Steel grade S235JR

S235JR steel is one of the most popular grades used in various industries. To determine its application, it is first necessary to decipher the designation. The first letter "S" according to the European standard stands for steel intended for structures, the number 235 is the minimum yield strength given in MPa for the smallest range of product thickness t ≤ 16 mm, and the letters at the end inform about additional properties of this steel grade, in this case JR stands for cracking resistance at 20℃ .

S235JR steel chemical composition

A very important factor in determining the mechanical properties of a given steel is its chemical composition. According to melt analysis, the chemical composition of S235JR steel should be in accordance with the values given in the table below.

Steel grade S235JR is one of the general-purpose structural steels that are most often used to manufacture sheets, bars or various sections. It is equivalent to the former very popular St3 steel, but with the development of manufacturing technology and the need to apply European metallurgical standards and guidelines for steel purity, today's steel called S235JR differs significantly in terms of quality. Currently produced steel has a much more homogeneous structure and chemical composition, especially due to the effective elimination of undesirable and harmful impurities with phosphorus and sulfur compounds. Modern rolling and heat-treatment processes ensure the production of finished products with low rolling stresses and a homogeneous crystalline structure.

S235JR belongs to the group of low-carbon steels, which means that it contains a limited amount of carbon (about 0.2%), which contributes to its ductility and ease of processing, while maintaining adequate strength and hardness. In addition, it may contain small amounts of other elements, such as manganese (up to 1.4%), which are added to improve certain mechanical properties.

S235JR steel mechanical properties

The strength of finished products depends on the wall thickness of the metallurgical product. There are 3 thickness ranges adopted, given in mm: t ≤ 16, 16< t ≤ 40 and 40 < t ≤ 100. The wall thickness affects the value of yield and tensile strength, as well as the load-bearing capacity (of the section or the whole element), which is extremely important when designing steel structures in the construction industry.

Tensile strength ranges from 360 to 510 MPa.
S235JR steel shows good technological properties, i.e. it is easy to shape in the cold, e.g. it is susceptible to bending, roll forming and drawing.

S235JR steel application

In summary, S235JR steel is a grade very often used for building structures, it is well weldable and resistant to brittle fracture. It is usually supplied in hot-rolled condition and can be used in a wide variety of structures, such as bridges, machinery and as a material for structural components designed for strength, as well as for structures for overhead line conductors.

S235JR vs S355J2 comparison

When comparing S235JR steel with another equally popular structural steel, S355J2, the first thing to note is that they differ in yield strength, i.e. 235 MPa or 355 MPa. A higher value of the stress required to initiate macroscopic plastic deformation is exhibited by S355J2 steel, and in connection with this it also shows higher strength, i.e. Rm ranges from 470 to 630 MPa. Another difference has been determined by the type designation JR and J2 and stands for impact strength i.e. the material's resistance to fracture under dynamic loading.

JR - impact strength of 27 J at 20℃

J2 - impact strength of 27 J at -20℃

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