S355JR
1.0045
Hot-rolled non-alloy structural steel · EN 10025-2:2019 — technical delivery conditions for hot-rolled non-alloy structural steels · EN 10025-1 — general requirements applicable when invoked for construction products
S355JR is the room-temperature-toughness quality of the EN 10025-2 S355 non-alloy structural steel family. It combines a minimum yield strength of 355 MPa at nominal thickness up to 16 mm with a specified Charpy V-notch energy of 27 J at +20 °C. Strength, carbon equivalent and some testing provisions depend on thickness and product form, while the JR impact test is performed only when requested at the time of order. It is a general structural grade rather than a low-temperature, pressure-purpose or inherently cold-forming grade.
- 1.0045Steel number · The numerical designation for S355JR under EN 10027-2.
- 355 MPa at t ≤ 16 mmMinimum yield strength · The minimum decreases progressively with increasing nominal thickness.
- 27 J minimum at +20 °CToughness class · Charpy V-notch, longitudinal test pieces; routine verification of JR impact properties must be ordered.
- Flat products to 400 mm; most long products to 250 mmProduct-standard scope · EN 10025-2 does not cover structural hollow sections or tubes.
- 0.45% to 0.49%Maximum CEV · Standard heat-analysis limits for S355JR depend on thickness; actual certificate chemistry should be used for welding assessment.
- +AR, +N or +M as applicableDelivery condition · +M is permitted for long products and strip, but not for quarto plate.
Overview
- Designation system
- EN steel name according to EN 10027-1; numerical designation according to EN 10027-2
- Product forms
- Plate, sheet and hot-rolled strip, Wide flats and flats, Hot-rolled structural sections, Bars and rod, Semi-finished products intended for further processing into covered flat or long products
- Condition
- +AR — as rolled, +N — normalized or normalized rolled, +M — thermomechanically rolled; available for long products and hot-rolled strip, not quarto plate
- Density
- 7850 kg/m³ (Volumetric mass used by EN 10025-2 for calculating nominal mass; it is not a heat-specific measured density.)
What the designation means—and what it does not mean
| Component | Meaning | Practical consequence |
|---|---|---|
| S | Structural steel | The designation is based primarily on mechanical performance rather than a narrowly fixed alloy recipe. |
| 355 | Minimum specified upper yield strength for nominal thickness ≤ 16 mm, in MPa | 355 MPa must not be applied automatically to thicker material. |
| JR | Minimum Charpy V-notch impact energy of 27 J at +20 °C | JR provides only a room-temperature impact class; it is not a guarantee of toughness at 0 °C or below. |
| 1.0045 | European steel number | An alternative identifier for the same standardized material. |
EN 10025-2 covers hot-rolled flat and long products. For S355JR, the standard applies to flat products through 400 mm and generally to long products through 250 mm. Hollow structural sections and tubes are outside its scope; products described as S355JR plate or section must not be assumed to establish compliance for a hollow-section product governed by EN 10210-1 or EN 10219-1.
Chemical composition and weldability control
| Item | EN 10025-2 requirement | Qualification |
|---|---|---|
| Deoxidation | FN | Rimming steel is not permitted. |
| C | ≤ 0.24% | Applies across the listed thickness ranges for S355JR. |
| Si | ≤ 0.55% | Silicon may need separate control when coating response during hot-dip galvanizing matters. |
| Mn | ≤ 1.60% | Maximum, not a target composition. |
| P | ≤ 0.035% | For long products, the permitted maximum may be 0.005% higher. |
| S | ≤ 0.035% | For long products, the permitted maximum may be 0.005% higher; a separately agreed machinability option can permit additional sulfur under controlled conditions. |
| N | ≤ 0.012% | The limit does not apply when sufficient aluminium or other nitrogen-binding elements are present and reported. |
| Cu | ≤ 0.55% | A controlled copper-alloyed option may be agreed separately. |
| Other elements | Not routinely specified as individual grade limits | Intentionally added elements must be reported; EN 10020 limits also constrain unspecified elements. |
These are heat-analysis requirements. Product-analysis limits are different and product analysis is carried out only when specified at ordering.
| Nominal product thickness (CEV) | t ≤ 30 mm | 30 < t ≤ 40 mm | 40 < t ≤ 150 mm | 150 < t ≤ 250 mm | 250 < t ≤ 400 mm |
|---|---|---|---|---|---|
| Maximum carbon equivalent based on heat analysis | 0.45% | 0.47% | 0.47% | 0.49% | 0.49% |
The 250–400 mm range applies to flat products. For long products in the 150–250 mm range, a maximum CEV of 0.54% may apply. Agreed copper-alloying or silicon control for galvanizing can increase the permitted CEV.
