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Stainless Steel 347 Hot Finished

Finish state

AISI/SAE 347 · UNS S34700 · ASTM A240 TP347 · EN 1.4550, X6CrNiNb18-10 · JIS SUS347

Economical large-section bar and plate for machined weldments and hot-service piping supports.

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Values for the Hot Finished condition

Other 347 tempers and conditions

347 is listed in 10 conditions; see the grade overview at 347.

Compare all 10 conditionsHide
Condition · open for datasheetBest forYield MPaTensile MPaElong. %HardnessConductivity
Annealed
softened condition (sheet/strip/wire, equivalent to solution annealed)
Soft sheet, strip and wire for forming, spinning and cold heading.24060048155 HB2.4 % IACS
Hot FinishedThis page
Hot Finished / Hot Rolled Annealed bar (ASTM A276)
Economical large-section bar and plate for machined weldments and hot-service piping supports.24060042165 HB2.4 % IACS
347H
High-carbon (0.04–0.10 % C) variant, solution annealed ≥1050 °C
Pick for ASME code creep service above 540 °C — higher allowable stresses and better rupture life than plain 347.24062045165 HB2.4 % IACS
Solution AnnealedDefault
1010–1120 °C, rapid cool (ASTM A240/A276 standard delivery)
Default stock condition for plate, sheet, bar, pipe and tube — maximum ductility and corrosion resistance.24562045160 HB—
Stabilize Annealed
870–900 °C hold after solution anneal
Extra Nb-carbide precipitation treatment for parts exposed to severe intergranular-corrosion service (nitric acid, long hot holds).25561543165 HB2.4 % IACS
As Welded
ER347 / E347 weld metal deposit
Matching filler deposit condition; used for as-welded design values in stabilized 18-8 joints.40060035180 HB2.4 % IACS
Cold Drawn
Cold Drawn / Cold Finished bar (ASTM A484, ~10–20 % reduction)
Higher strength, tighter tolerance and better surface for screw-machine parts and fasteners.5507602523 HRC2.4 % IACS
1/4 Hard
Quarter hard
Light temper rolling where extra stiffness is needed but some bending is still required.5509001225 HRC2.4 % IACS
1/2 Hard
Half hard
Springy strip for clamps, shims and gasket/bellows plies that see little forming.7901,035932 HRC2.3 % IACS
Full Hard
heavily cold rolled strip (≈ 965 MPa min yield)
Maximum strength flat product for flat springs and diaphragms; essentially no forming capability.1,0001,275638 HRC2.3 % IACS

What is 347 Hot Finished?

347 Hot Finished is 347 supplied in the Hot Finished condition — economical large-section bar and plate for machined weldments and hot-service piping supports. 347 Hot Finished has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 96% of stainless steel grades. Elongation at break is 42% and the elastic modulus is 193 GPa (28 Msi). 347 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). Solution Annealed is the default condition FabDigit quotes; Hot Finished is available on request or by drawing note.

Advantages

  • Readily welded — 90/100, better than 95% of stainless steel grades
  • Polishes to a fine finish — 80/100, better than 89% of stainless steel grades
  • Forms and bends easily — 75/100, better than 87% of stainless steel grades
  • High service temperature — 870°C (1,598 °F), better than 83% of stainless steel grades
  • Tough — resists crack growth — 195 MPa·√m (177.5 ksi·√in), better than 77% of stainless steel grades

Limitations

  • Low strength — 240 MPa (34.8 ksi), worse than 96% of stainless steel grades
  • High embodied carbon — 5.5 kg CO₂/kg, worse than 77% of stainless steel grades

347 Hot Finished properties

Typical room-temperature values for 347 Hot Finished; 22 are specific to this condition. Other listed values are 347 reference data and may not represent this condition. Bars are the position among stainless steel grades.

Physical3

347 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).

