S235J2W normalized atmospheric corrosion resistant weathering structural steel

Product Specification

S235J2W+N is a structural steel with improved atmospheric corrosion resistance. Due to its chemical composition, this material develops a patina with increased resistance against the atmospheric corrosion in comparison with non-alloyed structural steels.

Due to its restricted chemical composition, S235J2W+N STRUCTURAL STEEL has a better weldability compared to respective steels produced according to EN 10025-5.

S235J2W+N STRUCTURAL STEEL is used for instance in steel constructions like bridges and buildings.

Product description

Designation and range of application

S235J2W+N STRUCTURAL STEEL can be delivered in thicknesses from 8 to 150 mm according to our delivery program. Other dimensions are available on request.

S235J2W+N STRUCTURAL STEEL (material number 1.8961), specified in EN 10025-5. Under the designation S235J2W+N STRUCTURAL STEEL/S235J2W+N, CE-marking will be applied in thicknesses up to 150 mm according to EN 10025-1.

Under the designation S235J2W+N STRUCTURAL STEEL/S235J2W+N, the „marque NF-Acier“ (class 2 or 21) can be applied in thicknesses up to 150 mm according to NF EN 10025-5.

Chemical composition

For the ladle analysis the following limiting values are applicable in %:

Delivery condition

Normalized or normalizing rolling in accordance with EN 10025-5.

Mechanical and technological properties in the delivery condition

Tensile test at ambient temperature – transverse test

(a) If not apparent, the yield strength Rp0.2 is measured.

Impact test on Charpy-V-longitudinal specimens

The specified minimum value is the average of 3 tests. One individual value may be below the minimum average value specified, provided that it is not less than 70 % of that value. For plate thicknesses ≤ 12 mm the test can be carried out on Charpy-V-test specimens with reduced width, the minimum width of the specimens being 5 mm. Then, the minimum impact value decreases proportionally to the section of the test specimen.

Weld bead bend test

For plate thickness > 30 mm, S235J2W+N STRUCTURAL STEEL can be delivered with additional weld bead bend test in accordance with SEP 1390 (edition 1996) if specified at the time of the order (option 1).

Testing

Tensile and impact tests will be performed according to EN 10025-5 once per heat, 40 t and thickness range as specified for the yield strength. If agreed at the time of the order, the tests could be performed on each mother plate (option 2).

The preparation of the test units occurs in accordance with EN 10025-1 and EN10025-5. The tensile test is carried out in accordance with EN ISO 6892-1.

The impact test is carried out at -20 °C on longitudinal Charpy-V-specimens using a 2 mm striker in accordance with EN ISO 148-1.

Unless otherwise agreed, the test results are documented in a certificate 3.1 in accordance with EN 10204.

Order options

1) Weld bead bend test in accordance with SEP 1390 (Edition 1996),

2) Verification of the tensile and impact properties on each mother plate.

Plate identification

Unless otherwise agreed, the marking is carried out via steel stamps with at least the following information:

· Steel designation (S235J2W+N STRUCTURAL STEEL/S235J2W+N)

· Heat number

· Number of mother plate and individual plate

· Identification mark of the manufacturer

· Identification mark of the authorized inspection representative

Atmospheric corrosion resistance

Atmospheric corrosion resistance means that S235J2W+N STRUCTURAL STEEL - due to its chemical composition - presents an improved resistance against atmospheric corrosion because of the forming of an auto- protective layer on the base material depending on weather condition having a succession of dry and wet periods. This layer protects the surface and slows down the normal rust formation.

Generally, the corrosion velocity decreases with increasing service life. Even after the formation of the patina, a total stop of the corrosion process does not occur.

However, the patina offers - in comparison to unalloyed steels - a better protection against atmospheric corrosion in industrial, city or rural atmospheres, enabling the application of uncoated steels under certain circumstances.

Initial formation, time of development and protective effect of the patina on steels with improved atmospheric corrosion resistance are extremely depending on the constructional design and the atmospheric and environmental conditions in the respective case.

Processing

The entire processing and application techniques are of fundamental importance to the reliability of the products made from this steel. The user should ensure that his design, construction and processing methods are aligned with the material, correspond to the state-of-the-art that the fabricator has to comply with and are suitable for the intended use. The customer is responsible for the selection of the material. The recommendations in accordance with EN 1011-2.

Cold forming

Cold forming means forming below the maximum allowable stress relief temperature (generally < 580 °C).

S235J2W+N STRUCTURAL STEEL can be cold formed as any comparable structural steel in accordance with EN 10025. In case of higher cold forming ratios, i.e. edging on mechanical presses, it is advisable to consult the steel manufacturer prior to placing the order.

Hot forming

Hot forming means forming at temperatures above AC3 (~ 900 °C; austenitic phase). If possible, the hot forming has to be carried out at the normalizing temperature with following cooling in still air.

Flame cutting and welding

S235J2W+N STRUCTURAL STEEL has an excellent weldability under the condition that the general technical rules (see EN 1011) are observed. The fabrication by flame cutting and welding has to be carried out similarly to normal unalloyed structural steels of EN 10025 of the same strength and dimensions. However the hardenability of the steel is increased due to the Cu and Cr alloying. The preheat conditions must be adapted to the carbon equivalent. If necessary, the corrosion resistance of the welding deposit has to be assured by selection of adequate weld metals or other anti-corrosion measures.

Heat treatment

Welded joints of S235J2W+N STRUCTURAL STEEL are usually used in welded condition. If a stress relief heat treatment is necessary, a temperature of maximum 580 °C and a holding time of maximum 60 minutes with a heating and cooling speed of 70 - 80 °C/h is recommended.

General technical delivery requirements

Unless otherwise agreed, the general technical delivery requirements in accordance with EN 10021 apply.

Tolerances

Unless otherwise agreed, tolerances are in accordance with EN 10029, class A for the thickness and table 4, steel group L, for the maximum flatness tolerance. Smaller flatness tolerances can be agreed at the time of the order.

Surface quality

Unless otherwise agreed, the specifications will be in accordance with EN 10163-2, class A2.

General notes

If particular requirements are demanded and not covered in this material data sheet, please contact us with the specifications for our review and agreement prior to ordering.

 
 
Production process