Stainless Steel 444 (UNS S44400)
Stainless Steel 444 is a low-carbon, low-nitrogen, ferritic stainless steel that provides excellent corrosion resistance in highly aggressive environments. Dual-stabilized with Titanium and Niobium, this alloy offers a unique combination of high resistance to pitting and crevice corrosion—comparable to Type 316—while remaining virtually immune to chloride-induced stress corrosion cracking (SCC). Because it is a ferritic grade, it also possesses superior thermal conductivity and a lower coefficient of thermal expansion compared to austenitic steels.
At Aries Alloys, we supply Stainless Steel 444 to industries dealing with hot water systems and chemical processing. It is the premier choice for applications where the high cost or SCC-vulnerability of the 300-series makes it unsuitable.
Key Performance Benefits
- SCC Immunity: As a ferritic stainless steel, it is nearly immune to chloride stress corrosion cracking, a common failure mode for Type 304 and 316 in hot, saline environments.
- Dual Stabilization: The combination of Titanium and Niobium prevents intergranular corrosion by "locking up" carbon and nitrogen, ensuring weld-zone integrity.
- High Pitting Resistance: Contains 18% Chromium and 2% Molybdenum, providing a level of protection against localized pitting that rivals Type 316.
- Thermal Efficiency: Higher thermal conductivity and lower thermal expansion than austenitic grades make it ideal for heat exchangers and boiler components.
- Magnetic Properties: Naturally magnetic, which can be a functional advantage in specific electronic and attachment applications.
Technical Profile & Composition
The Ferritic Advantage:
Unlike the 300-series, Type 444 has a ferritic microstructure. This provides better resistance to oxidation at high temperatures and ensures that the material does not become "sensitized" during welding, thanks to its extra-low carbon and nitrogen levels (C+N ≤ 0.025%).
Mechanical & Physical Data:
- Density: 7.75 g/cm^3
- Magnetic Property: Strongly magnetic.
- Oxidation Resistance: Excellent scaling resistance in continuous service up to 1650°F (900°C).
- Fabricability: Offers good ductility and can be formed into complex shapes, though it requires specialized welding techniques to maintain the refined grain structure.
Primary Industrial Use Cases
Aries Alloys provides Stainless Steel 444 for high-efficiency and high-durability infrastructure:
- Water Heating Systems: Hot water tanks, solar water heaters, and heat exchanger tubing where chloride levels are a concern.
- Food Processing: Equipment used in the brewing, dairy, and food industries where sanitation and corrosion resistance are key.
- Automotive Exhaust: Manifolds and muffler components that require high-heat durability and oxidation resistance.
- Chemical Industry: Storage tanks and process piping for mildly corrosive chemicals and organic acids.
- Architecture: Roofing and cladding in coastal environments where SCC is a risk for other grades.
Product Availability at Aries Alloys
We stock and supply Stainless Steel 444 in several formats complying with ASTM A240:
- Sheets & Plates: Precision-cut flat products for the fabrication of tanks and heat shields.
- Seamless & Welded Tubes: High-efficiency tubing for heat exchangers and hot water transport.
- Coils & Slit Strips: Custom-width strips for high-speed manufacturing and roll-forming.
- Custom Forgings: Flanges and fittings designed for high-integrity, corrosion-resistant connectivity.