Density7.96 g/cm³0.29 lb/in³
Melting Point (Solidus)1,400°C2,552 °F
Liquidus Temperature1,425°C2,597 °F

Mechanical16

347 Hot Finished has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 96% of stainless steel grades. Elongation at break is 42% and the elastic modulus is 193 GPa (28 Msi).

Elastic (Young's) Modulus193 GPa28 Msi
Shear Modulus77 GPa11.2 Msi
Bulk Modulus160 GPa23.2 Msi
Poisson's Ratio0.29
Tensile Strength (Ultimate)600 MPa87 ksi
Yield Strength (0.2% offset)240 MPa34.8 ksi
Elongation at Break42%
Reduction in Area55%
Compressive Strength240 MPa34.8 ksi
Shear Strength410 MPa59.5 ksi
Fatigue Strength (Endurance Limit)240 MPa34.8 ksi
Fracture Toughness (K_IC)195 MPa·√m177 ksi·√in
Charpy V-Notch Impact (RT)150 J111 ft·lbf
Hardness, Brinell165 HB
Hardness, Rockwell B85 HRB
Hardness, Vickers172 HV

Thermal6

347 Hot Finished is rated for continuous service to 870°C (1,598 °F). It conducts heat at 16 W/m·K (9.24 BTU/hr·ft·°F), better than 58% of stainless steel grades. Thermal expansion is 16.6 µm/m·K (9.22 µin/in·°F).

Thermal Conductivity16 W/m·K9.2 BTU/hr·ft·°F
Specific Heat Capacity500 J/kg·K0.12 BTU/lb·°F
Thermal Expansion (CTE, 20–100 °C)16.6 µm/m·K9.2 µin/in·°F
Latent Heat of Fusion280 J/g120 BTU/lb
Max Service Temperature (continuous)870°C1,598 °F
Min Service Temperature-196°C-321 °F

Electrical3

347 Hot Finished conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.

Electrical Conductivity2.4 % IACS
Electrical Resistivity7.3×10⁻⁷ Ω·m28.7 µΩ·in
Magnetic Responsenon-magnetic (µr ≈ 1.02)

Chemical & Environmental3

Corrosion resistance is good (64/100), better than 54% of stainless steel grades.

Galvanic Potential (seawater, vs SCE)-0.08 V
Corrosion ResistanceGood64/100
Chemical Resistance SummaryGood in atmospheric, steam, hot gases, organic acids and dilute nitric; specifically resistant to intergranular attack after welding. Poor against halides — pitting and chloride SCC above ~60 °C — and against hot reducing acids (HCl, concentrated H2SO4).

Sustainability4

Producing a kilogram of 347 Hot Finished takes about 57 MJ of energy and emits 5.5 kg of CO₂ — more than 62% of stainless steel grades. Typical recycled content is 60%.

Embodied Energy (primary production)57 MJ/kg24,506 BTU/lb
Embodied Carbon (primary production)5.5 kg CO₂/kg
Embodied Water140 L/kg16.8 gal/lb
Typical Recycled Content60%

Manufacturability7

347 Hot Finished's machinability is fair (38/100, better than 63% of stainless steel grades); weldability excellent (90/100); formability very good (75/100).

MachinabilityFair38/100
Machinability Rating (AISI 1212 = 100 %)40%
WeldabilityExcellent90/100
Formability (cold)Very good75/100
Brazeability / SolderabilityVery good70/100
PolishabilityVery good80/100
Anodizing Responsen/a — stainless steel is not anodized; use electropolishing or passivation (ASTM A967) instead

Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.

Working with 347 Hot Finished

Is 347 easy to machine?

Gummy and work-hardening with abrasive NbC particles — use rigid setups, positive-rake coated carbide, heavy constant feed, no dwelling, and flood coolant; ~40 % of 1212 speeds.

Can 347 be welded?

Excellent by GTAW/GMAW/SMAW with ER347/E347 filler; the Nb stabilization means no post-weld solution anneal is needed, but keep heat input low and interpass < 150 °C to limit distortion and hot-cracking risk.

