What is 1.4401 Stainless Steel?

1.4401 stainless steel, commonly known as 316 or UNS S31600, is a molybdenum-alloyed austenitic stainless steel. The addition of molybdenum significantly enhances its corrosion resistance, particularly against chlorides and industrial chemicals, making it the standard choice for more aggressive environments than 304 can handle, such as marine applications, chemical processing, and pharmaceutical equipment.

 

This molybdenum-enhanced grade is standardized across all major international systems.

Standard	Equivalent Grade
EN (Europe)	1.4401
ASTM/AISI (USA)	316, UNS S31600
JIS (Japan)	SUS316
KS (Korea)	STS316

Molybdenum (Mo) is the key alloying element that differentiates it from 304.

Element	C	Si	Mn	P	S	Cr	Ni	Mo
Content (%)	≤ 0.07	≤ 1.0	≤ 2.0	≤ 0.045	≤ 0.03	16.5 - 18.5	10.0 - 13.0	2.0 - 2.5

It offers good strength and excellent ductility.

Property	Yield Strength (Rp0.2)	Tensile Strength (Rm)	Elongation (A)	Hardness (HB)
Typical Value	≥ 205 MPa	500 - 700 MPa	≥ 40%	≤ 215

 

Key Characteristics and Applications of 1.4401 / 316

Superior Corrosion Resistance: The molybdenum content provides significantly better resistance to pitting and crevice corrosion in chloride-containing environments (e.g., seawater, de-icing salts) compared to 304.

Good Acid Resistance: Offers improved resistance to a wider range of acids, including sulfuric, phosphoric, and acetic acids.

Excellent Formability and Weldability: Maintains the good forming and welding characteristics of austenitic stainless steels.

 

Primary Applications:

Marine & Coastal: Boat fittings, underwater components, and architectural cladding in salt-laden atmospheres.

Chemical Processing: Tanks, pipes, valves, and pumps for handling corrosive chemicals.

Pharmaceutical & Food: Equipment requiring high cleanliness and resistance to sterilizing agents.

Medical Devices: Surgical instruments and implants (in specific conditions).

 

What is the primary advantage of 316 (1.4401) over 304 (1.4301) stainless steel?
The main advantage is the addition of 2-2.5% molybdenum, which dramatically improves resistance to localized corrosion-especially pitting and crevice corrosion-in environments containing chloride ions. This makes 316 the preferred choice for applications in marine environments, chemical processing plants using chlorides, and anywhere exposure to salt or halogen compounds is expected.

 

Can 316 stainless steel be used in seawater applications?
While 316 is significantly more resistant to chloride attack than 304, its performance in stagnant or slow-moving seawater can be limited, especially at higher temperatures or in crevice conditions. For fully immersed seawater applications, more highly alloyed stainless steels (like duplex 2205 or super duplex grades) or non-ferrous alloys are often recommended. 316 is suitable for above-waterline marine components and in splash zones with proper maintenance.

 

Looking for a Reliable Supplier of 1.4401 / 316 Stainless Steel?
GNEE Steel supplies premium 316 (1.4401) stainless steel in all standard forms-plate, sheet, coil, pipe, and bar-tailored for corrosive environments. We provide full material certification and comprehensive processing services. If you have any requirements, please feel free to contact us.

 

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