Fine-grain structural steels, thermomechanically rolled

Usage

The series of thermomechanically rolled fine-grain structural steels is characterized by a minimum yield strength of 275 - 460 MPa, by good weldability and high resistance to brittle cracking. They are used above all for highly stressed welded structures in the construction of bridges and steel structures.
The cryogenic grades S...ML are available for special applications at 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 excellent cold-forming properties. Cold-bordering, cold-flanging, cold-bending and cold-folding are possible.

Standards

Europe Material no. DE IT GB US Salzgitter Flachstahl FK1)
EN 10025-4 SEW 083 UNI 7382 BS 4360 ASTM
S275M 1.8818 - Fe E 275 KGTM - - SBS 275 TM A
S275ML 1.8819 - Fe E 275 KTTM - - SBS 275 TMK A
S355M 1.8823 StE 355 TM Fe E 355 KGTM - A 572 Gr. 50  SBS 355 TM  B
S355ML 1.8834 TStE 355 TM Fe E 355 KTTM  50 EE A 633 Gr. C SBS 355 TMK B
S420M 1.8825 StE 420 TM Fe E 420 KGTM - A 572 Gr. 60 SBS 420 TM C
S420ML 1.8836 TStE 420 TM Fe E 420 KTTM - A 633 Gr. E SBS 420 TMK C
S460M 1.8827 StE 460 TM Fe E 460 KGTM  - A 572 Gr. 65 SBS 460 TM C
S460ML 1.8838 TStE 460 TM Fe E 460 KGTM 55 EE A 572 Gr. 65 SBS 460 TMK C

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

Grade C Si Mn P S1) N Altotal2) Ni V Mo Cu3) CE4)
max. max. max. max. max. max. min. max. max. max. max. max.
S275M 0.13 0.50 1.50 0.030 0.025 0.015 0.02 0.30 0.08 0.10 0.55 0.34
S275ML 0.13 0.50 1.50 0.025 0.020 0.015 0.02 0.30 0.08 0.10 0.55 0.34
S355M 0.14 0.50 1.60 0.030 0.025 0.015 0.02 0.50 0.10 0.10 0.55 0.39
S355ML 0.14 0.50 1.60 0.025 0.020 0.015 0.02 0.50 0.10 0.10 0.55 0.39
S420M 0.16 0.50 1.70 0.030 0.025 0.025 0.02 0.80 0.12 0.20 0.55 0.435)
S420ML 0.16 0.50 1.70 0.025 0.020 0.025 0.02 0.80 0.12 0.20 0.55 0.435)
S460M 0.16 0.60 1.70 0.030 0.025 0.025 0.02 0.80 0.12 0.20 0.55 0.456)
S460ML 0.16 0.60 1.70 0.025 0.020 0.025 0.02 0.80 0.12 0.20 0.55 0.456)
  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    
    When the steel is suitable for hot dip galvanizing, CE  is raised by 0.2%.
  5. For thicknesses > 16 mm, a maximum carbon equivalent of 0.45% is acceptable, if agreed upon ordering.
  6. For thicknesses > 16 mm, a maximum carbon equivalent of 0.46% is acceptable, if agreed upon ordering.


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

Mechanical properties1)

Grade Min. yield strength2) Tensile strength Min. total elongation2) [%]
[MPa] [MPa] LO = 5,65 √SO
e ≤ 16 e > 16 e ≥ 3
S275M 275 265 370 - 530 24
S275ML 275 265 370 - 530 24
S355M 355 345 470 - 630 22
S355ML 355 345 470 - 630 22
S420M 420 400 520 - 680 19
S420ML 420 400 520 - 680 19
S460M 460 440 540 - 720 17
S460ML 460 440 540 - 720 17
  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

Bending Radius

Bending Radius
transverse parallel
S275 2 * e 2,5 * e
S355 2 * e 2,5 * e
S420 4 * e    5 * e
S460 4 * e    5 * e

Notch impact energy

Grade Position of samples Minimum value of notch impact energy1) [J] at a test temperature of [°C]
longitudinal 20 0 -10 -20 -30 -40 -50
S275M 55 47 43 40 - - -
S355M 55 47 43 40 - - -
S420M 55 47 43 40 - - -
S460M 55 47 43 40 - - -
S275ML 63 55 51 47 40 31 27
S355ML 63 55 51 47 40 31 27
S420ML 63 55 51 47 40 31 27
S460ML 63 55 51 47 40 31 27
transverse 20 0 -10 -20 -30 -40 -50
S275M 31 27 24 20 - - -
S355M 31 27 24  20 - - -
S420M 31 27 24 20 - - -
S460M 31 27 24 20 - - -
S275ML 40 34 30 27 23 20 16
S355ML 40 34 30 27 23 20 16
S420ML 40 34 30 27 23 20 16
S460ML 40 34 30 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, not least due to their reduced carbon content and the low carbon equivalent value.

In general, pre-heating prior to welding is not necessary due to the low tendency to cold-cracking. In any case, the information provided in ‘Stahl-Eisen-Werkstoffblatt’ (Iron and steel material sheet) 088 should be observed.

However, the quality of the weld joint depends on the welding process, the welding conditions and the selection of the correct filler metals. Gas welding should not be used.

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

These fine-grain structural steel grades are not suitable for heat treatment above 580 °C. Stress relief annealing (530 - 580 °C) is required only if called for in the regulations or if manufacturing conditions make a reduction of the residual welding stresses appear useful. The holding time should be between 30 and 60 minutes.

Condition of delivery, scope of testing and certificate

The provisions of EN 10025-4, chapters 6.3 und 8 shall apply for delivery and inspection. The products are thermomechanically rolled and delivered with a corresponding reference.

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