European quality specifications

At one time quality specifications for steel in many European countries varied significantly, leading to misunderstandings. Against that background, national quality specifications were replaced by a single system of European quality specifications. European standard EN 10025 describes the technical delivery conditions for hot rolled products of structural steels. This standard was produced to prevent confusion on steel grades and steel products.

Various symbols using letters and/or figures are used in addition to standard EN 10025 to further specify the Grade and properties of structural steel.

For instance, steel plate categorised as EN 10025 S235J2+N implies that the steel:

• EN 10025: complies with the European standard
• S235: the letter S is the basic symbol for structural steel, followed by a number indicating the specified minimum melting point expressed in MPa or N/mm2, for thicknesses equal to or less than 16 mm. In this case, the minimum melting point is 235 N/mm2 or 235 MPa.
• J2+N: is the grade specification, which consists of two letters or a combination of a letter and a number (JR, J0, J2, K2) and is an expression of weldability (weldability increases from grade JR to K2) and the minimum notch test reading as shown in the table below.

The notch test reading gives an indication of the relative ductility or brittleness of steel. The reading shows how much energy is absorbed by a tested bar of the material in question at a specific temperature before fracture. In this case the steel gives a guaranteed notch test reading of 27J at -20ºC (J2).

Where applicable, the specification may be followed by:

• + N, if the products must be delivered in normalised or equivalent condition. In this case the steel must be delivered in normalised (N) condition.
• + C: suitability for specific use, such as cold-drawing, profiling and cold flanging.
• + AR: “as rolled”.