Stainless Steel 309HCb
UNS S30941
AISI 309HCb (S30941) combines the higher carbon of 309H with niobium stabilization in a 23Cr-13Ni austenitic matrix, so it holds elevated-temperature strength while resisting sensitization after welding.
Reference datasheet — 309HCb is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the ANN condition
309HCb tempers and conditions
309HCb is supplied in one standard condition, ANN. ANN is the default FabDigit quotes; the values on this page are for it.
Supply forms, finishes and certifications
Ways 309HCb is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
CD-BAR | Cold Drawn Bar | Supply form |
HF-BAR | Hot Finished Bar, Annealed | Supply form |
Tube-Ann | Seamless Tube, Annealed | Supply form |
WLD-PIPE | Welded Pipe, Annealed | Supply form |
CRA-SHT | Cold Rolled, Annealed Sheet / Strip | Surface finish |
HRAP-PLT | Hot Rolled, Annealed & Pickled Plate | Surface finish |
What is 309HCb?
AISI 309HCb (S30941) combines the higher carbon of 309H with niobium stabilization in a 23Cr-13Ni austenitic matrix, so it holds elevated-temperature strength while resisting sensitization after welding. It is used for high-temperature pressure equipment and petrochemical furnace tubing, supplied as plate, sheet, tube, welded pipe and hot-finished or cold-drawn bar. Annealed properties are around 275 MPa yield, 600 MPa tensile, 45% elongation and 165 HB (82 HRB), with service to 1000 °C. Availability is narrower than 309S or 310S, and long exposure at 700–850 °C still forms sigma phase. 309HCb has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,400°C (2,552 °F). 309HCb has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 77% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 200 GPa (29 Msi).
What is 309HCb used for?
- High-temperature pressure vessels
- Petrochemical furnace tubing
- Welded piping for hot gas service
- Reformer and cracking furnace hardware
- Boiler headers and supports
- Incinerator internals
- Heat-treat fixtures and hangers
Advantages
- High service temperature — 1,000°C (1,832 °F), better than 88% of stainless steel grades
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 86% of stainless steel grades
- Readily welded — 82/100, better than 84% of stainless steel grades
- Ductile — tolerates forming and impact — 45%, better than 76% of stainless steel grades
Limitations
- High embodied carbon — 5.6 kg CO₂/kg, worse than 83% of stainless steel grades
- Low strength — 275 MPa (39.9 ksi), worse than 77% of stainless steel grades
309HCb properties
Typical room-temperature values for 309HCb-ANN; bars are the position among stainless steel grades.
Physical3
309HCb has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical14
309HCb has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 77% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
309HCb is rated for continuous service to 1,000°C (1,832 °F). It conducts heat at 15.6 W/m·K (9.01 BTU/hr·ft·°F), better than 55% of stainless steel grades. Thermal expansion is 15 µm/m·K (8.33 µin/in·°F).
Electrical3
309HCb conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (66/100), better than 59% of stainless steel grades.
Sustainability4
Producing a kilogram of 309HCb takes about 57 MJ of energy and emits 5.6 kg of CO₂ — more than 62% of stainless steel grades. Typical recycled content is 60%.
Manufacturability7
309HCb's machinability is poor (33/100, worse than 57% of stainless steel grades); weldability very good (82/100); formability good (65/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. 309HCb is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 309HCb
Is 309HCb easy to machine?
Machine like 309/310 — rigid setups, sharp positive-rake carbide, heavy feeds and generous flood coolant; avoid dwelling because the alloy work-hardens quickly and Nb carbides accelerate tool wear.
Can 309HCb be welded?
Readily welded by GTAW/GMAW/SMAW with matching 309Cb/ER309 filler; no preheat and no post-weld heat treatment needed thanks to Nb stabilization, but keep interpass temperature low and heat input moderate to limit hot cracking and sigma formation.
Can 309HCb be formed, bent or molded?
Cold forms well but needs roughly 50 % higher press loads than carbon steel and generous bend radii; hot work at 1150–1200 °C and always solution anneal (1050–1120 °C, rapid cool) afterwards.
309HCb 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 gives the 'H' creep strength | 0.04 – 0.1 | 0.07 |
| Mn | ≤ 2 | 1.5 |
| Si | ≤ 0.75 | 0.5 |
| P | ≤ 0.05 | — |
| S | ≤ 0.03 | — |
| Cr | 22 – 24 | 23 |
| Ni | 12 – 16 | 13.5 |
| Nb10 × C minimum (Nb, or Nb+Ta), stabilizer | 0.4 – 1.1 | 0.75 |
| N | ≤ 0.1 | — |
| Fe | balance | — |
What surface finishes work on 309HCb?
Pickle and passivate per ASTM A967/A380 after hot work or welding; electropolish or mechanically polish for smooth surfaces — plating and painting are rarely used, anodizing is not applicable.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Organic Coating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel 309HCb in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S30941
How much does 309HCb cost?
309HCb is a premium-cost stainless steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
309HCb — frequently asked
What is 309HCb used for?
309HCb is typically used for high-temperature pressure vessels, petrochemical furnace tubing, welded piping for hot gas service, reformer and cracking furnace hardware, boiler headers and supports and incinerator internals. In short: stabilized high-carbon 309; code-rated hot pressure parts; no post-weld anneal.
What is the yield strength of 309HCb?
309HCb has a typical yield strength of 275 MPa (39.9 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 77% of stainless steel grades.
Is 309HCb easy to machine?
Not especially — machinability is rated poor (33/100, worse than 57% of stainless steel grades). Machine like 309/310 — rigid setups, sharp positive-rake carbide, heavy feeds and generous flood coolant; avoid dwelling because the alloy work-hardens quickly and Nb carbides accelerate tool wear.
Can 309HCb be welded?
Yes — weldability is rated very good (82/100). Readily welded by GTAW/GMAW/SMAW with matching 309Cb/ER309 filler; no preheat and no post-weld heat treatment needed thanks to Nb stabilization, but keep interpass temperature low and heat input moderate to limit hot cracking and sigma formation.
What surface finishes work on 309HCb?
Pickle and passivate per ASTM A967/A380 after hot work or welding; electropolish or mechanically polish for smooth surfaces — plating and painting are rarely used, anodizing is not applicable.
Can 309HCb be formed, bent or molded?
Cold forms well but needs roughly 50 % higher press loads than carbon steel and generous bend radii; hot work at 1150–1200 °C and always solution anneal (1050–1120 °C, rapid cool) afterwards.
What is the maximum service temperature of 309HCb?
309HCb is rated for continuous use to about 1,000°C (1,832 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 309HCb cost?
309HCb is a premium-cost stainless steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet and Strip — ASTM International (2023)
- ASTM A213/A213M — Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater and Heat-Exchanger Tubes (TP309HCb) — ASTM International (2022)
- ASTM A312/A312M — Seamless, Welded and Heavily Cold Worked Austenitic Stainless Steel Pipes — ASTM International (2022)
- ASME BPVC Section II Part D — Properties (Materials) — ASME (2023)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- SAE/ASTM Unified Numbering System (UNS) — S30940 / S30941 — SAE International (2019)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.