The specifications for manufacturing steel products are laid out in an EN steel standard. Generally speaking, EN standards must be followed if you operate in Europe, one of which is EN 10025.
What is EN 10025?
EN 10025 is a six-part European standard (or euro norm) for manufacturing hot-rolled structural steel products and their delivery conditions. Products applicable to EN 10025 are the hot-rolled steel coils and hot-rolled steel sections.
EN 10025 equivalent
Since the EU Standard categories are intrinsically not a universal standard, other countries of the world may use some similar grades with the same Chemical and Mechanical characteristics.
As an illustration, structural steels produced for the US market must be defined following ASTM International standards and will be referenced with an “A” (rather than “S” in EN standards) and the appropriate Grade. Below are examples in the table:
|
EN 10025 Equivalent US Grades |
|
|
Europe |
United States |
|
S235 |
A283C |
|
S275 |
A570Gr40 |
|
S355 |
A572Gr50 |
Classification
Following the European standard classifications, structural steels must be addressed using standard symbols such as but not limited to S, 235, J2/ K2/ JR/ JO, W, Z, and C.
- S – This means that it is structural steel.
- 235 – This relates to the steel’s minimum yield strength.
- JR/ J0/ J2/ K2 -These indicate the toughness of material in connection to “V” notch test method.
- W – This means it is weather resistant.
- Z – Thi indicates that the material is a reinforced structural steel parallel to the surface.
- C – This means the steel is cold-formed.
According to EN 10025, steel grades must be categorized as non-alloy quality steels. Steel grades S235 and S275 may be provided in JR, J0, and J2 qualities. S355 and S460 must follow JR, J0, J2, and K2 qualities while S500 may be offered with only J0 quality.
Specific impact energy requirements vary between the qualities, while there is none required for steel grades S185, and E295 to E360.
Manufacturing process
The manufacturing process includes steel-making and deoxidation. Except for the open hearth (Siemens-Martin) process, the manufacturer has complete control over the steel-making process.
On the other hand, deoxidation techniques are categorized as follows:
- Optional – The method is at the manufacturer’s discretion.
- FN – The rimming steel is not authorized.
- FF – The steel that has been destroyed contains enough nitrogen-binding components to bind the available nitrogen (a minimum of 0.020% total aluminum). When no additional nitrogen-binding substances are present, the standard recommendation is a minimum aluminum to nitrogen ratio of 2:1. The inspection document must include information about these additional elements, including their content (% mass).
Technological properties
General criteria for welding steel qualities JR, J0, J2, and K2 are specified in EN 1011-2 while recommendations for hot/ cold forming and flame straightening are described in CEN/TR 10347.
Technological properties indicated in EN 10025 are as follows:
- Products that are ordered and delivered in as-rolled or thermomechanical rolled states are not suitable for hot forming.
- Steel grades and qualities suitable for cold forming must be identified by the proper steel name and number.
- If indicated at the time of order, steels with a width of less than 150 mm and thickness of equal to or less than 30 mm, are suitable for flanging without cracking with the least advised bend radii.
- Production of steel sections by cold rolling can be done if the steel sheet is with a nominal thickness of less than 8 mm.
- With standard processes, any steel grades and qualities are machineable.
Surface properties
The surface properties vary depending on the type of structural steel:
- Strips. If the strip is processed properly, the surface condition should not prevent an application that is appropriate for the steel grade.
- Plates and wide flats. For the acceptable surface discontinuities and the surface defect rectification using grinding and/or welding, EN 10163-1 and EN 10163-2 shall apply.
- Bars and rods. Unless otherwise specified at the time of the order, Class A of EN ISO 9443 applies to the allowable surface discontinuities and the repair of surface flaws by grinding and/or welding.
Conclusion
The applications of structural steels are numerous and diverse. If steel manufacturers follow EN steel standards, then a good quality structural steel product will surely be produced.
