Table of Contents
- SS 904L Washers Overview
- SS 904L Washers Specifications
- SS 904L Technical Properties & Composition
- SS 904L vs. SS 316L
- Why Industries Prefer SS 904L Washers
- Types of SS 904L Washers
- Key Technical Advantages
- Key Applications of SS 904L Washers
- Quality Testing & Inspection
- Global Export Markets
- Frequently Asked Questions
- Contact Aurum Overseas
SS 904L Washers Suppliers & Exporters
Aurum Overseas is a global SS 904L Washers Supplier and SS 904L Washers Exporter, offering high-strength super austenitic fasteners for extreme corrosive processing environments. Engineered in styles such as Plain Washers, Spring Washers, Lock Washers, Square Washers, and Conical Washers, our hardware conforms strictly to ASME B18.21.1, DIN 125, and ISO 7089 standards.
Formulated with 19–23% chromium, 23–28% nickel, 4–5% molybdenum, and 1–2% copper, these UNS N08904 Washers deliver exceptional resistance to warm sulfuric acid, phosphoric acid, and pitting. As a trusted SS 904L Washers Exporter, we supply fully certified, precision-stamped washers with fast shipping across North America, Europe, the Middle East, and the Asia-Pacific region.
SS 904L Washers Specifications
| Parameter | Technical Specification / Standard Range |
|---|---|
| Material Grade | Stainless Steel 904L (UNS N08904) |
| UNS Designation | UNS N08904 Washers |
| Werkstoff Number | 1.4539 (X1NiCrMoCu25-20-5) |
| Manufacturing Standards | ASTM A240 / ASME SA240, ASTM B625 |
| Dimensional Specifications | ASME B18.21.1, DIN 125 A/B, DIN 127 B, DIN 9021, ISO 7089, ISO 7090 |
| Washer Types | Plain Flat Washers, Heavy Duty Structural, Spring Lock, Belleville Washers, Tab Washers |
| Size Range | Imperial: #4 to 4" NB | Metric: M3 to M100 |
| Thickness Range | 0.5 mm to 12 mm (Custom gauges available on order) |
| Hardness Range | Annealed: HRB 70–90 typical |
| Surface Finishes | Bright Annealed, Passivated, Pickled, Electro-polished, PTFE Coated |
| Certification | EN 10204 3.1 MTR, PMI Testing Report, Hardness Verification |
SS 904L Technical Properties & Composition
Chemical Composition of UNS N08904 Washers (%)
| Element | SS 904L (UNS N08904) |
|---|---|
| Carbon (C) | 0.020 max |
| Manganese (Mn) | 2.0 max |
| Silicon (Si) | 1.0 max |
| Phosphorus (P) | 0.045 max |
| Sulfur (S) | 0.035 max |
| Chromium (Cr) | 19.0 – 23.0 |
| Molybdenum (Mo) | 4.0 – 5.0 |
| Nickel (Ni) | 23.0 – 28.0 |
| Copper (Cu) | 1.0 – 2.0 |
| Iron (Fe) | Balance |
Mechanical Properties of UNS N08904 Washers
| Property / Parameter | SS 904L (UNS N08904) |
|---|---|
| Tensile Strength (MPa) min | 490 |
| Yield Strength 0.2% Proof (MPa) min | 220 |
| Elongation (% in 50mm) min | 35 |
| Rockwell Hardness B (HR B) max | 70–90 typical |
Equivalent Grades of SS 904L Washers
| Standard / System | SS 904L |
|---|---|
| UNS Designation | N08904 |
| Werkstoff Nr. | 1.4539 |
| Euronorm Name | X1NiCrMoCu25-20-5 |
SS 904L vs. SS 316L
| Feature | SS 904L (UNS N08904) | SS 316L (UNS S31603) |
|---|---|---|
| Alloy Classification | Super Austenitic Stainless Steel | Standard Marine-Grade Austenitic |
| Copper Addition | 1.0 – 2.0% Copper for acid immunity | No Copper content |
| Nickel Content | High Nickel (23.0 – 28.0%) | Moderate Nickel (10.0 – 14.0%) |
| Molybdenum Level | 4.0 – 5.0% Mo for high PREN | 2.0 – 3.0% Mo |
| Sulfuric Acid Performance | Outstanding in all concentrations up to 40°C | Poor performance in concentrated acids |
| Pitting Resistance (PREN) | PREN ≥ 34 (High localized resistance) | PREN ≈ 25 |
Why Industries Prefer SS 904L Washers
Sulfuric Acid Immunity: Resists strong reducing acids across all concentrations up to moderate temperatures.
