Stainless Steel 316Cb
UNS S31640 · EN 1.4580
AISI 316Cb (S31640) is a niobium-stabilized version of 316 austenitic stainless, in which NbC formation ties up carbon and prevents chromium carbide precipitation after welding or high-temperature exposure.
Reference datasheet — 316Cb 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 Annealed condition
316Cb tempers and conditions
316Cb is supplied in 7 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot Finished / Hot Rolled + Annealed bar (ASTM A276) | Economical large-diameter bar and shapes for machined weldments where surface finish and tight tolerance are not critical. | 245 | 560 | 45 | 160 HB | 2.3 % IACS |
AnnealedDefault solution annealed (1040–1120 °C, rapid cool), plate/sheet/bar | Standard stocked condition: maximum corrosion resistance, ductility and weldability for fabricated vessels and piping. | 250 | 570 | 45 | 155 HB | — |
annealed and cold drawn bar/wire | Pick for higher yield strength, straightness and good machined finish in fasteners, shafts and fittings. | 480 | 690 | 28 | 215 HB | — |
Quarter hard | Light cold-rolled temper when moderately higher strength is needed but some bending ductility must remain. | 560 | 900 | 12 | 25 HRC | 2.3 % IACS |
Half hard | Structural strip and springs where strength matters more than deep forming. | 800 | 1,070 | 8 | 32 HRC | 2.3 % IACS |
Three-quarter hard | High-strength strip for flat springs, clamps and shims with only simple bends. | 965 | 1,240 | 5 | 38 HRC | 2.3 % IACS |
cold rolled strip (ASTM A666 temper) | Maximum cold-worked strength/spring temper; essentially no formability beyond flat blanking. | 1,010 | 1,320 | 3 | 41 HRC | 2.3 % IACS |
Supply forms, finishes and certifications
Ways 316Cb is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Welded + PWHT-free | As Welded | Supply form |
What is 316Cb?
AISI 316Cb (S31640) is a niobium-stabilized version of 316 austenitic stainless, in which NbC formation ties up carbon and prevents chromium carbide precipitation after welding or high-temperature exposure. Engineers choose it for welded chemical process piping and vessels that cannot receive a post-weld solution anneal; it is available annealed, hot finished, cold drawn and in 1/4 to full hard tempers. Annealed values are roughly 250 MPa yield, 570 MPa tensile, 45 % elongation and 155 HB (82 HRB), with service to 870 °C. Where stabilization is not required, plain 316L is cheaper and more widely stocked. 316Cb has a density of 7.98 g/cm³ (0.288 lb/in³), heavier than 85% of stainless steel grades. It melts at 1,375°C (2,507 °F). 316Cb has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 91% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 195 GPa (28.3 Msi).
What is 316Cb used for?
- Welded chemical process piping
- High-temperature service vessels
- Heat exchanger shells and tubing
- Expansion bellows and joints
- Furnace and flue components
- Weld overlay and fabricated ducting
Advantages
- Readily welded — 90/100, better than 95% of stainless steel grades
- Forms and bends easily — 80/100, better than 93% of stainless steel grades
- High service temperature — 870°C (1,598 °F), better than 83% of stainless steel grades
- Ductile — tolerates forming and impact — 45%, better than 76% of stainless steel grades
Limitations
- Low strength — 250 MPa (36.3 ksi), worse than 91% of stainless steel grades
- High embodied carbon — 5.6 kg CO₂/kg, worse than 83% of stainless steel grades
316Cb properties
Typical room-temperature values for 316Cb-Annealed; bars are the position among stainless steel grades.
Physical3
316Cb has a density of 7.98 g/cm³ (0.288 lb/in³), heavier than 85% of stainless steel grades. It melts at 1,375°C (2,507 °F).
Mechanical16
316Cb has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 91% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
316Cb 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 µm/m·K (8.89 µin/in·°F).
Electrical3
316Cb conducts electricity at 2.3 % IACS, better than 55% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (70/100), better than 68% of stainless steel grades.