Can 347 be formed, bent or molded?

Cold forms and deep draws well but work-hardens faster than 304 — allow extra power, generous radii and intermediate anneals at 1010–1120 °C followed by rapid cooling.

What surface finishes work on 347?

Passivate per ASTM A967 or electropolish after machining; not anodizable — bead blast, No.4 brush or mirror polish are the usual finishes, and pickling paste removes weld heat tint.

347 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.

ElementSpec limit (wt %)Nominal
C347H: 0.04–0.10≤ 0.080.05
Mn≤ 21.5
Si≤ 0.750.5
P≤ 0.05—
S≤ 0.03—
Cr17 – 1918
Ni9 – 1311
NbNb(+Ta) ≥ 10×C; EN 1.4550 requires Nb ≥ 10×C, max 1.00≤ 10.6
Talimited only in nuclear/Co-controlled orders≤ 0.1—
NEN 1.4550 limit≤ 0.10.04
Febalance—

347 Hot Finished — frequently asked

What is 347 Hot Finished used for?

347 Hot Finished is typically used for boiler and superheater piping, refinery and petrochemical process piping, exhaust systems and expansion bellows, welded pressure vessels for hot service, heat exchanger tubes and tubesheets and aircraft collector rings and ducting. In short: niobium-stabilized austenitic stainless.

What is the yield strength of 347 Hot Finished?

347 Hot Finished has a typical yield strength of 240 MPa (34.8 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 96% of stainless steel grades. Strength varies by condition: see the 10 listed tempers.

Is 347 Hot Finished easy to machine?

Not especially — machinability is rated fair (38/100, better than 63% of stainless steel grades). Gummy and work-hardening with abrasive NbC particles — use rigid setups, positive-rake coated carbide, heavy constant feed, no dwelling, and flood coolant; ~40 % of 1212 speeds.

Can 347 Hot Finished be welded?

Yes — weldability is rated excellent (90/100). Excellent by GTAW/GMAW/SMAW with ER347/E347 filler; the Nb stabilization means no post-weld solution anneal is needed, but keep heat input low and interpass < 150 °C to limit distortion and hot-cracking risk.

What surface finishes work on 347 Hot Finished?

Passivate per ASTM A967 or electropolish after machining; not anodizable — bead blast, No.4 brush or mirror polish are the usual finishes, and pickling paste removes weld heat tint.

Can 347 Hot Finished be formed, bent or molded?

Cold forms and deep draws well but work-hardens faster than 304 — allow extra power, generous radii and intermediate anneals at 1010–1120 °C followed by rapid cooling.

What is the maximum service temperature of 347 Hot Finished?

347 Hot Finished 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 347 Solution Annealed and 347H?

Solution Annealed is the default condition — default stock condition for plate, sheet, bar, pipe and tube — maximum ductility and corrosion resistance. 347H: pick for ASME code creep service above 540 °C — higher allowable stresses and better rupture life than plain 347. Yield strength is 245 MPa in Solution Annealed versus 240 MPa in 347H.

Can FabDigit make parts in 347 Hot Finished?

Yes — 347 Hot Finished is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.

Sources

  1. ASTM A240/A240M — Cr and Cr-Ni Stainless Plate, Sheet and Strip — ASTM International (2023)
  2. ASTM A276/A276M — Stainless Steel Bars and Shapes — ASTM International (2023)
  3. EN 10088-2 — Stainless steels, technical delivery conditions for sheet/plate (1.4550) — CEN (2014)
  4. GB/T 1220 / GB/T 4237 (0Cr18Ni11Nb) — SAC (2015)
  5. ASM Specialty Handbook: Stainless Steels — ASM International (1994)
  6. 347/347H Stainless Steel Product Data Sheet — AK Steel / Cleveland-Cliffs (2021)
  7. Outokumpu Steel Grade 4550 datasheet — Outokumpu (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.