Pitting & Crevice Protection: High molybdenum (4–5%) and chromium (19–23%) content prevent localized corrosion in warm halide solutions.
Stress Corrosion Cracking Resistance: Elevated 23–28% nickel matrix eliminates chloride-induced cracking in heated process lines.
Non-Magnetic Integrity: Maintains complete non-magnetic properties even after cold forming and heavy stamping.
Long Service Life: Eliminates washer degradation and joint leaks in aggressive chemical, pulp, and marine environments.
Types of SS 904L Washers
Aurum Overseas supplies a comprehensive range of stainless steel washer configurations manufactured according to standard DIN, ASME, and ISO dimensional tolerances for multiple engineering assemblies.
SS 904L Plain Washers
SS 904L Spring Washers
SS 904L Lock Washers
SS 904L Square Washers
SS 904L Conical Washers
Key Technical Advantages
Copper-Alloyed Matrix
Contains 1–2% copper, granting complete passive stability in warm sulfuric, phosphoric, and formic acids.
High PREN Value
Delivers a Pitting Resistance Equivalent Number (PREN ≥ 34) to withstand aggressive seawater and chloride chemistry.
Low Carbon Chemistry
Ultra-low carbon content (0.020% max) prevents intergranular carbide precipitation during welding.
High Structural Ductility
Exhibits 35% minimum elongation, providing tight bolt seating and uniform load distribution under torque.
Non-Magnetic Behavior
Fully austenitic structure remains non-magnetic across cryogenic and elevated operating temperatures.
Key Applications of SS 904L Washers
| Industry Sector | Application | Operating Environment |
|---|---|---|
| Chemical Processing | Flange bolting, heat exchangers, and storage tanks | Exposure to hot, concentrated sulfuric, phosphoric, and organic acids |
| Fertilizer Manufacturing | Reactor vessel fasteners and evaporator assemblies | Harsh wet-process acids and aggressive fluoride chemicals |
| Pulp & Paper | Bleach plant washing systems and bleach tower hardware | Direct contact with chlorine dioxide solutions and corrosive acid washes |
| Marine & Offshore | Desalination units, reverse osmosis equipment, and scrubbers | Continuous exposure to high-salinity seawater and chloride-rich environments |
| Oil & Gas Refining | Sour gas scrubbers and alkylation unit piping joints | Contact with hydrogen sulfide, acidic vapors, and heavy chloride loads |
Quality Testing & Inspection
As a leading SS 904L Washers Supplier, Aurum Overseas conducts comprehensive testing on all shipments:
- Chemical Verification: XRF Positive Material Identification (PMI) to confirm 23–28% nickel, 4–5% molybdenum, and 1–2% copper.
- Mechanical Property Tests: Tensile (490 MPa min), yield strength (220 MPa min), and elongation checks (35% min) per ASTM A240.
- Corrosion Resistance Audit: ASTM G48 pitting and crevice corrosion testing to confirm integrity in chloride environments.
- Dimensional Inspection: Laser micrometer validation of thickness, inner diameter, and outer diameter tolerances to ASME B18.21.1 and DIN 125.
- Certified Traceability: Shipped with EN 10204 3.1 Material Test Reports for total mill heat traceability.
Global Export Markets
Aurum Overseas, a global SS 904L Washers Exporter, supplies certified UNS N08904 Washers to processing facilities worldwide:
USA
Canada
Mexico
Germany
United
Kingdom
France
Italy
Netherlands
Norway
UAE
Saudi
Arabia
Qatar
Kuwait
Oman
Singapore
Malaysia
Australia
Frequently Asked Questions
SS 904L includes 1–2% copper alongside 23–28% nickel. This specific combination provides resistance to sulfuric acid across all concentrations up to 40°C.
No, UNS N08904 Washers are super austenitic and remain completely non-magnetic in annealed and cold-worked conditions.
SS 904L contains significantly higher levels of nickel (23–28%), molybdenum (4–5%), and added copper, making it far more resistant to pitting, crevice corrosion, and reducing acids than standard 316L.
As an experienced SS 904L Washers Supplier, Aurum Overseas manufactures washers according to ASME B18.21.1, DIN 125, DIN 127, DIN 9021, ISO 7089, and custom drawings.
Yes, the high 23–28% nickel content in SS 904L provides resistance to chloride-induced stress corrosion cracking.
Contact Aurum Overseas
Aurum Overseas stocks and manufactures high-performance SS 904L Washers for immediate global delivery.
Contact our technical sales team for instant quotes, MTR documentation, and custom sizing.