Sustainability4
Producing a kilogram of 316Cb takes about 75 MJ of energy and emits 5.6 kg of CO₂ — more than 84% of stainless steel grades. Typical recycled content is 60%.
Manufacturability7
316Cb's machinability is fair (38/100, better than 63% of stainless steel grades); weldability excellent (90/100); formability very good (80/100).
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. 316Cb is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 316Cb
Is 316Cb easy to machine?
Machine like 316 but expect harder NbC particles: rigid setups, sharp coated carbide, 25–60 m/min, heavy positive feed to avoid work-hardened glaze, flood coolant.
Can 316Cb be welded?
Excellent with GTAW/GMAW/SMAW using ER/E 318 (Nb-bearing) or 316L filler; no post-weld anneal needed for sensitization control, keep heat input moderate and interpass low to limit distortion.
Can 316Cb be formed, bent or molded?
Cold forms and deep draws well in the annealed temper but work-hardens rapidly — allow 30–50% more press force than carbon steel and interstage anneal for severe draws; hot work 1150–1200 °C, then solution anneal.
316Cb 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 |
|---|---|---|
| CNb ≥ 10 × C required | ≤ 0.08 | 0.05 |
| Mn | ≤ 2 | 1.5 |
| Si | ≤ 0.75 | 0.5 |
| P | ≤ 0.05 | — |
| S | ≤ 0.03 | — |
| Cr | 16 – 18 | 17 |
| Ni | 10 – 14 | 12 |
| Mo | 2 – 3 | 2.5 |
| Nb10 × C min; Nb (+Ta) stabilizer | ≤ 1.1 | 0.6 |
| N | ≤ 0.1 | — |
| Fe | balance | — |
What surface finishes work on 316Cb?
Pickle and passivate per ASTM A967 (or electropolish) after welding to restore the passive film; not anodizable, takes mechanical No.4 to No.8 mirror finishes.
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 316Cb in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S31640
- EN / DIN / Werkstoff-Nr.
- 1.4580
How much does 316Cb cost?
316Cb 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.
316Cb — frequently asked
What is 316Cb used for?
316Cb is typically used for welded chemical process piping, high-temperature service vessels, heat exchanger shells and tubing, expansion bellows and joints, furnace and flue components and weld overlay and fabricated ducting. In short: nb-stabilized 316; no post-weld anneal needed; resists intergranular attack.
What is the yield strength of 316Cb?
316Cb has a typical yield strength of 250 MPa (36.3 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 91% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 316Cb easy to machine?
Not especially — machinability is rated fair (38/100, better than 63% of stainless steel grades). Machine like 316 but expect harder NbC particles: rigid setups, sharp coated carbide, 25–60 m/min, heavy positive feed to avoid work-hardened glaze, flood coolant.
Can 316Cb be welded?
Yes — weldability is rated excellent (90/100). Excellent with GTAW/GMAW/SMAW using ER/E 318 (Nb-bearing) or 316L filler; no post-weld anneal needed for sensitization control, keep heat input moderate and interpass low to limit distortion.
What surface finishes work on 316Cb?
Pickle and passivate per ASTM A967 (or electropolish) after welding to restore the passive film; not anodizable, takes mechanical No.4 to No.8 mirror finishes.
Can 316Cb be formed, bent or molded?
Cold forms and deep draws well in the annealed temper but work-hardens rapidly — allow 30–50% more press force than carbon steel and interstage anneal for severe draws; hot work 1150–1200 °C, then solution anneal.
What is the maximum service temperature of 316Cb?
316Cb 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.
How much does 316Cb cost?
316Cb 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 (2022)
- ASTM A276/A276M — Stainless Steel Bars and Shapes — ASTM (2017)
- ASTM A666 — Annealed or Cold-Worked Austenitic Stainless Steel Sheet, Strip, Plate and Flat Bar — ASTM (2015)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.13B — Corrosion: Materials — ASM International (2005)
- SAE/ASTM Unified Numbering System for Metals and Alloys (UNS S31640) — SAE/ASTM (2017)
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.