Stainless Steel 904L
AISI/SAE 904L · UNS N08904 · ASTM A240/A276 · EN 1.4539, X1NiCrMoCu25-20-5 · GB 015Cr21Ni26Mo5Cu2, 015Cr20Ni25Mo4.5Cu
904L (N08904, 1.4539) is a low-carbon superaustenitic stainless with high nickel, chromium, molybdenum and copper, supplied to A240/A276.
Values for the Solution Annealed condition
904L tempers and conditions
904L is supplied in 4 conditions, soft to hard. Solution Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
mill annealed bar / hot-finished and annealed product | Hot-finished bar, billet and forgings supplied annealed; same corrosion performance, slightly lower strength than cold-worked forms. | 240 | 560 | 45 | 150 HB | 1.7 % IACS |
Solution AnnealedDefault 1100–1150 °C, rapid quench (plate, sheet, tube, forgings) | Standard supply condition for all corrosion-service product forms — maximum corrosion resistance and ductility. | 260 | 590 | 42 | 155 HB | 1.7 % IACS |
cold drawn / cold finished bar and tube (lightly work hardened) | Choose for tight tolerance shafts, fasteners and small-bore tube where higher yield strength and better surface finish are needed. | 550 | 750 | 25 | 230 HB | — |
cold rolled strip/sheet, temper rolled (≈1/4 to 1/2 hard) | Strip/sheet supplied work hardened for springs, gaskets and stamped parts needing higher strength; solution anneal after severe forming for best corrosion resistance. | 620 | 820 | 15 | 26 HRC | 1.7 % IACS |
What is 904L?
904L (N08904, 1.4539) is a low-carbon superaustenitic stainless with high nickel, chromium, molybdenum and copper, supplied to A240/A276. Engineers use it for sulfuric and phosphoric acid duty and chloride-bearing process streams where 260 MPa yield, 590 MPa tensile and 42 % elongation are sufficient; it is available annealed, solution annealed, cold drawn or cold rolled hard as plate, sheet, bar and tube. Strength is well below duplex grades, the nickel content makes it costly, and it work-hardens quickly during machining. For higher chloride pitting resistance, step up to 254 SMO or AL-6XN. 904L has a density of 8 g/cm³ (0.289 lb/in³), heavier than 92% of stainless steel grades. It melts at 1,300°C (2,372 °F). 904L has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 590 MPa (85.6 ksi) — weaker than 84% of stainless steel grades. Elongation at break is 42% and the elastic modulus is 195 GPa (28.3 Msi).
What is 904L used for?
- Sulfuric acid pumps and valves
- Pickling line tanks and fixtures
- Phosphoric acid heat exchangers
- Flue-gas desulfurization scrubbers
- Chemical process piping and vessels
- Seawater condenser tubing
- Pulp bleaching plant equipment
Advantages
- Good corrosion resistance — 82/100, better than 90% of stainless steel grades
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 86% of stainless steel grades
- Forms and bends easily — 72/100, better than 84% of stainless steel grades
Limitations
- Poor heat conductor — 12 W/m·K (6.93 BTU/hr·ft·°F), worse than 93% of stainless steel grades
- Low electrical conductivity — 1.7 % IACS, worse than 93% of stainless steel grades
- Low strength — 260 MPa (37.7 ksi), worse than 84% of stainless steel grades
- High embodied carbon — 5.6 kg CO₂/kg, worse than 83% of stainless steel grades
- Limited service temperature — 400°C (752 °F), worse than 78% of stainless steel grades
904L properties
Typical room-temperature values for 904L-Solution Annealed; bars are the position among stainless steel grades.
Physical3
904L has a density of 8 g/cm³ (0.289 lb/in³), heavier than 92% of stainless steel grades. It melts at 1,300°C (2,372 °F).
Mechanical16
904L has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 590 MPa (85.6 ksi) — weaker than 84% of stainless steel grades. Elongation at break is 42% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
904L is rated for continuous service to 400°C (752 °F). It conducts heat at 12 W/m·K (6.93 BTU/hr·ft·°F), worse than 93% of stainless steel grades. Thermal expansion is 15.3 µm/m·K (8.5 µin/in·°F).
Electrical3
904L conducts electricity at 1.7 % IACS, worse than 93% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (82/100), better than 90% of stainless steel grades.
Sustainability4
Producing a kilogram of 904L takes about 78 MJ of energy and emits 5.6 kg of CO₂ — more than 87% of stainless steel grades. Typical recycled content is 55%.
Manufacturability7
904L's machinability is poor (28/100, worse than 79% of stainless steel grades); weldability very good (78/100); formability very good (72/100).
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. 904L is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 904L
Is 904L easy to machine?
