When selecting stainless steel for highly corrosive environments, both 316L and 904L are popular choices. But what sets them apart-and which one is right for your application? This article compares 904L and 316L stainless steels in terms of chemical composition, corrosion resistance, mechanical strength, cost, and common use cases.
| Element | 316L (UNS S31603) | 904L (UNS N08904) |
|---|---|---|
| Chromium (Cr) | 16.0–18.0% | 19.0–23.0% |
| Nickel (Ni) | 10.0–14.0% | 23.0–28.0% |
| Molybdenum (Mo) | 2.0–3.0% | 4.0–5.0% |
| Carbon (C) | ≤ 0.03% | ≤ 0.02% |
| Copper (Cu) | - | 1.0–2.0% |
Summary: 904L contains significantly higher levels of nickel and molybdenum than 316L, along with added copper, which greatly enhances its corrosion resistance in aggressive environments.
316L is highly resistant to general corrosion and pitting in chloride-rich environments. It performs well in marine settings and mild chemical processes.
904L, on the other hand, offers superior resistance to:
Sulfuric acid
Phosphoric acid
Chloride-induced pitting and crevice corrosion
Stress corrosion cracking (SCC)
Thanks to its high nickel and copper content, 904L is ideal for harsh chemical processing and acid handling.
| Property | 316L | 904L |
|---|---|---|
| Tensile Strength | ~485 MPa | ~490–710 MPa |
| Yield Strength | ~170 MPa | ~220 MPa |
| Elongation | ≥ 40% | ≥ 35% |
| Hardness (Brinell) | ≤ 217 HB | ≤ 220 HB |
Note: Both materials are austenitic and non-magnetic in the annealed condition, offering good weldability and formability.
Both 316L and 904L stainless steels are austenitic, meaning they cannot be hardened by heat treatment. Instead, their mechanical properties are primarily adjusted through cold working.
| Property | 316L | 904L |
|---|---|---|
| Heat Treatable? | Not hardenable by heat treatment | Not hardenable by heat treatment |
| Annealing Temperature | ~1,040–1,120 °C (1,900–2,050 °F) | ~1,090–1,170 °C (2,000–2,140 °F) |
| Cooling Method After Annealing | Rapid air or water quench | Rapid air or water quench |
| Intergranular Corrosion Resistance | Excellent due to low carbon | Excellent with proper annealing |
Due to its high alloy content, 904L is significantly more expensive than 316L-often by 2–3 times depending on market conditions. It's generally chosen only when 316L or even 317L is insufficient for the environmental demands.
Both grades are weldable using standard techniques (TIG, MIG), but 904L requires greater care due to its higher nickel content, which may lead to hot cracking if improperly managed.
316L is commonly used in:
Marine hardware
Heat exchangers
Food and pharmaceutical equipment
Architectural structures
904L is preferred in:
Chemical processing plants
Flue gas scrubbers
Acid storage tanks
Oil and gas offshore platforms
Pulp and paper industry (chloride-rich environments)
Need help choosing between 904L and 316L stainless steel for your project?
Contact our materials specialists for expert advice or request a free quote today.
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