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Superalloy 904L (UNS N08904) Corrosion-Resistant Steel Sheet
904L is a high-performance austenitic stainless steel alloy with exceptional corrosion resistance, particularly in aggressive environments containing sulfuric acid, phosphoric acid, and chloride ions. Key features include:
- Superior Corrosion Resistance: Resists pitting, crevice corrosion, and stress corrosion cracking due to its high nickel (23–28%) and molybdenum (4–5%) content.
- Excellent Weldability: Low carbon content (≤0.02%) minimizes carbide precipitation, ensuring weld integrity.
- High Strength & Ductility: Retains mechanical properties at elevated temperatures (up to 400°C).
Chemical Composition (wt%)
Element | Content (%) | Role |
C | ≤0.02 | Reduces carbide formation, enhances weldability. |
Si | ≤1.00 | Improves oxidation resistance. |
Mn | ≤2.00 | Stabilizes austenitic structure. |
P | ≤0.045 | Minimizes brittleness. |
S | ≤0.035 | Prevents hot cracking. |
Cr | 19.0–23.0 | Enhances corrosion resistance. |
Ni | 23.0–28.0 | Maintains toughness and ductility. |
Mo | 4.0–5.0 | Resists localized corrosion. |
Cu | 1.0–2.0 | Improves acid resistance. |
I. Core Performance Characteristics
1. Excellent Corrosion Resistance
(1) Excellent performance in reducing acids such as dilute sulfuric acid (concentration 0-98%), acetic acid, formic acid, etc., and is widely applicable in sulfuric acid environments below 70°C
(2) High nickel-molybdenum content (24% Ni + 4.3% Mo) imparts resistance to chloride ion pitting, crevice corrosion, and stress corrosion cracking
(3) Low carbon design (≤0.02%) avoids intergranular corrosion after welding and is suitable for pressure vessel manufacturing
2. Mechanical and Physical Properties
(1) Tensile strength ≥520MPa, elongation ≥35%, density 8.0g/cm³
(2) Melting point 1300-13 90℃, good high temperature stability
3. Processing characteristics
(1) Supports manual arc welding and argon arc welding, and the supporting welding materials are E385 series
(2) Hot processing temperature is 900-1180℃, and the cooling rate needs to be controlled
II. Typical application areas
1. Petrochemical
Reactors, heat exchangers and sulfuric acid storage and transportation equipment, resistant to acidic medium corrosion
2. Environmental protection energy
Absorption towers and spray devices of power plant flue gas desulfurization systems, resistant to chloride ion corrosion
3. Marine engineering
Seawater desalination equipment, marine platform components, resistant to seawater pitting corrosion
4. Pharmaceuticals and food
Organic acid treatment equipment, meeting sanitary corrosion resistance requirements
Surface Treatment
- Polished Finish: Ra ≤0.8μm for hygienic applications (e.g., food processing).
- Passivation: Nitric acid treatment to enhance corrosion resistance.
Why Choose Us ?
- Certified Quality: Compliance with ASTM A240/ASME SA-240 and ISO 9328.
- Custom Sizing: Thickness 0.5–100mm, width up to 3000mm.
- Global Logistics: ISO-certified packaging with moisture-proofing.
Applications & Industries
Aerospace:
High-power density actuators.
Electronics:
Precision sensors & MEMS components.
Energy:
Magnetic coupling devices for turbines.
Frequently Asked Questions
Q1: Can 904L be used in seawater?
A: Yes, its high Mo content resists chloride-induced corrosion.
Q2: What is the maximum service temperature?
A: Continuous use up to 400°C (intermittent 450°C).
Q3: How does 904L compare to 316L in corrosion resistance?
A: 904L outperforms 316L in chloride environments (e.g., seawater) and sulfuric acid due to higher Ni/Mo/Cu content.
Q4: Can 904L be used in food contact?
A: Yes, certified for food/medical use due to non-reactive and non-toxic properties.
Q5: What precautions are needed during welding?
A: Use low heat input and post-weld annealing to maintain corrosion resistance.
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