Gummy and strongly work hardening — use rigid setups, positive-rake coated carbide, low speed / heavy positive feed, generous flood coolant and avoid dwelling or re-cutting in the hardened layer.
Can 904L be welded?
Readily welded by GTAW/GMAW/SMAW with no preheat and low interpass temperature; use overalloyed filler (ER/E 385 = 904L-type or Ni-base 625/C-276) to avoid Mo-depleted dendrite cores, and keep heat input low with backing gas.
Can 904L be formed, bent or molded?
Very ductile but needs ~50% higher forming loads than 304 with strong springback; hot work 1150–900 °C then solution anneal and quench to restore corrosion resistance.
Manufacturability
The process limits FabDigit applies to 904L. Every 904L part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Poor28 / 100 |
|---|---|
| ISO material group | M.1 |
| Cutting speed (rough / finish) | 150 / 180 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1.5 mm |
| Drill depth limit | 4× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Better72 / 100 |
|---|---|
| Weldability | Better78 / 100 |
| Bendable | Yes |
904L 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 |
|---|---|---|
| Cextra-low carbon | ≤ 0.02 | 0.01 |
| SiEN 1.4539 limits Si ≤ 0.70 | ≤ 1 | 0.4 |
| Mn | ≤ 2 | 1.4 |
| PEN 1.4539: ≤ 0.030 | ≤ 0.05 | 0.03 |
| SEN 1.4539: ≤ 0.010 | ≤ 0.04 | 0 |
| Cr | 19 – 23 | 20 |
| Ni | 23 – 28 | 25 |
| Mo | 4 – 5 | 4.5 |
| Cuimproves resistance in sulfuric acid | 1 – 2 | 1.5 |
| NEN 1.4539 limit | ≤ 0.1 | 0.05 |
| Fe | balance |
What surface finishes work on 904L?
Pickle and passivate (nitric or citric) after welding, remove all heat tint by grinding/blasting or pickling paste; electropolishes to low-Ra hygienic finishes and cannot be anodized.
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).
Plating
Organic Coating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel 904L in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- N08904
- ASTM
- A240/A276
- EN / DIN / Werkstoff-Nr.
- 1.4539X1NiCrMoCu25-20-5
- GB (China)
- 015Cr21Ni26Mo5Cu2015Cr20Ni25Mo4.5Cu
- Trade names
- Cronifer 1925LCUranus B6
- Similar grades
- 015Cr20Ni25Mo4.5CuN
How much does 904L cost?
904L is a premium-cost stainless steel ($$$), cheaper than about 58% 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.
904L — frequently asked
What is 904L used for?
904L is typically used for sulfuric acid pumps and valves, pickling line tanks and fixtures, phosphoric acid heat exchangers, flue-gas desulfurization scrubbers, chemical process piping and vessels and seawater condenser tubing. In short: super-austenitic chemical stainless.
What is the yield strength of 904L?
904L has a typical yield strength of 260 MPa (37.7 ksi) and a tensile strength of 590 MPa (85.6 ksi) — weaker than 84% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is 904L easy to machine?
Not especially — machinability is rated poor (28/100, worse than 79% of stainless steel grades). Gummy and strongly work hardening — use rigid setups, positive-rake coated carbide, low speed / heavy positive feed, generous flood coolant and avoid dwelling or re-cutting in the hardened layer.
Can 904L be welded?
Yes — weldability is rated very good (78/100). Readily welded by GTAW/GMAW/SMAW with no preheat and low interpass temperature; use overalloyed filler (ER/E 385 = 904L-type or Ni-base 625/C-276) to avoid Mo-depleted dendrite cores, and keep heat input low with backing gas.
What surface finishes work on 904L?
Pickle and passivate (nitric or citric) after welding, remove all heat tint by grinding/blasting or pickling paste; electropolishes to low-Ra hygienic finishes and cannot be anodized.
Can 904L be formed, bent or molded?
Very ductile but needs ~50% higher forming loads than 304 with strong springback; hot work 1150–900 °C then solution anneal and quench to restore corrosion resistance.
What is the maximum service temperature of 904L?
904L is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 904L cost?
904L is a premium-cost stainless steel ($$$), cheaper than about 58% 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.
Can FabDigit make parts in 904L?
Yes — 904L is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A240/A240M — Cr and Cr-Ni Stainless Plate, Sheet and Strip — ASTM International (2023)
- ASTM B625 / B649 — UNS N08904 plate, sheet, strip and bar — ASTM International (2022)
- EN 10088-1/-2 — Stainless steels, grade 1.4539 (X1NiCrMoCu25-20-5) — CEN (2014)
- 904L / 1.4539 super-austenitic stainless datasheet — Outokumpu (2023)
- Sanicro 28 / 904L-type alloy technical data — Alleima (Sandvik) (2022)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
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.