Chemical composition and mechanical properties of S235J2
Here is a detailed breakdown of the chemical composition and mechanical properties of the structural steel grade S235J2, according to the European standard EN 10025-2:2004.
S235J2 is a non-alloy, carbon structural steel commonly used in construction and general engineering. The "J2" designation indicates it has specified impact toughness (Charpy V-notch) at -20°C, making it suitable for applications in cold environments.
1. Chemical Composition (by weight %)
The composition is key to the steel's weldability, toughness, and strength. Maximum values are specified.
| Element | Maximum % | Purpose/Effect |
|---|---|---|
| Carbon (C) | 0.17% max | Primary hardening element. Low carbon ensures good weldability and formability. |
| Manganese (Mn) | 1.40% max | Increases strength and hardenability, improves hot-working properties. |
| Phosphorus (P) | 0.035% max | Impurity. Harmful; reduces ductility and toughness (causes embrittlement). |
| Sulfur (S) | 0.035% max | Impurity. Harmful; reduces ductility and causes hot shortness during welding. |
| Silicon (Si) | ≤ 0.35% (typical) | Deoxidizing agent ("killed steel"). Contributes to strength. |
| Nitrogen (N) | 0.012% max | Can reduce ductility if not controlled; limited in J2 grade for toughness. |
Key Points on Composition:
It is a "mild steel" with low carbon content.
The Carbon Equivalent (CEV) for weldability is low, typically around 0.28-0.35%, calculated as:
CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15
This low value means it is excellent for welding without pre- or post-heating under normal conditions.
The J2 grade is fully "killed" (deoxidized), meaning it has a more uniform composition and structure than rimmed steels.
2. Mechanical Properties
Properties are specified for material up to 16 mm in thickness (the most common reference range). Properties decrease slightly with increasing thickness.
| Property | Value (for thickness ≤ 16mm) | Description / Test Standard |
|---|---|---|
| Yield Strength (ReH) | ≥ 235 MPa | The stress at which the material begins to deform plastically. This is the "235" in the name. |
| Tensile Strength (Rm) | 360 - 510 MPa | The maximum stress the material can withstand while being stretched. |
| Elongation at Break (A₅) | ≥ 26% (min) | A measure of ductility (% elongation on a gauge length of 5.65√S₀). |
| Impact Toughness (KV) | ≥ 27 J at -20°C | Charpy V-notch test. The "J2" grade guarantees this minimum energy absorption at -20°C. |
Important Note on Thickness:
Mechanical properties are thickness-dependent. For example:
For thickness >16 mm to 40 mm: Yield Strength decreases to ≥ 225 MPa.
For thickness >40 mm to 63 mm: Yield Strength decreases to ≥ 215 MPa.
3. Equivalent Grades
S235J2 is part of a European nomenclature. Here are its closest equivalents in other standards:
Summary of Key Characteristics
Strength: Moderate yield strength (235 MPa).
Toughness: Guaranteed good impact resistance down to -20°C.
Weldability: Excellent, due to low carbon content and low Carbon Equivalent.
Machinability: Good.
Formability: Very good, due to high ductility.
Always remember: For critical applications, the relevant EN 10025-2 standard or its national adoption (e.g., BS EN 10025-2) should be the final authority, and material certification (mill sheets) must be verified.
Full specification and details are available on request. The above information is provided for guidance purposes only. For specific design requirements please contact our technical sales staff.
