S235, S275, and S355 Structural Steel Comparison and Properties

Introducción

Structural steel grades S235, S275 y S355 are defined under the Norma EN 10025 y representan los materiales más utilizados en edificios, puentes, estructuras marítimas y maquinaria pesada.

This guide provides a practical comparison of S235 vs S275 vs S355, including yield strength, tensile strength, chemical composition, mechanical properties, and equivalents in ASTM, JIS, and GB standards. It focuses on technical performance rather than procurement or cost.

S235, S275, and S355 Structural Steels Grades Overview

Grado	Mínimo límite elástico (MPa)	Typical Suffix	Prueba de impacto
S235	235	JR	Room temperature
S275	275	JR	Room temperature
S355	355	JR / J2 / NL	Room / Low temperature

El sistema de designación de la norma EN 10025 es sencillo:

• La carta "S" significa acero estructural.
• El número representa el límite elástico mínimo en N/mm².
• Suffixes like JR, J2, NL indicate impact toughness requirements.

👉 For more details on suffixes like JR, J2, and NL, see our guide: S355JR / S355J2 / S355NL - ¿Cuál es la diferencia?

Mechanical Properties of S235, S275 and S355 Steel

Mechanical performance varies among S235/S275/S355 primarily in yield strength (ReH) and tensile strength (Rm). Yield strength is the primary classification basis under EN 10025, while tensile strength provides an additional reference for overall mechanical performance.

1. Yield Strength of S235, S275 and S355 (EN 10025)

According to EN 10025-2, the minimum yield strength (fy) of structural steel grades S235, S275, and S355 is defined as 235 MPa, 275 MPa, and 355 MPa respectively for plate thickness up to 16 mm. These values represent standard-specified minimums rather than guaranteed test results for every heat. As thickness increases, the minimum required yield strength decreases in stepwise ranges as specified in the standard.

This stepwise increase in fy explains the fundamental structural difference between S235, S275, and S355, with S355 preferred for heavy load-bearing or dynamically loaded structures, while S235 and S275 are more commonly used for light and medium structural applications.

2. Mechanical Properties Comparison of S235, S275 and S355 Steel

The table below compares the key mechanical properties of S235, S275, and S355 structural steel, including yield strength (ReH), tensile strength (Rm), elongation, impact resistance, weldability, and formability.

Propiedad	S235	S275	S355
Límite elástico (MPa)	235	275	355
Resistencia a la tracción (MPa)	360-510	370-530	470-630
Alargamiento (%)	≥26	≥23	≥22
Resistencia a los impactos	Básico	Mejorado	Excelente, apto para bajas temperaturas
Soldabilidad	Excelente	Excelente	Bien
Formabilidad	Alta	Moderado	Baja

Composición química de S235, S275 y S355 (comparación de C y Mn)

La diferencia en el límite elástico procede principalmente del contenido de carbono y manganeso.

Grado	Carbono (C %)	Manganeso (Mn %)	Explicación
S235	≤0.17	≤1.40	Bajo contenido en carbono, excelente soldabilidad, menor resistencia
S275	≤0.21	≤1.50	Carbono y manganeso ligeramente superiores, propiedades equilibradas
S355	≤0.24	≤1.60	Mayores niveles de C y Mn, lo que se traduce en un mayor límite elástico

Engineers should note that while increasing C and Mn enhances límite elástico, it can slightly reduce weldability.

S235, S275 y S355 Equivalentes materiales

Below is a simplified equivalence chart for S235, S275, and S355 steel:

Norma EN	Equivalente ASTM	Equivalente JIS	Equivalente GB
S235JR	ASTM A36	SS400	Q235B
S275JR	ASTM A36 / ASTM A529	SM400A / B	Q275
S355JR	ASTM A572	SM490A / B	Q345B

S235 vs S275 vs S355: Key Technical Differences

1.Strength: S355 > S275 > S235 in both yield and tensile strength

2.Structural Load Capacity:

• S235 → light structures
• S275 → medium-load components
• S355 → heavy-duty structures (bridges, cranes, machinery)

3.Weldability: All grades offer good weldability

4.Toughness / Sub-Grades: JR → J0 → J2, increasing energy absorption (Charpy impact)

Aplicaciones del acero estructural S235 / S275 / S355

Elegir entre S235, S275 y S355 depende tanto de los requisitos estructurales como del entorno del proyecto.

S235 - Para estructuras ligeras y fabricación general

• Frames, fences, containers, small workshops
• High weldability and formability

👉 Producto relacionado:

• S235JR Carbon Steel Coil
• S235JR Carbon Steel Plate
• S235 Welded Steel Pipe

S275 - Para estructuras de resistencia media

• Commercial buildings, bridges, industrial machinery bases
• Balanced strength, ductility, and price

S355 - Para cargas pesadas o dinámicas

• Bridges, offshore platforms, wind towers, high-rise structures
• Superior yield strength and impact toughness, especially at low temperatures

👉 Producto relacionado:

• S355JR Carbon Steel Plate
• S355JR Carbon Steel Coil
• Placa de acero para torre eólica S355J2 / S355JR

Cómo elegir entre los tipos de acero S235, S275 y S355

Tipo de proyecto	Grado recomendado	Razón
Estructura ligera, estructura de almacén	S235	Fácil fabricación, menor coste
Estructura comercial o puente	S275	Mayor capacidad de carga, coste moderado
Construcción en alta mar o en altura	S355	Alta resistencia, excelente tenacidad

Al comparar S275 frente a S355, consider environmental factors like wind, vibration, and temperature; S355 performs better in offshore or cold regions.

Preguntas frecuentes

• Q: What is the yield strength of S235 steel according to EN 10025?
  A: According to EN 10025-2, the minimum yield strength of S235 structural steel is 235 MPa for plate thickness up to 16 mm. For thicker plates, the specified minimum yield strength decreases stepwise depending on thickness ranges defined in the standard.
• Q: What is the yield strength of S275 steel in MPa?
  A: The minimum yield strength of S275 steel is 275 MPa for thickness up to 16 mm, as specified in EN 10025-2. For greater thicknesses, the minimum yield strength is reduced according to the standard’s thickness-dependent limits.
• Q: What is the tensile strength of S275 steel?
  A: S275 typically offers 370–530 MPa tensile strength, depending on thickness.
• Q: What are the chemical composition limits for these grades?
  A: The main variations involve carbon and manganese: S235 (lowest), S355 (highest), reflecting their strength differences.
• Q: What are the ASTM, JIS, and GB equivalents for S355?
  A: ASTM A572 Grade 50, JIS SM490, and GB Q345B.
• Q: What are the differences between S275 and S355?
  A: S355 has higher yield/tensile strength, better impact resistance, and is suitable for heavy-duty or cold-environment applications.
• Q: Are S235, S275, and S355 weldable?
  A: Yes. All three grades are weldable; S235 is generally easiest to fabricate.

Conclusión

A la hora de elegir entre S235 vs S275 vs S355La elección de la mejor calidad depende de los requisitos de resistencia del proyecto, del presupuesto y del plazo de entrega.

• S235 - Económico, fácil de fabricar.
• S275 - Equilibrio entre rendimiento y coste.
• S355 - Calidad superior para estructuras exigentes.

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