European Steel Charpy Impact Values — EN 10025-2 JR/J0/J2/K2 Guide
Complete Charpy V-notch (CVN) impact energy requirements for European structural steels per EN 10025-2:2019. Covers JR, J0, J2, and K2 quality designations across S235, S275, S355, and S420/S460 grades. Minimum energy values, test temperatures, longitudinal versus transverse requirements, and grade selection guidance for fracture-critical applications.
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Charpy Quality Designation System
EN 10025-2 uses suffix letters to indicate Charpy impact testing requirements:
| Suffix | Test Temperature | Min CVN Energy (Longitudinal) | Typical Specification |
|---|---|---|---|
| JR | 20°C | 27 J | Interior members, warm environments |
| J0 | 0°C | 27 J | Exterior temperate climate, most European use |
| J2 | -20°C | 27 J | Cold climate, fracture-critical members |
| K2 | -20°C | 40 J | High toughness, offshore, seismic, wind towers |
The JR suffix is the most basic quality designation. J2 is the most commonly specified for primary structural members in Northern and Central Europe. K2 is required for fatigue-loaded structures and low-temperature applications per EN 1993-1-10.
Min CVN Energy by Grade and Quality
S235 Series
| Quality | Test Temp | Min Energy (J) Longitudinal | Min Energy (J) Transverse | Typical Use |
|---|---|---|---|---|
| S235JR | 20°C | 27 J | — | Secondary framing, interior |
| S235J0 | 0°C | 27 J | — | Exterior light framing |
| S235J2 | -20°C | 27 J | — | Primary members, cold climate |
Note: For S235 grades, transverse Charpy testing is not typically required. The JR quality is adequate for most non-structural applications.
S275 Series
| Quality | Test Temp | Min Energy (J) Longitudinal | Min Energy (J) Transverse | Typical Use |
|---|---|---|---|---|
| S275JR | 20°C | 27 J | — | General structural, warm interior |
| S275J0 | 0°C | 27 J | — | Exterior building frames |
| S275J2 | -20°C | 27 J | — | Primary structural, cold climate |
S355 Series
| Quality | Test Temp | Min Energy (J) Longitudinal | Min Energy (J) Transverse | Typical Use |
|---|---|---|---|---|
| S355JR | 20°C | 27 J | — | Warm interior, low-risk |
| S355J0 | 0°C | 27 J | — | Exterior frames, temperate |
| S355J2 | -20°C | 27 J | 27 J | Standard for primary members |
| S355K2 | -20°C | 40 J | 27 J | High toughness, fatigue, offshore |
Important: S355J2 and S355K2 require transverse Charpy testing. The transverse requirement is often the governing criterion for plates over 25 mm thickness.
S420 and S460 Series
| Quality | Test Temp | Min Energy (J) Longitudinal | Min Energy (J) Transverse | Typical Use |
|---|---|---|---|---|
| S420J2 | -20°C | 27 J | 27 J | High-strength, cold climate |
| S460J2 | -20°C | 27 J | 27 J | High-strength primary members |
| S460K2 | -20°C | 40 J | 27 J | High-strength, offshore, wind |
S420 and S460 to EN 10025-3 (normalized) or EN 10025-4 (thermomechanical rolled) are fine-grain structural steels offering improved Charpy properties.
Charpy Selection per EN 1993-1-10
EN 1993-1-10 provides thickness-dependent material toughness selection based on:
- Minimum service temperature (T_ed)
- Stress level (general stress vs. welded detail stress)
- Element thickness
- Steel grade and quality
The standard provides a table relating steel grade, quality, thickness, and minimum service temperature. For example:
| Grade/Quality | Max Thickness at -20°C (General) | Max Thickness at -30°C (General) |
|---|---|---|
| S235J2 | 120 mm | 80 mm |
| S275J2 | 100 mm | 60 mm |
| S355J2 | 70 mm | 40 mm |
| S355K2 | 100 mm | 70 mm |
| S460J2 | 60 mm | 30 mm |
For welded details, the allowable thickness reduces by approximately 30-50% depending on the detail category per EN 1993-1-10 Annex C.
Practical Design Guidance
When to Specify Each Quality
- JR — Members entirely inside heated buildings where minimum temperature is above 15°C. Secondary bracing, purlins, girts, handrails.
- J0 — Exterior members in Southern Europe (Mediterranean climate). Canopies, mezzanine frames, platform structures.
- J2 — Standard for all primary structural members in Central and Northern Europe. Building frames, bridges in temperate regions, crane runway beams.
- K2 — Offshore platforms, wind turbine towers, bridge tension members in cold regions, seismic energy dissipation elements, LNG facilities.
Plate Direction Considerations
For plates over 25 mm in thickness subject to through-thickness tension (restrained welds, T-joints), consider specifying Z-quality per EN 10164 for lamellar tearing resistance. Z-quality is independent of Charpy quality and is denoted as Z15, Z25, or Z35.
Frequently Asked Questions
What is the difference between J2 and K2 Charpy requirements?
J2 requires a minimum of 27 J at -20°C in both longitudinal and transverse directions. K2 requires a minimum of 40 J (longitudinal) and 27 J (transverse) at -20°C. K2 provides approximately 50% higher impact energy absorption and is specified for offshore, wind turbine, and seismic applications where higher fracture toughness is needed.
What Charpy quality should I specify for a steel building in London?
For a steel building in London (minimum outdoor temperature approximately -5°C to -10°C), specify S355J2 as the minimum quality for all primary structural members. J2 provides 27 J at -20°C, giving adequate margin above the design minimum temperature. For heavily loaded tension members or welded connections in plates over 25 mm, consider S355K2 or S460K2.
Is Charpy testing required for bolts per Eurocode 3?
Yes. EN 1993-1-8 requires bolts to meet Charpy impact requirements per EN 1993-1-10. Property class 8.8 and 10.9 bolts typically meet 27 J at -20°C (J2 equivalent) as standard. For temperatures below -20°C, consult EN 1993-1-10 Annex C for bolt grade selection.
Related Pages
- European Steel Grades — Full EN 10025-2 grade property guide
- European Steel Properties — Yield and tensile strength tables
- European Beam Sizes — IPE, HEA, HEB, HEM dimensions
- All European References
Educational reference only. Charpy impact values per EN 10025-2:2019. Thickness-temperature limits per EN 1993-1-10:2005. Verify material toughness against mill certificates and project specification requirements. For fracture-critical applications, consult EN 1993-1-10 Annex C for detailed acceptance criteria. Results are PRELIMINARY — NOT FOR CONSTRUCTION without independent verification.
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