Stainless Steel 309Cb-CD (Cold drawn)
Supply condition
UNS S30940
Use for machined shafts, bolting and fixture pins where tighter tolerance and higher yield are wanted.
Values for the CD condition
Other 309Cb tempers and conditions
309Cb is listed in 5 conditions; see the grade overview at 309Cb.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault solution annealed (1040–1120 °C, rapid cool) | Standard mill condition for plate, sheet, bar, pipe and fittings; maximum ductility and corrosion resistance. | 310 | 620 | 45 | 165 HB | — |
As-welded deposit | Condition of dissimilar-metal joints and stainless overlays on carbon/low-alloy steel; Nb stabilization is what lets the joint go into service unannealed. | 400 | 590 | 32 | 180 HB | 2.2 % IACS |
CDThis page Cold drawn | Use for machined shafts, bolting and fixture pins where tighter tolerance and higher yield are wanted. | 480 | 720 | 30 | 15 HRC | 2.2 % IACS |
Quarter hard | Special-order strip/sheet temper when higher room-temperature strength is needed and forming demands are mild. | 515 | 860 | 20 | 25 HRC | 2.2 % IACS |
Half hard | Rarely stocked; only for flat springs/clips where strength outweighs formability and no hot service is involved. | 760 | 1,035 | 10 | 32 HRC | 2.2 % IACS |
What is 309Cb-CD?
309Cb-CD is 309Cb supplied in the CD condition — use for machined shafts, bolting and fixture pins where tighter tolerance and higher yield are wanted. 309Cb-CD has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 75% of stainless steel grades. Elongation at break is 30% and the elastic modulus is 200 GPa (29 Msi). 309Cb-CD has a density of 7.98 g/cm³ (0.288 lb/in³), heavier than 85% of stainless steel grades. It melts at 1,400°C (2,552 °F). Annealed is the default condition FabDigit quotes; CD is available on request or by drawing note.
Advantages
- High service temperature — 870°C (1,598 °F), better than 83% of stainless steel grades
- High strength — 480 MPa (69.6 ksi), better than 75% of stainless steel grades
309Cb-CD properties
Typical room-temperature values for 309Cb-CD; 23 are specific to this condition. Other listed values are 309Cb reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
309Cb-CD has a density of 7.98 g/cm³ (0.288 lb/in³), heavier than 85% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical15
309Cb-CD has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 75% of stainless steel grades. Elongation at break is 30% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
309Cb-CD is rated for continuous service to 870°C (1,598 °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 14.9 µm/m·K (8.28 µin/in·°F).
Electrical3
309Cb-CD conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (65/100), better than 56% of stainless steel grades.
Sustainability4
Producing a kilogram of 309Cb-CD takes about 60 MJ of energy and emits 4.8 kg of CO₂ — more than 70% of stainless steel grades. Typical recycled content is 60%.
Manufacturability7
309Cb-CD's machinability is fair (42/100, better than 79% of stainless steel grades); weldability very good (78/100); formability fair (40/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 309Cb-CD
Is 309Cb easy to machine?
Machine like 310: rigid setups, positive-rake sharp carbide, heavy feeds at low-to-moderate speed (~25–40 % of 1212 rates), flood coolant, and avoid dwelling — the alloy work-hardens fast and Nb carbides are abrasive.
Can 309Cb be welded?
Readily welded by GTAW/GMAW/SMAW with matching 309Cb, ER309LNb or 309L filler; no post-weld anneal is required thanks to Nb stabilization, but keep interpass temperature low and avoid long holds at 700–850 °C to limit sigma phase.
Can 309Cb be formed, bent or molded?
Cold forms and roll-bends well but needs about 50 % more press force than carbon steel with large springback; hot work at 1150–1200 °C and finish above 950 °C, then solution anneal at 1040–1120 °C with rapid cooling.
What surface finishes work on 309Cb?
Pickle and passivate (ASTM A967) or grit-blast plus acid clean after hot forming; can be ground, brushed or electropolished — anodizing does not apply, and high-temperature service will grow a tight dark oxide scale.
309Cb 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 is set at ≥10×C | ≤ 0.08 | 0.06 |
| Si | ≤ 1 | 0.6 |
| Mn | ≤ 2 | 1.5 |
| P | ≤ 0.05 | — |
| S | ≤ 0.03 | — |
| Cr | 22 – 24 | 23 |
| Ni | 12 – 15 | 13.5 |
| NbNb+Ta, minimum 10×C (stabilizer) | ≤ 1.1 | 0.8 |
| Nreported when specified | ≤ 0.1 | — |
| Fe | balance | — |
309Cb-CD — frequently asked
What is 309Cb-CD used for?
309Cb-CD is typically used for high-temperature welded assemblies, furnace components and heat exchanger tubing. In short: nb-stabilized 309; sensitization-free after welding; 1000 °C service ceiling.
What is the yield strength of 309Cb-CD?
309Cb-CD has a typical yield strength of 480 MPa (69.6 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 75% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is 309Cb-CD easy to machine?
Not especially — machinability is rated fair (42/100, better than 79% of stainless steel grades). Machine like 310: rigid setups, positive-rake sharp carbide, heavy feeds at low-to-moderate speed (~25–40 % of 1212 rates), flood coolant, and avoid dwelling — the alloy work-hardens fast and Nb carbides are abrasive.
Can 309Cb-CD be welded?
Yes — weldability is rated very good (78/100). Readily welded by GTAW/GMAW/SMAW with matching 309Cb, ER309LNb or 309L filler; no post-weld anneal is required thanks to Nb stabilization, but keep interpass temperature low and avoid long holds at 700–850 °C to limit sigma phase.
What surface finishes work on 309Cb-CD?
Pickle and passivate (ASTM A967) or grit-blast plus acid clean after hot forming; can be ground, brushed or electropolished — anodizing does not apply, and high-temperature service will grow a tight dark oxide scale.
Can 309Cb-CD be formed, bent or molded?
Cold forms and roll-bends well but needs about 50 % more press force than carbon steel with large springback; hot work at 1150–1200 °C and finish above 950 °C, then solution anneal at 1040–1120 °C with rapid cooling.
What is the maximum service temperature of 309Cb-CD?
309Cb-CD 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 309Cb Annealed and 309Cb-CD?
Annealed is the default condition — standard mill condition for plate, sheet, bar, pipe and fittings; maximum ductility and corrosion resistance. CD: use for machined shafts, bolting and fixture pins where tighter tolerance and higher yield are wanted. Yield strength is 310 MPa in Annealed versus 480 MPa in CD.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet and Strip (S30940) — ASTM International (2023)
- ASTM A479/A479M — Stainless Steel Bars and Shapes for Boilers and Pressure Vessels — ASTM International (2021)
- ASTM A312/A312M — Seamless, Welded and Heavily Cold Worked Austenitic Stainless Steel Pipes — ASTM International (2022)
- AWS A5.9 / A5.4 — Bare and Covered Corrosion-Resisting Chromium-Nickel Electrodes (309Cb/309LNb) — American Welding Society (2017)
- 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)
- 309/309S/309Cb heat-resisting stainless product data — Cleveland-Cliffs (AK Steel) / Outokumpu (2021)
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.