Difference between S275NL and S355NL steel plate - Knowledge

S275NL and S355NL are European standard (EN 10025-3) weldable, fine-grain structural steels, both normalized for excellent low-temperature toughness (27 Joules at -50°C), but S355NL offers higher strength (min. 355 MPa yield for thicker plates) compared to S275NL (min. 275 MPa yield), making S355NL better for heavy-duty structures like bridges and machinery, while S275NL is more economical for lighter loads, both ideal for cold environments.

Chemical Composition Differences

Element	Symbol	S275NL Min (%)	S275NL Max (%)	S355NL Min (%)	S355NL Max (%)
Carbon	C	-	0.16	-	0.18
Silicon	Si	-	0.40	-	0.50
Manganese	Mn	0.50	1.50	0.90	1.65
Nickel	Ni	-	0.30	-	0.50
Phosphorus	P	-	0.025	-	0.025
Sulfur	S	-	0.020	-	0.020
Chromium	Cr	-	0.30	-	0.30
Molybdenum	Mo	-	0.10	-	0.10
Vanadium	V	-	0.05	-	0.12
Nitrogen	N	-	0.015	-	0.015
Niobium	Nb	-	0.05	-	0.05
Titanium	Ti	-	0.05	-	0.05
Aluminum	Al	-	0.020	0.020	-
Copper	Cu	-	0.55	-	0.55
CEV	-	-	0.40	-	0.43

Mechanical Properties Comparison

Nominal Thickness (mm)	Yield Strength ReH Min (MPa) S275NL	Yield Strength ReH Min (MPa) S355NL	Tensile Strength Rm (MPa) S275NL	Tensile Strength Rm (MPa) S355NL	Elongation A Min (%) Both	Charpy KV Longitudinal Min (J) at -50°C Both
≤ 16	275	355	370–510	470–630	24	27
16 < t ≤ 40	265	345	370–510	470–630	24	27
40 < t ≤ 63	255	335	370–510	470–630	24	27
63 < t ≤ 80	245	325	370–510	470–630	23	27
80 < t ≤ 100	235	315	370–510	470–630	23	27
100 < t ≤ 150	225	295	350–480	450–600	23	27
150 < t ≤ 200	215	285	350–480	450–600	23	27
200 < t ≤ 250	205	275	350–480	450–600	23	27

Key Differences & Similarities

Strength: S355NL has higher minimum yield (355 MPa) and tensile strength (470-630 MPa) than S275NL (275 MPa yield, 370-510 MPa tensile), suiting heavier loads.

Temperature Performance: Both guarantee 27 Joules impact energy at -50°C (NL suffix), ideal for cold climates.

Composition: S355NL allows slightly higher carbon, silicon, manganese, and vanadium for increased strength, but both maintain low phosphorus/sulfur for toughness.

Applications: S355NL is for highly stressed parts (heavy machinery, bridges), while S275NL is for lighter-duty, cost-sensitive projects needing cold toughness.

Standards: Both fall under EN 10025-3 for normalized fine-grain steels, meaning they are processed for fine grain structure and toughness.

Applications and Selection Criteria
S275NL: Cost-effective for moderate loads in cold climates (e.g., standard bridges, cranes). See en 10025 3 s275nl normalized structural steel plate.
S355NL: Preferred for high-strength needs in demanding structures like offshore platforms, heavy-duty bridges, or wind turbine bases. See en 10025 3 s355nl normalized structural steel plate.