH: maximum cold-worked strength strip/wire; essentially flat-only parts, blanking and springs. Yield strength is 250 MPa in Annealed versus 1,000 MPa in FH.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet and Strip — ASTM International (2023)
- ASTM A312/A312M — Seamless and Welded Austenitic Stainless Steel Pipe — ASTM International (2022)
- ASTM A479/A479M — Stainless Steel Bars and Shapes for Pressure Vessels — ASTM International (2023)
- SAE AMS 5512 / UNS S34800 designation data — SAE International (2019)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASME BPVC Section II Part D — allowable stresses for TP348/TP348H — ASME (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.