SS904L
SS904L is a high-alloy, low-carbon austenitic stainless steel containing elevated nickel and molybdenum plus copper. It provides improved resistance to reducing acids and chloride-induced localized corrosion compared with standard 300-series grades.
SS904L Information
SS904L is a high-alloy, low-carbon austenitic stainless steel containing elevated nickel and molybdenum plus copper. It provides improved resistance to reducing acids and chloride-induced localized corrosion compared with standard 300-series grades.
Metallic winding and compatible ring components where service conditions are suitable.
| UNS Number | N08904 |
|---|---|
| EN / Werkstoff | 1.4539 |
| Material Type | High-Ni, high-Mo, Cu-bearing super-austenitic stainless steel |
| Common / Applicable Specification | ASTM A240 / A240M |
| Typical Gasket Use | Metallic winding and compatible ring components where service conditions are suitable. |
SS904L Chemical Composition
Reference composition limits are shown below. Exact requirements should be confirmed against the applicable product specification and certified material documentation.
| Element / Constituent | Symbol | Composition / Information |
|---|---|---|
| Carbon | C | 0.020 max. |
| Manganese | Mn | 2.00 max. |
| Silicon | Si | 1.00 max. |
| Phosphorus | P | 0.045 max. |
| Sulfur | S | 0.035 max. |
| Chromium | Cr | 19.0–23.0 |
| Nickel | Ni | 23.0–28.0 |
| Molybdenum | Mo | 4.0–5.0 |
| Copper | Cu | 1.0–2.0 |
| Iron | Fe | Balance |
SS904L Mechanical Properties
Reference room-temperature properties are shown for a commonly supplied condition. Exact requirements depend on product form, size, heat treatment and governing specification.
| Property | Reference Value | Unit / Basis |
|---|---|---|
| Tensile Strength | 490 min. | MPa |
| 0.2% Offset Yield Strength | 220 min. | MPa |
| Elongation | 35 min. | % |
Values shown are engineering reference data, not universal design allowables. Final procurement and design must use the governing specification, exact product form/condition and certified material test documentation.
SS904L Physical & Service Information
Reference physical properties and service considerations relevant to material selection for Spiral Wound Gaskets.
| Density | Approx. 8.0 g/cm³ |
|---|---|
| Structure | Austenitic |
| Corrosion Behaviour | Strong resistance to many reducing-acid environments and better chloride pitting resistance than 316L. |
| Heat Treatment | Normally solution annealed. |
| Service Selection | For very severe chlorides, compare with 6Mo or duplex/super-duplex grades. |
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