What is the difference between SUS316L and SUS316LN?

Comparison Between SUS316L and SUS316LN Stainless Steel (Based on JIS Standards)

 

SUS316L
A low-carbon austenitic stainless steel defined in Japanese JIS standards (e.g., JIS G4303). The suffix "L" indicates Low Carbon, with a carbon content ≤0.03%, which significantly reduces the risk of intergranular corrosion after welding.

SUS316LN
An enhanced version of SUS316L with the addition of nitrogen (N). The "LN" stands for Low Carbon + Nitrogen, typically containing 0.10–0.16% nitrogen. This alloy retains excellent corrosion resistance while offering higher mechanical strength. It is also standardized under JIS G4303.

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2.SUS316L and SUS316LN Stainless Steel ：Chemical Composition Comparison (Key Differences)

Element	SUS316L (JIS G4303)	SUS316LN (JIS G4303)
C (Carbon)	≤0.03%	≤0.03%
N (Nitrogen)	≤0.10% (typically <0.03%)	0.10–0.16%
Other Elements	Cr: 16–18%, Ni: 10–14%, Mo: 2.0–3.0%	Same as SUS316L

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3. SUS316L and SUS316LN Stainless Steel ：Mechanical Properties at Room Temperature (Annealed Condition)

Property	SUS316L	SUS316LN
Yield Strength (MPa)	≥205	≥245
Tensile Strength (MPa)	≥480	≥520
Elongation (%)	≥40	≥35
Hardness (HB)	≤217	≤220

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4. SUS316L and SUS316LN Stainless Steel ：Corrosion Resistance Comparison

Intergranular Corrosion:
Both are ultra-low carbon grades (C ≤ 0.03%) and show excellent resistance to intergranular corrosion. No post-weld heat treatment is required-an advantage over standard 316.

Pitting and Crevice Corrosion:
SUS316LN performs slightly better due to nitrogen-enhanced passive film stability, especially in chloride-containing environments such as seawater or brine.

Stress Corrosion Cracking (SCC):
While austenitic stainless steels are generally more resistant to SCC than ferritic/martensitic grades, SUS316LN's higher strength means stress control is more critical in corrosive environments.

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5.SUS316L and SUS316LN Stainless Steel ：Welding 

Machinability:
Both are austenitic stainless steels and offer good cold formability. SUS316LN tends to work harden faster due to nitrogen-tool wear and forming forces should be considered.

Welding Guidelines:

SUS316L: Use ER316L welding wire for matching low-carbon characteristics.

SUS316LN: Use nitrogen-bearing filler (e.g., ER316LN) to retain strength in the weld zone. Using ER316L may result in reduced weld strength.

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6.How to Choose Between SUS316L and SUS316LN

Aspect	SUS316L	SUS316LN
Nitrogen Content	Very low (≤0.10%)	0.10–0.16%
Strength	Moderate	~20% higher yield strength
Corrosion Resistance	Excellent	Slightly better pitting resistance
Application Suitability	Corrosion-focused, weld-friendly	High strength + corrosion resistance in pressure or structural use