What is 1.4404 Stainless Steel?

1.4404 stainless steel, commonly known as 316L or UNS S31603, is the low-carbon variant of the standard 316 molybdenum-alloyed austenitic stainless steel. Its reduced carbon content (≤0.03%) enhances resistance to intergranular corrosion in the as-welded condition, making it the preferred choice for heavy welded fabrications, chemical processing equipment, pharmaceutical devices, and marine applications where both corrosion resistance and weld integrity are critical. As one of the most versatile and widely used stainless steels, it offers an excellent balance of corrosion resistance, formability, and weldability.

 

This low-carbon molybdenum-enhanced grade is standardized under all major international systems.

Standard	Equivalent Grade
EN (Europe)	1.4404
ASTM/AISI (USA)	316L, UNS S31603
JIS (Japan)	SUS316L
KS (Korea)	STS316L
Common Name	316L

The low carbon content (≤0.03%) and molybdenum addition (2-3%) are key to its enhanced performance.

Element	C	Si	Mn	P	S	Cr	Ni	Mo
Content (%)	≤ 0.03	≤ 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, similar to standard 316.

Property	Yield Strength (Rp0.2)	Tensile Strength (Rm)	Elongation (A)	Hardness (HB)
Typical Value	≥ 200 MPa	490 - 690 MPa	≥ 40%	≤ 215

 

Key Characteristics and Applications of 1.4404 / 316L

Superior Weldability without Sensitization: The low carbon content (≤0.03%) minimizes chromium carbide formation during welding, preventing intergranular corrosion in the heat-affected zone without the need for post-weld heat treatment.

Enhanced Corrosion Resistance: The molybdenum addition (2-2.5%) provides significantly better resistance to pitting and crevice corrosion in chloride-containing environments compared to 304/304L.

Good Acid Resistance: Offers improved performance in sulfuric, phosphoric, and acetic acid environments, making it suitable for chemical processing applications.

Excellent Formability and Toughness: Maintains the good ductility and impact resistance characteristic of austenitic stainless steels, even at cryogenic temperatures.

 

Primary Applications:

Chemical & Pharmaceutical: Tanks, reactors, piping, and vessels for corrosive media requiring high purity.

Marine & Coastal: Boat fittings, offshore platforms, and components exposed to seawater or salt spray.

Medical & Food Processing: Surgical instruments, implants, and equipment requiring sterilization and high cleanliness.

Architectural: High-end façades, railings, and structures in polluted or coastal atmospheres.

Pulp & Paper: Process equipment in bleaching and chemical recovery areas.

Textile Industry: Equipment for dyeing and bleaching operations.

 

When should I choose 316L (1.4404) over 316 (1.4401)?
Choose 316L when the component will be heavily welded and cannot be post-weld heat treated, or when it will be used in the sensitization temperature range (450–850°C). This includes thick-section welds, multi-pass welds, or applications where the welded structure will be exposed to corrosive environments. 316L is also preferred for aggressive corrosive environments where maximum corrosion resistance is required, and for applications requiring approval from pressure vessel codes. For applications with minimal welding or where higher ambient strength at elevated temperatures is needed, standard 316 may be suitable and slightly more economical.

 

Does 316L have lower mechanical strength than 316 due to its lower carbon content?
In practice, the difference in room-temperature mechanical properties between annealed 316 and 316L is minimal and often within specification overlap. Both grades meet similar minimum strength requirements (200 MPa yield for 316L, 205 MPa for 316). The primary advantage of 316L is its corrosion resistance after welding or high-temperature exposure, not a reduction in ambient strength. At elevated temperatures (>500°C), 316 may have slightly higher creep strength due to its higher carbon content, which is why 316H (high-carbon) is specified for high-temperature service.

 

What are the welding considerations for 316L?
316L has excellent weldability using all common methods including TIG, MIG, SMAW, and SAW. Matching filler metals (ER316L for TIG/MIG, E316L-16 for SMAW) are recommended to maintain corrosion resistance. The low carbon content eliminates the need for post-weld heat treatment, even for thick sections. Recommended heat input is typically 0.5-2.0 kJ/mm, with interpass temperature below 150°C. Shielding gas (argon or argon with 2-5% nitrogen) protects the weld pool. Post-weld cleaning and pickling/passivation are recommended to restore the passive layer and ensure optimum corrosion resistance.

 

Looking for a Reliable Supplier of 1.4404 / 316L Stainless Steel?
GNEE Steel supplies high-quality 316L (1.4404) stainless steel in all standard forms-plate, sheet, coil, pipe, bar, wire, and fittings-along with comprehensive processing services such as cutting, bending, forming, and surface finishing. We provide full material certification (EN 10204 3.1) and ensure timely delivery for both stock and custom orders. If you have any requirements, please feel free to contact us.