904l stainless steel VS.304L
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904l stainless steel VS.304L.pdf
What Is 904L Stainless Steel Equivalent To?
904L stainless steel is a high-alloy, low-carbon austenitic stainless steel known for its exceptional corrosion resistance, especially in aggressive and acidic environments.
| Standard | Equivalent Grade |
|---|---|
| UNS | N08904 |
| EN / DIN | 1.4539 / X1NiCrMoCu25-20-5 |
| ASTM | A240 / A312 / A276 / A479 |
| ISO | 904L |
| JIS | SUS 890L |
What Is the Equivalent of 304L Steel?
304L is a low-carbon version of 304 stainless steel, offering good corrosion resistance and excellent weldability.
| Standard | Equivalent Grade |
|---|---|
| UNS | S30403 |
| EN / DIN | 1.4307 / X2CrNi18-9 |
| ASTM | A240 / A312 / A182 |
| JIS | SUS 304L |
Compared to 904L, 304L is more cost-effective, but less resistant to aggressive corrosion, especially in high-chloride or reducing acid environments.
What Is the Difference Between SS304L and SS904?
| Property | 304L Stainless Steel | 904L Stainless Steel |
|---|---|---|
| Chromium Content | ~18% | ~19.5% |
| Nickel Content | ~8–10.5% | ~23–25% |
| Molybdenum | None | ~4.5% |
| Copper | None | ~1.5% |
| Carbon Content | ≤0.03% | ≤0.02% |
| Corrosion Resistance | Moderate | Excellent (especially in acids) |
| Resistance to Pitting (PREN) | ~18–20 | ~35–39 |
| Applications | Food, construction, piping | Chemical, pharmaceutical, marine |
| Cost | Low | High |
904L is far superior to 304L in resisting sulfuric acid, chloride pitting, and stress corrosion cracking.
304L is ideal for general-purpose, non-aggressive environments.
What Is the Corrosion Resistance of 904L Stainless Steel?
904L offers outstanding corrosion resistance, especially in the following areas:
✅ Strong Points:
Excellent resistance to sulfuric acid, phosphoric acid, and organic acids
Superior resistance to chloride-induced pitting and crevice corrosion
Effective against stress corrosion cracking in chloride-rich environments
✅ Typical Corrosive Environments Where 904L Performs:
Heat exchangers in chemical plants
Desalination equipment
Storage tanks for acids and chlorides
Pharmaceutical reactors
Marine applications exposed to salt spray
📈 PREN (Pitting Resistance Equivalent Number):
904L: ~35–39
304L: ~18–20
This difference highlights why 904L is chosen for high-end corrosion-critical components.