Mechanical requirements are thickness-dependent
| Nominal thickness t | Minimum ReH |
|---|---|
| t ≤ 16 mm | 355 MPa |
| 16 < t ≤ 40 mm | 345 MPa |
| 40 < t ≤ 63 mm | 335 MPa |
| 63 < t ≤ 80 mm | 325 MPa |
| 80 < t ≤ 100 mm | 315 MPa |
| 100 < t ≤ 150 mm | 295 MPa |
| 150 < t ≤ 200 mm | 285 MPa |
| 200 < t ≤ 250 mm | 275 MPa |
| 250 < t ≤ 400 mm | 265 MPa |
The 250–400 mm range applies to flat products. If no yield phenomenon occurs, the 0.2% proof strength is determined.
| Nominal thickness t | Specified Rm |
|---|---|
| t < 3 mm | 510–680 MPa |
| 3 ≤ t ≤ 100 mm | 470–630 MPa |
| 100 < t ≤ 150 mm | 450–600 MPa |
| 150 < t ≤ 250 mm | 450–600 MPa |
| 250 < t ≤ 400 mm | 450–600 MPa |
The 250–400 mm range applies to flat products.
| Nominal thickness t | Longitudinal | Transverse |
|---|---|---|
| 3 ≤ t ≤ 40 mm | 22% | 20% |
| 40 < t ≤ 63 mm | 21% | 19% |
| 63 < t ≤ 100 mm | 20% | 18% |
| 100 < t ≤ 150 mm | 18% | 18% |
| 150 < t ≤ 250 mm | 17% | 17% |
| 250 < t ≤ 400 mm | 17% | 17% |
For plate, strip and wide flats at least 600 mm wide, the transverse requirement applies. For other products, the longitudinal requirement applies. Different elongation requirements and an 80 mm gauge length apply below 3 mm.
The delivery condition does not change the tabulated grade requirements, but it can materially affect processing response and should still be identified on the inspection document and purchase order.
Impact toughness: the important JR limitation
| Test-piece orientation | Test temperature | Minimum average KV2 | Applicable thickness |
|---|---|---|---|
| Longitudinal | +20 °C | 27 J | Up to 400 mm within the product-form limits |
Reduced-width specimens use proportionally reduced energy requirements. Impact testing is generally not required where product dimensions cannot provide the prescribed specimen, including flat products and sections below 6 mm.
The JR suffix defines an impact-energy requirement, but EN 10025-2 does not automatically require routine verification of JR impact properties. Verification must be specified as an ordering option. This distinction matters when project documentation requires actual Charpy results on the inspection certificate rather than grade designation alone.
S355JR should not be selected merely because the minimum service temperature appears close to +20 °C. Brittle-fracture assessment also depends on design stress, detail category, thickness, strain rate, fabrication, residual stress and applicable design rules. Where lower-temperature toughness is needed, assess S355J0, S355J2 or S355K2 rather than treating JR as interchangeable.
Delivery condition, heat treatment and forming
| Condition | Process description | Availability and consequence |
|---|---|---|
| +AR | Conventional hot rolling without normalized rolling, thermomechanical rolling or subsequent normalizing | Permitted for long products, strip and quarto plate. |
| +N | Normalized rolled or normalized | Permitted for the covered forms; the preferred condition when subsequent normalizing or qualifying hot forming is intended. |
| +M | Thermomechanical rolling | Permitted for long products and hot-rolled strip, but not for quarto plate. +M material is not intended for subsequent hot forming. |
Unless a condition is ordered, the manufacturer may select among the conditions allowed for the product form.
S355JR is not generally intended for heat treatment after delivery. Products supplied in +N may be normalized or hot formed under the provisions referenced by the standard. Incorrect high-temperature processing, including uncontrolled flame straightening or rerolling, can reduce mechanical strength. Stress relieving above 580 °C or for more than one hour may impair properties; for normalized or normalized-rolled flat products, the standard recommends a maximum stress-relief temperature of 560 °C unless post-treatment properties are agreed at ordering.
