Stainless Steel 348H Hot Finished
Finish state
AISI/SAE 348H · UNS S34809 · ASTM A240 TP348H
Economical heavy plate and large-section bar for pressure vessel and header parts where surface finish is not critical.
Values for the Hot Finished condition
Other 348H tempers and conditions
348H is listed in 6 conditions; see the grade overview at 348H.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot FinishedThis page Hot finished / hot rolled and annealed bar and plate | Economical heavy plate and large-section bar for pressure vessel and header parts where surface finish is not critical. | 260 | 600 | 48 | 165 HB | 2.4 % IACS |
~900 °C hold after solution anneal | Choose when maximum immunity to intergranular and knife-line attack is needed after welding or for severe nitric-acid/high-temperature service. | 270 | 610 | 48 | 163 HB | 2.4 % IACS |
AnnealedDefault solution annealed (ASTM A240/A213/A479 condition A) | Standard supply condition for plate, sheet, pipe and tube used in high-temperature and nuclear pressure service. | 275 | 620 | 50 | 160 HB | — |
Cold drawn / cold finished bar and tube (lightly cold worked) | Pick for close tolerances, better surface finish and higher yield strength in small-diameter bar, tube and fasteners. | 480 | 725 | 25 | 18 HRC | 2.4 % IACS |
Quarter hard | Use for stiffer springs, clips and formed strip parts where some cold formability must remain. | 515 | 860 | 12 | 25 HRC | 2.4 % IACS |
Half hard | Highest strength normally stocked in strip form; only mild bending is possible. | 760 | 1,035 | 8 | 32 HRC | 2.4 % IACS |
What is 348H Hot Finished?
348H Hot Finished is 348H supplied in the Hot Finished condition — economical heavy plate and large-section bar for pressure vessel and header parts where surface finish is not critical. 348H Hot Finished 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 48% and the elastic modulus is 195 GPa (28.3 Msi). 348H Hot Finished has a density of 7.96 g/cm³ (0.288 lb/in³), heavier than 83% of stainless steel grades. It melts at 1,400°C (2,552 °F). Annealed is the default condition FabDigit quotes; Hot Finished is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 48%, better than 85% of stainless steel grades
- Readily welded — 80/100, better than 80% of stainless steel grades
- Tough — resists crack growth — 190 MPa·√m (172.9 ksi·√in), better than 77% of stainless steel grades
- High service temperature — 815°C (1,499 °F), better than 77% of stainless steel grades
Limitations
- Low strength — 260 MPa (37.7 ksi), worse than 84% of stainless steel grades
- Needs corrosion protection — 52/100, worse than 76% of stainless steel grades
348H Hot Finished properties
Typical room-temperature values for 348H Hot Finished; 22 are specific to this condition. Other listed values are 348H reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
348H Hot Finished has a density of 7.96 g/cm³ (0.288 lb/in³), heavier than 83% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
348H Hot Finished 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 48% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
348H Hot Finished is rated for continuous service to 815°C (1,499 °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
348H Hot Finished conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (52/100), worse than 76% of stainless steel grades.
Sustainability4
Producing a kilogram of 348H Hot Finished takes about 78 MJ of energy and emits 5 kg of CO₂ — more than 87% of stainless steel grades. Typical recycled content is 55%.
Manufacturability7
348H Hot Finished's machinability is fair (36/100, better than 57% of stainless steel grades); weldability very good (80/100); formability good (65/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 348H Hot Finished
Is 348H easy to machine?
Gummy and work-hardening with abrasive Nb/Ta carbides — use rigid setups, sharp positive-rake carbide, ~30–60 m/min, heavy positive feed and flood coolant; avoid dwelling to prevent glazing.
Can 348H be welded?
Readily welded by GTAW/GMAW/SMAW with ER347/E347 filler; no post-weld anneal is normally required, but minimise heat input and consider a ~900 °C stabilising anneal where knife-line attack or hot nitric service is a concern.
Can 348H be formed, bent or molded?
Cold forms well in the annealed condition though springback and work hardening exceed 304; hot work at 1150–1200 °C and always solution anneal at 1040–1100 °C followed by rapid cooling.
What surface finishes work on 348H?
Cannot be anodised — pickle and passivate per ASTM A380/A967, electropolish for nuclear cleanliness; takes a good mechanical polish, with carbide stringers occasionally showing as faint comet tails.
348H 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 carbon for creep strength (the 'H' grade) | 0.04 – 0.1 | 0.07 |
| Cr | 17 – 19 | 18 |
| Ni | 9 – 13 | 11 |
| NbNb (+Ta) ≥ 8 × C; Nb+Ta reported together | 0.56 – 1 | 0.75 |
| Tarestricted for nuclear (low neutron capture) | ≤ 0.1 | 0.05 |
| Corestricted for nuclear service | ≤ 0.2 | 0.1 |
| 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 |
| Fe | balance | — |
348H Hot Finished — frequently asked
What is 348H Hot Finished used for?
348H Hot Finished is typically used for nuclear reactor piping, high-temperature nuclear components, reactor internal support structures, superheater and reheater tubing, high-temperature steam headers and spools and forged valve and fitting bodies for hot service. In short: creep-resistant 348 variant; nuclear-service stabilised grade; 815 °C service limit.
What is the yield strength of 348H Hot Finished?
348H Hot Finished 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 6 listed tempers.
Is 348H Hot Finished easy to machine?
Not especially — machinability is rated fair (36/100, better than 57% of stainless steel grades). Gummy and work-hardening with abrasive Nb/Ta carbides — use rigid setups, sharp positive-rake carbide, ~30–60 m/min, heavy positive feed and flood coolant; avoid dwelling to prevent glazing.
Can 348H Hot Finished be welded?
Yes — weldability is rated very good (80/100). Readily welded by GTAW/GMAW/SMAW with ER347/E347 filler; no post-weld anneal is normally required, but minimise heat input and consider a ~900 °C stabilising anneal where knife-line attack or hot nitric service is a concern.
What surface finishes work on 348H Hot Finished?
Cannot be anodised — pickle and passivate per ASTM A380/A967, electropolish for nuclear cleanliness; takes a good mechanical polish, with carbide stringers occasionally showing as faint comet tails.
Can 348H Hot Finished be formed, bent or molded?
Cold forms well in the annealed condition though springback and work hardening exceed 304; hot work at 1150–1200 °C and always solution anneal at 1040–1100 °C followed by rapid cooling.
What is the maximum service temperature of 348H Hot Finished?
348H Hot Finished is rated for continuous use to about 815°C (1,499 °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 (TP348H, S34809) — ASTM International (2023)
- ASTM A213/A213M — Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater and Heat-Exchanger Tubes — ASTM International (2022)
- ASTM A479/A479M — Stainless Steel Bars and Shapes for Boilers and Other Pressure Vessels — ASTM International (2021)
- ASME BPVC Section II Part D — Properties (Metric), austenitic stainless allowable stresses — ASME (2023)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ATI 347 / ATI 348 Technical Data Sheet — ATI Specialty Materials (2020)
- Machinery's Handbook — machinability ratings for stainless steels — Industrial Press (2020)
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.