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Stainless Steel 347 Full Hard

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

Maximum strength flat product for flat springs and diaphragms; essentially no forming capability.

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Values for the Full Hard 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 Finished
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 HardThis page
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 Full Hard?

347 Full Hard is 347 supplied in the Full Hard condition — maximum strength flat product for flat springs and diaphragms; essentially no forming capability. 347 Full Hard has a yield strength of 1,000 MPa (145 ksi) and a tensile strength of 1,275 MPa (185 ksi) — stronger than 98% of stainless steel grades. Elongation at break is 6% and the elastic modulus is 193 GPa (28 Msi). 347 Full Hard 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; Full Hard is available on request or by drawing note.

Advantages

  • High strength — 1,000 MPa (145 ksi), better than 98% of stainless steel grades
  • Polishes to a fine finish — 80/100, better than 89% of stainless steel grades

Limitations

  • Limited ductility — 6%, worse than 99% of stainless steel grades
  • Limited formability — 20/100, worse than 86% of stainless steel grades
  • Limited service temperature — 315°C (599 °F), worse than 85% of stainless steel grades
  • Low fracture toughness — 80 MPa·√m (72.8 ksi·√in), worse than 79% of stainless steel grades
  • High embodied carbon — 5.5 kg CO₂/kg, worse than 77% of stainless steel grades

347 Full Hard properties

Typical room-temperature values for 347 Full Hard; 23 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 Full Hard 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 Full Hard has a yield strength of 1,000 MPa (145 ksi) and a tensile strength of 1,275 MPa (185 ksi) — stronger than 98% of stainless steel grades. Elongation at break is 6% 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)1,275 MPa185 ksi
Yield Strength (0.2% offset)1,000 MPa145 ksi
Elongation at Break6%
Reduction in Area20%
Compressive Strength1,000 MPa145 ksi
Shear Strength750 MPa109 ksi
Fatigue Strength (Endurance Limit)480 MPa69.6 ksi
Fracture Toughness (K_IC)80 MPa·√m72.8 ksi·√in
Charpy V-Notch Impact (RT)30 J22.1 ft·lbf
Hardness, Brinell370 HB
Hardness, Rockwell B82 HRB
Hardness, Vickers385 HV

Thermal6

347 Full Hard is rated for continuous service to 315°C (599 °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)315°C599 °F
Min Service Temperature-196°C-321 °F

Electrical3

347 Full Hard conducts electricity at 2.3 % IACS, better than 55% of stainless steel grades.

Electrical Conductivity2.3 % IACS
Electrical Resistivity7.5×10⁻⁷ Ω·m29.5 µΩ·in
Magnetic Responsemoderately magnetic from deformation martensite

Chemical & Environmental3

Corrosion resistance is good (62/100), worse than 52% of stainless steel grades.

Galvanic Potential (seawater, vs SCE)-0.08 V
Corrosion ResistanceGood62/100
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 Full Hard 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 Full Hard's machinability is poor (30/100, worse than 70% of stainless steel grades); weldability very good (70/100); formability poor (20/100).

MachinabilityPoor30/100
Machinability Rating (AISI 1212 = 100 %)30%
WeldabilityVery good70/100
Formability (cold)Poor20/100
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 Full Hard

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 Full Hard — frequently asked

What is 347 Full Hard used for?

347 Full Hard 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 Full Hard?

347 Full Hard has a typical yield strength of 1,000 MPa (145 ksi) and a tensile strength of 1,275 MPa (185 ksi) — stronger than 98% of stainless steel grades. Strength varies by condition: see the 10 listed tempers.

Is 347 Full Hard easy to machine?

Not especially — machinability is rated poor (30/100, worse than 70% 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 Full Hard be welded?

Yes — weldability is rated very good (70/100). 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 Full Hard?

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 Full Hard 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 Full Hard?

347 Full Hard is rated for continuous use to about 315°C (599 °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 Full Hard?

Yes — 347 Full Hard 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.