The base designation S355JR does not by itself guarantee suitability for cold flanging or cold roll forming. Cold-forming capability must be specified through the applicable grade variant and ordering option. Notably, S355JRC is listed for cold drawing of bars, but not for the flanging or roll-forming guarantees available with S355J0C and S355J2C. Cold work also reduces ductility and can increase brittle-fracture sensitivity.
Fabrication implications
S355JR is intended to be arc welded using the recommendations of EN 1011-2, but the grade name is not a no-preheat guarantee. Hydrogen cracking risk increases with thickness, actual CEV, joint restraint, weld-metal hydrogen and heat-affected-zone hardness. Welding procedures should therefore be based on the certified heat chemistry, combined thickness and restraint conditions. The upper grade CEV limits are relatively high enough that thick or highly restrained work may need preheat and controlled heat input.
Ordinary S355JR chemistry permits a wide silicon range and therefore does not guarantee a particular zinc-coating appearance or growth rate. If coating control is important, the EN 10025-2 galvanizing-composition option should be agreed with the steelmaker, including the relevant silicon and phosphorus category. Coating requirements themselves should be specified separately under EN ISO 1461.
The grade can be machined using conventional operations. Its ductility may produce long chips and less consistent surface finish than free-machining steel. Higher-sulfur and calcium-treated long-product options can improve machinability, but alter the ordered chemistry and must not be assumed from the basic S355JR designation.
The standard tensile properties describe loading in the product plane; they do not establish resistance to lamellar tearing. Welded details imposing significant through-thickness strain may require an EN 10164 Z-quality and, where appropriate, ultrasonic examination ordered as additional requirements.
Specifying and purchasing S355JR
| Order item | Why it matters |
|---|---|
| Complete designation and standard edition | Use EN 10025-2:2019 S355JR together with any required condition suffix. |
| Product form and dimensional standard | EN 10025-2 is a delivery standard; dimensions, shape and tolerances come from the applicable plate, strip, section or bar standard. |
| Nominal dimensions and tolerances | Strength and CEV limits depend on nominal thickness. Hot-rolled plate otherwise defaults to EN 10029 thickness-tolerance class A. |
| Delivery condition | Specify +AR, +N or +M when processing or project requirements make the condition important. |
| Inspection document | State the required EN 10204 document, commonly type 3.1 where project traceability and test results are required. |
| JR impact verification | Order this specifically when actual Charpy test results are required. |
| Product analysis | Heat analysis is standard; product analysis requires a separate ordering option. |
| Galvanizing chemistry | Specify the required silicon/phosphorus category when predictable coating behavior matters. |
| Internal soundness or Z-quality | Ultrasonic testing and EN 10164 through-thickness properties are optional and must be ordered. |
| Surface quality | Default surface classes differ for plate, section and bar; tighter requirements must be stated. |
| Cold-forming guarantee | Do not infer flangeability or roll-forming suitability from S355JR alone. |
Certificate review should confirm the cast identity, product and thickness, full designation, delivery condition, actual heat analysis and CEV, tensile results in the applicable thickness range, and any specifically ordered impact, ultrasonic, Z-quality, galvanizing or forming requirements.
Substitution boundaries
A shared nominal yield strength does not establish equivalence. Substitution must consider the governing product standard, product form, thickness-dependent strength, toughness class and test temperature, delivery condition, chemical and CEV limits, dimensional tolerances, inspection certification and any project-specific testing. In particular, S355JR plate or section is not automatically interchangeable with an S355 hollow-section grade, a normalized fine-grain S355 grade under EN 10025-3, or an ASTM grade with a similar minimum yield strength.
Sources
- EN 10025-2:2019 — Hot rolled products of structural steels, Part 2: Technical delivery conditions for non-alloy structural steelsNEN
- EN 10025-2:2019 standard previewCEN / SIST via iTeh Standards
- BS EN 10025 — Hot rolled products of structural steelsBSI
- BS EN 10025-2:2019 — Hot Rolled Structural Steels StandardStudyLib reproduction of BSI/CEN document
- Steel material properties for structural design and performanceSteelConstruction.info
- Guidance Note 3.01 — Material selection and toughnessSteelConstruction.info
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