What does JR stand for in S235JR?
S235JR is a non-alloy structural steel grade defined in the European standard EN10025. "S" stands for Structural Steel, "235" indicates the lower limit of the material's yield strength is 235 MPa, and "JR" represents the impact energy requirement at 0°C. As a general-purpose structural steel designated by the European Committee for Standardization (CEN), S235JR has wide applications in machinery manufacturing, construction engineering, and other fields.
From a material classification perspective, S235JR belongs to low-carbon carbon structural steel. Its chemical composition and mechanical properties are basically equivalent to the Q235B grade in the Chinese national standard GB/T700. This type of steel is characterized by a relatively low carbon content (typically between 0.05% and 0.70%), excellent weldability and formability, and is particularly suitable for the manufacture of various welded structures, bolted connections, and riveted structures.
Carbon structural steel can be divided into two main categories based on its quality grade: ordinary carbon structural steel and high-quality carbon structural steel. S235JR belongs to the category of ordinary carbon structural steel. Although its mechanical properties are not as stable as those of high-quality carbon structural steel, it has significant economic advantages in general structural applications that do not require high stress or impact loads due to its lower cost and good processing performance.
Standards and Certification Requirements
The production and quality control of S235JR steel strictly adhere to the EN10025 standard system. This standard specifies in detail the chemical composition, mechanical properties, dimensional tolerances, and surface quality of structural steel.
EN10025, as a commonly used European standard for structural steel, has been adopted by the International Organization for Standardization (ISO) as an international standard, ensuring the consistent quality of S235JR steel worldwide.
Production Process and Delivery Condition
Depending on customer needs and usage environment, S235JR steel can be delivered in two main heat treatment conditions: normalized and controlled rolling. Normalizing refines the grains and improves the uniformity of the material's mechanical properties; controlled rolling achieves an ideal microstructure by precisely controlling the rolling temperature and deformation.
Chemical Composition Table
| Element | S235JR (%) |
|---|---|
| Carbon (C) | ≤0.22 |
| Silicon (Si) | ≤0.55 |
| Manganese (Mn) | ≤1.50 |
| Phosphorus (P) | ≤0.035 |
| Sulfur (S) | ≤0.035 |
| Copper (Cu) | ≤0.55 |
| Nitrogen (N) | ≤0.012 |
Mechanical Properties Table
| Property | S235JR (MPa) |
|---|---|
| Yield Strength (Re) | ≥235 |
| Tensile Strength (Rm) | 360-510 |
| Elongation (A) | ≥18% |
Mechanical Performance Table
| Property | S235JR |
|---|---|
| Impact Toughness (KV) | ≥27J (0℃) |
| Hardness (HBW) | 120-170 |
| Cold Bending Performance | Passes bending test with d=2a |
S235JR square tube factory
