EN 10025-2 is a European standard specifying technical delivery conditions for non-alloy structural steels, including S235JR, a widely used mild steel grade. Below is a concise overview of the quality standards for S235JR steel production under EN 10025-2, tailored for clarity and understanding.
Key Aspects of EN 10025-2 for S235JR Steel
Practical Implications
Scope and Classification:
EN 10025-2 covers non-alloy structural steels for general construction, with S235JR being a basic grade.
S235JR is designated by its minimum yield strength of 235 MPa (for thicknesses ≤ 16 mm) and "JR" indicating testing at room temperature (20°C) with a minimum impact energy of 27 Joules.
Chemical Composition:
S235JR has defined limits for chemical elements to ensure weldability and structural integrity.
Maximum content (based on ladle analysis, as per EN 10025-2):
Carbon (C): ≤ 0.17%
Manganese (Mn): ≤ 1.40%
Phosphorus (P): ≤ 0.035%
Sulfur (S): ≤ 0.035%
Nitrogen (N): ≤ 0.012% (if specified)
Copper (Cu): ≤ 0.55% (optional, for weather-resistant variants)
Exact composition varies slightly with thickness and product form (e.g., plates, sections).
Mechanical Properties:
Yield Strength: Minimum 235 MPa for thicknesses ≤ 16 mm; decreases for thicker sections (e.g., 225 MPa for 16–40 mm).
Tensile Strength: 360–510 MPa (varies by thickness).
Elongation: Minimum 26% for longitudinal specimens (for thicknesses ≤ 40 mm).
Impact Resistance: 27 J at 20°C (JR designation).
Production Requirements:
Manufacturing Process: S235JR is typically produced via basic oxygen steelmaking or electric arc furnace, followed by hot rolling.
Delivery Conditions: Supplied in as-rolled (AR), normalized (N), or normalized rolled (NR) conditions, with AR being common for S235JR.
Surface Quality: Must be free from defects like cracks, seams, or excessive scale, as per EN 10163 for plates and sections.
Tolerances: Dimensional tolerances comply with standards like EN 10029 (plates) or EN 10034 (sections).
Testing and Certification:
Mandatory Tests:
Chemical analysis (ladle or product).
Tensile testing for yield and tensile strength.
Impact testing at 20°C for JR grades.
Optional Tests: Can include ultrasonic testing, weldability tests, or through-thickness properties, if specified.
Certification: A test certificate (e.g., 2.2 or 3.1 as per EN 10204) is issued, confirming compliance with EN 10025-2.
Quality Classes:
S235JR can be supplied with additional quality designations (e.g., +AR, +N), affecting processing and properties.
Buyers specify options like deoxidation method (fully killed steel) or suitability for specific applications (e.g., cold forming).
Applications: S235JR is used in construction (bridges, buildings), machinery, and general structural components due to its balance of strength, ductility, and cost.
Weldability: Excellent, due to low carbon and sulfur content, but preheating may be needed for thicker sections.
Compliance: Manufacturers must ensure traceability, consistent quality, and adherence to EN 10025-2 through rigorous process controls.
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