Stainless Steel S33550
UNS S33550
S33550 is a high nickel-chromium austenitic heat- and corrosion-resistant stainless alloy intended for furnace and thermal-processing equipment exposed to carburizing and nitriding atmospheres.
Reference datasheet — S33550 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
S33550 tempers and conditions
S33550 is supplied in 5 conditions, soft to hard. ANN is the default FabDigit quotes; the values on this page are for it.
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 |
ANNDefault 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?
S33550 is a high nickel-chromium austenitic heat- and corrosion-resistant stainless alloy intended for furnace and thermal-processing equipment exposed to carburizing and nitriding atmospheres. In the annealed condition it is rated at 310 MPa yield, 690 MPa tensile and 45% elongation at about 170 HB (86 HRB), with a maximum service temperature of 1150 °C; it is held annealed, hot finished, cold drawn, cold-rolled annealed and as-welded. The nickel content raises cost and makes the alloy behave like a nickel-base alloy in the cut, and it work hardens strongly during forming. Where carburizing resistance is not the controlling factor, 310S is the lower-cost heat-resistant austenitic. S33550 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). S33550 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).
What is S33550 used for?
- Furnace hardware
- Thermal-processing fixtures
- Carburizing and nitriding furnace retorts
- Radiant tube components
- Heat-treatment baskets and trays
- Muffle and retort liners
- Burner and combustion hardware
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 properties
Typical room-temperature values for S33550-ANN; bars are the position among stainless steel grades.
Physical3
S33550 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 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 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 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 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'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. 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. S33550 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S33550
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.
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 |
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.
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
How much does S33550 cost?
S33550 is a high-cost stainless steel ($$$$), pricier than about 78% 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.
S33550 — frequently asked
What is S33550 used for?
S33550 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?
S33550 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 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 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?
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 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?
S33550 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.
How much does S33550 cost?
S33550 is a high-cost stainless steel ($$$$), pricier than about 78% 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
- 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; 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.