Stainless Steel S33550-ANN (Annealed)
Heat-treated state · default condition
UNS S33550
Standard supply condition for sheet, plate, bar and tube; best ductility, weldability and high-temperature stability.
Values for the ANN condition
Other S33550 tempers and conditions
S33550 is listed in 5 conditions; see the grade overview at S33550.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot Finished | Heavy plate, forged bar and rings where dimensional tolerance is coarse but section is thick. | 300 | 670 | 42 | 175 HB | 1.5 % IACS |
ANNDefaultThis page Annealed | Standard supply condition for sheet, plate, bar and tube; best ductility, weldability and high-temperature stability. | 310 | 690 | 45 | 170 HB | 1.5 % IACS |
Cold Rolled + Annealed | Thin gauge sheet and strip for muffles, radiant tube liners and formed furnace hardware needing a clean surface. | 320 | 700 | 45 | 175 HB | 1.5 % IACS |
As-welded deposit | Property set for fabricated furnace assemblies joined with matching or Ni-base filler and used directly in service. | 340 | 650 | 32 | 185 HB | 1.5 % IACS |
Cold drawn | Choose for close-tolerance bar and fastener stock; higher strength but lower ductility and reduced hot-forming reserve. | 550 | 830 | 25 | 22 HRC | 1.5 % IACS |
What is S33550-ANN?
S33550-ANN is S33550 heat treated to ANN — standard supply condition for sheet, plate, bar and tube; best ductility, weldability and high-temperature stability. S33550-ANN has a yield strength of 310 MPa (45 ksi) and a tensile strength of 690 MPa (100 ksi) — weaker than 63% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 200 GPa (29 Msi). S33550-ANN has a density of 8.14 g/cm³ (0.294 lb/in³), heavier than 99% of stainless steel grades. It melts at 1,330°C (2,426 °F).
Advantages
- High service temperature — 1,150°C (2,102 °F), better than 99% of stainless steel grades
- Ductile — tolerates forming and impact — 45%, better than 76% of stainless steel grades
Limitations
- Low electrical conductivity — 1.5 % IACS, worse than 100% of stainless steel grades
- High embodied carbon — 8.5 kg CO₂/kg, worse than 99% of stainless steel grades
- Poor heat conductor — 11.5 W/m·K (6.64 BTU/hr·ft·°F), worse than 97% of stainless steel grades
- Difficult to machine — 25/100, worse than 88% of stainless steel grades
S33550-ANN properties
Typical room-temperature values for S33550-ANN; 22 are specific to this condition. Other listed values are S33550 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
S33550-ANN has a density of 8.14 g/cm³ (0.294 lb/in³), heavier than 99% of stainless steel grades. It melts at 1,330°C (2,426 °F).
Mechanical16
S33550-ANN has a yield strength of 310 MPa (45 ksi) and a tensile strength of 690 MPa (100 ksi) — weaker than 63% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 200 GPa (29 Msi).
Thermal5
S33550-ANN is rated for continuous service to 1,150°C (2,102 °F). It conducts heat at 11.5 W/m·K (6.64 BTU/hr·ft·°F), worse than 97% of stainless steel grades. Thermal expansion is 14.4 µm/m·K (8 µin/in·°F).
Electrical3
S33550-ANN conducts electricity at 1.5 % IACS, worse than 100% of stainless steel grades.
Chemical & Environmental2
Corrosion resistance is very good (72/100), better than 73% of stainless steel grades.
Sustainability4
Producing a kilogram of S33550-ANN takes about 115 MJ of energy and emits 8.5 kg of CO₂ — more than 100% of stainless steel grades. Typical recycled content is 40%.
Manufacturability6
S33550-ANN's machinability is poor (25/100, worse than 88% of stainless steel grades); weldability very good (75/100); formability good (65/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with S33550-ANN
Is S33550 easy to machine?
Machine like a nickel alloy: rigid setup, positive-rake sharp carbide, slow speed (~15–25 m/min) with heavy positive feed and flood coolant to cut under the work-hardened layer.
Can S33550 be welded?
Readily GTAW/GMAW/SMAW welded with matching or Ni-Cr-Mo filler; no preheat, low interpass temperature, no PWHT normally required, avoid heavy restraint and high heat input.
Can S33550 be formed, bent or molded?
Very ductile but strongly work hardening — allow extra press tonnage, generous bend radii and interstage solution anneals; hot work 1150–900 °C followed by rapid cooling.
What surface finishes work on S33550?
Pickle or grit blast plus passivation to remove heat-treat scale; takes a good mechanical polish, plating is rarely used and no anodizing response.
S33550 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 |
|---|---|---|
| Nifamily nominal (alloy 333 type); confirm against purchase specification | 42 – 47 | 45 |
| Croxidation/carburization resistance | 24 – 27 | 25 |
| Mo | 2.5 – 4 | 3 |
| W | 2.5 – 4 | 3 |
| Co | 2.5 – 4 | 3 |
| Sikey for carburization resistance | 0.75 – 1.5 | 1.2 |
| Mn | ≤ 2 | 1 |
| C | ≤ 0.08 | 0.05 |
| P | ≤ 0.03 | — |
| S | ≤ 0.02 | — |
| Febalance, nominally 16–20 % | balance | — |
S33550-ANN — frequently asked
What is S33550-ANN used for?
S33550-ANN is typically used for furnace hardware, thermal-processing fixtures, carburizing and nitriding furnace retorts, radiant tube components, heat-treatment baskets and trays and muffle and retort liners. In short: carburizing-atmosphere furnace alloy; 1150 °C service austenitic; machines like nickel alloy.
What is the yield strength of S33550-ANN?
S33550-ANN has a typical yield strength of 310 MPa (45 ksi) and a tensile strength of 690 MPa (100 ksi) — weaker than 63% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is S33550-ANN easy to machine?
Not especially — machinability is rated poor (25/100, worse than 88% of stainless steel grades). Machine like a nickel alloy: rigid setup, positive-rake sharp carbide, slow speed (~15–25 m/min) with heavy positive feed and flood coolant to cut under the work-hardened layer.
Can S33550-ANN be welded?
Yes — weldability is rated very good (75/100). Readily GTAW/GMAW/SMAW welded with matching or Ni-Cr-Mo filler; no preheat, low interpass temperature, no PWHT normally required, avoid heavy restraint and high heat input.
What surface finishes work on S33550-ANN?
Pickle or grit blast plus passivation to remove heat-treat scale; takes a good mechanical polish, plating is rarely used and no anodizing response.
Can S33550-ANN be formed, bent or molded?
Very ductile but strongly work hardening — allow extra press tonnage, generous bend radii and interstage solution anneals; hot work 1150–900 °C followed by rapid cooling.
What is the maximum service temperature of S33550-ANN?
S33550-ANN is rated for continuous use to about 1,150°C (2,102 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between S33550-ANN and S33550-CD?
ANN is the default condition — standard supply condition for sheet, plate, bar and tube; best ductility, weldability and high-temperature stability. CD: choose for close-tolerance bar and fastener stock; higher strength but lower ductility and reduced hot-forming reserve. Yield strength is 310 MPa in ANN versus 550 MPa in CD.
Sources
- ASM Handbook Vol.1 — Heat-Resistant Austenitic Steels and Iron-Nickel-Chromium Alloys — ASM International (1990)
- ASM Handbook Vol.13B — Corrosion in High-Temperature Environments — ASM International (2005)
- Ni-Cr-Fe furnace alloy (alloy 333 type) technical data — Rolled Alloys (2022)
- Metals & Alloys in the Unified Numbering System (UNS) — SAE/ASTM (2017)
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.