Fine-grain structural steels, normalized rolled

Usage

The series of normalized rolled fine-grain structural steels is characterized by a minimum yield strength of 275 - 355 MPa, by good weldability and high resistance to brittle fracture. These grades are used above all for manufacturing highly stressed welded structures in the construction of heavy machinery, bridges and steel structures.

The special grades S...NL are available for application temperatures below -20 °C.

The user of these steel grades must make sure that his calculation, design and processing methods are appropriate for the material. The welding technique used must be suitable for the intended application and comply with the state-of-the-art.

The steel grades of this series offer good cold-forming and hot-forming properties without negatively affecting the material properties. These steel grades are therefore also suitable for cold-bordering and cold-flanging as well as for cold-bending and folding.

Bending radius:

2.0* nominal thickness, for bending axis transverse to rolling direction

2.5* nominal thickness for bending axis parallel to rolling direction

With cold-forming above 5% or hot-forming outside of the temperature range or 1.050 - 850 °C as well as after excess times, the plates should be subsequently normalized at 880 - 930 °C. The holding time is approx. 0.5 minutes per millimeter of plate thickness.

We would like to draw the user's attention to Stahl-Eisen-Werkstoffblatt’ (Iron and steel material sheet) 088. 

Standards

Europe Material no. DE FR IT GB ES US Salzgitter Flachstahl FK1)
EN 10025-3 DIN 17102 2) NFA 36-201 UNI 7382 BS 4360 UNE 36081 ASTM
S275N 1.0490 StE 285 - Fe E 285 KGN 43 E AE 285 KG - SBS 275 A
S275NL 1.0491 TStE 285 - Fe E 285 KTN 43 EE AE 285 KT A 633 Gr. A SBS 275 K A
S355N 1.0545 StE 355 E 355 R Fe E 355 KGN 50 E AE 355 KG - SBS 355 B
S355NL 1.0546 TStE 355 E 355 FP Fe E 355 KTN 50 EE AE 355 KT A 633 Gr. SBS 355 K B
  1. FK = Tensile strength class
  2. invalid standard

Chemical composition in percent by weight [%] (Heat analysis)

Grade C Si Mn P S1) N Altotal2) Cu3) Ni V CE4)
max. max. max. max. max. min. max. max. max. max.
S275N 0.18 0.40 0,50 - 1,50 0.030 0.025 0.015 0.02 0.55 0.30 0.05 0.40
S275NL 0.16 0.40 0,50 - 1,50 0.025 0.020 0,015 0.02 0.55 0.30 0.05 0.40
S355N  0.20 0.50 0,90 - 1,65 0.030 0.025 0.015 0.02 0.55 0.50 0.12 0.43
S355NL 0.18 0.50 0,90 - 1,65 0.025 0.020 0.015 0.02 0.55 0.50 0.12 0.43
  1. A sulfur content of max. 0.010% can be arranged for all products, if agreed upon ordering (e.g. for railways).
  2. The minimum value for the Altotal content shall not apply if the steel contains sufficient quantities of nitrogen-fixing elements.
  3. Cu content of more than 0.04% can cause hot shortness during hot forming.
  4. Maximum carbon equivalent value
    CE = C + Mn / 6 + (Cr + Mo + V) / 5 + (Cu + Ni) / 15


The following limitation shall additionally apply to all steel grades:
Ti ≤ 0.05 %, Nb ≤ 0.05 %, Cr ≤ 0.30 %, Mo ≤ 0.10 %

Mechanical properties1)

Grade Min. yield strength2) Tensile strength Min. total elongation [%]2)
[MPa] [MPa] LO = 5,65 √SO
e ≤ 16 e > 16 e ≥ 3
S275N 275 265 370 - 510 24
S275NL 275 265 370 - 510 24
S355N 355 345 470 - 630 22
S355NL 355 345 470 - 630 22
  1. The tensile test values given in the table apply to longitudinal samples; in case of strip and sheet steel of widths of ≥ 600 mm they apply to transverse samples.
  2. e = Nominal thickness in  mm

Notch impact energy

Grade Position of samples Minimum value of both impact energy1) [J] at a test temperature of [°C]
longitudinal 20 0 -10 -20 -30 -40 -50
S275N 55 47 43 40 - - -
S355N 55 47 43 40 - - -
S275NL 63 55 51 47 40 31 27
S355NL 63 55 51 47 40 31 27
transverse 20 0 -10 -20 -30 -40 -50
S275N 31 27 24 20 - - -
S355N 31 27 24 20 - - -
S275NL 40 34 34 27 23 20 16
S355NL 40 34 34 27 23 20 16
  1. Average values of 3 samples; one individual value may fall short of the required minimum value by not more than 30 %.
    The sample width shall equal the product thickness if the latter is between 6 - 10 mm, the tests being performed using samples which are similar to Charpy-V samples. The values specified in the table above are to be reduced proportionally to the sample width.

Welding

The fine-grain structural steel grades of this series can be perfectly welded both manually and using automatic equipment by means of all known welding processes. However, the quality of the weld joint depends on the welding process, the welding conditions and the selection of the correct filter metals.

The welding wires and electrodes approved in this strength category must be used as filter metals. Basic coated electrodes are recommended for manual welding.

In general, pre-heating prior to welding or torch -cutting is not necessary for the steel grades S275N and S275NL. At outside temperatures below +5 °C, plates of all other grades of this series should be preheated to 150 °C (see also Stahl-Eisen- Werkstoffblatt [iron and steel material sheet] 088).

Subsequent normalizing or stress relieve annealing is required only if called in the regulations or if operating and manufacturing conditions make a reduction of the residual welding stresses appear useful. With stress relieve annealing at 530 - 580 °C, the holding time should be 2 minutes per millimeter of plate thickness, not fall short of 30 minutes and not significantly exceed 60 minutes.

Excessively high annealing temperatures or excessively long annealing times bear the risk of reducing the strength values to below the condition of delivery.

In addition to this, the guidelines for processing these steel grades according to Stahl-Eisen-Werkstoffblatt (Iron and steel material sheet) 088 must be observed.

Condition of delivery, scope of inspections and certificate

inspections and certificate The provisions of EN 10025-3 shall apply for delivery and inspection. The products are delivered normalized rolled.

Certificates according to DIN EN 10204 can be supplied as follows: IT, DUN, FAX, e-mail, paper.