1. Introduction to S235JRH
S235JRH is a non-alloy quality structural steel grade defined under the European standard EN 10210-1. The "H" at the end indicates that it is supplied in the Hot-finished condition.
This grade is characterized by good weldability and formability, along with guaranteed minimum impact energy (toughness) at room temperature. It is one of the most common grades used for general structural purposes like buildings, bridges, and mechanical frames.
Decoding the Grade Name: S235JRH
S: Structural Steel
235: Minimum specified Yield Strength (ReH) of 235 MPa (for thicknesses ≤ 16 mm).
J: Indicates a minimum Charpy V-Notch impact energy of 27 Joules.
R: The impact test is conducted at Room temperature (+20 °C).
H: Product form is Hot-finished.
2. Product Standards & Forms
S235JRH steel pipes are manufactured according to:
EN 10210-1: Hot finished structural hollow sections - Technical delivery conditions.
EN 10210-2: Hot finished structural hollow sections - Tolerances, dimensions, and sectional properties.
The standard covers seamless and hot-finished welded structural hollow sections (SHS – Square Hollow Sections, RHS – Rectangular Hollow Sections, and CHS – Circular Hollow Sections).
3. Chemical Composition (By Product Analysis)
The following table shows the maximum permissible percentages of chemical elements by weight, as specified in EN 10210-1.
Table 1: Chemical Composition (EN 10210-1)
| Element | Maximum % (for thickness ≤ 40 mm) | Maximum % (for thickness > 40 mm to 100 mm) |
|---|---|---|
| Carbon (C) | 0.20 | 0.22 |
| Silicon (Si) | 0.55 | 0.55 |
| Manganese (Mn) | 1.50 | 1.60 |
| Phosphorus (P) | 0.035 | 0.035 |
| Sulfur (S) | 0.035 | 0.035 |
| Nitrogen (N) | 0.015 | 0.015 |
*Note: The Cu content is typically ≤ 0.55%. The ratio of Mn/C must be ≥ 3.0 for improved weldability.*
4. Mechanical Properties
The key mechanical properties are guaranteed minimum values. The yield strength decreases as the material thickness increases.
Table 2: Mechanical Properties (EN 10210-1)
| Thickness (t) [mm] | Yield Strength (ReH) min. [MPa] | Tensile Strength (Rm) [MPa] | Elongation (A) min. [%] | Impact Energy (Kv) min. [J] |
|---|---|---|---|---|
| t ≤ 16 | 235 | 360 - 510 | 26 | 27 J @ +20°C |
| 16 < t ≤ 40 | 225 | 350 - 500 | 25 | 27 J @ +20°C |
| 40 < t ≤ 63 | 215 | 340 - 490 | 24 | 27 J @ +20°C |
| 63 < t ≤ 80 | 215 | 340 - 490 | 23 | 27 J @ +20°C |
| 80 < t ≤ 100 | 205 | 330 - 470 | 22 | 27 J @ +20°C |
ReH: Upper Yield Strength
Rm: Tensile Strength
A: Elongation on a gauge length of Lo=5.65√So
5. Key Characteristics & Applications
Weldability: Excellent. Can be welded by all conventional methods without pre-heating under most conditions (pre-heating may be required for very thick sections or in cold environments).
Machinability: Good.
Formability: Good for cold bending and other forming operations.
Impact Toughness: Guaranteed 27 Joules at room temperature, making it suitable for applications where minor dynamic loads are expected.
Typical Applications:
Building frames and structures
Bridges
Machinery and equipment frames
Agricultural structures
General construction and architectural applications
6. Equivalent Grades in Other Standards
S235JRH is approximately equivalent to grades in other international standards. However, direct equivalence is not always perfect due to slight differences in chemical composition or testing requirements.
| Standard | Equivalent Grade | Note |
|---|---|---|
| ISO 630 | Fe360B | Similar strength, but impact requirements may differ. |
| ASTM A36 | A36 | A36 is a carbon structural steel plate/shape grade, not a hollow section grade. The mechanical properties are similar. |
| JIS G3101 | SS400 | Similar strength, but SS400 specifies tensile strength only, not yield strength. |
Summary
S235JRH is a versatile, cost-effective, and widely available structural steel grade for hot-finished hollow sections. Its combination of adequate strength, good weldability, and guaranteed room-temperature toughness makes it a fundamental choice for a vast range of structural applications across Europe and other markets that adopt European standards.
