A weldable normalized structural steel for large offshore structures with excellent toughness and weldability

Industeel®S355G10+N is a normalized structural steel plate grade with a nominal minimum yield strength of 325MPa* dedicated to large offshore structures in the North Sea and similar environments.
Thanks to the application of Option 18 of EN10225, the weldability of the steel is prequalified with a documentary file that has been reviewed by DNV-GL and Lloyd’s Register, making its implementation easier.
Its extreme purity with very low sulphur and phosphorus contents, as well as its adapted chemical analysis, makes Industeel®S355G10+N easy to cut, shape and weld, and provides excellent impact toughness and CTOD properties in the very large sizes available.
Industeel®S355G10+N is elaborated through Electric Arc Furnace (EAF) melting of selected scraps with fine grain practice, vacuum treatment and ingot casting to provide the necessary characteristics of the material.
The steel is rolled in plates with a quarto mill and finished using a separate normalizing heat treatment.
* 1 MPa = 1 N/mm²


EN10225:2009      S355G10+N – plates (to 150 mm thickness per the standard, and above)

Industeel®S355G10+N has been qualified to the following requirements of EN10225:2009

Option 12 (strain-ageing testing)
Option 13 (through-thickness testing)
Option 18 (Weldability testing)

This prequalification has been reviewed and approved by DNV-GL and Lloyd’s Register.
The grade can be delivered according to NORSOK M-120 Ed. 5 datasheet MDS-Y20 Rev.5 and at thicknesses above the maximum defined in the standard.

Chemical analysis – weight %, maximum unless a range is indicated

C Si Mn P S Cr Mo Ni Al Cu
0.12 0.15


1.65 0.008 0.002 0.20 0.08 0.70 0.015




N Nb Ti V B Nb+V Nb+V+Ti CEV Pcm
0.010 0.030 0.025 0.060 0.0005 0.06 0.08 0.43 0.22

CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Cu+Ni)/15
Pcm = C + Si/30 + (Mn+Cu+Cr)/20 + Ni/60 + Mo/15 + V/10 + 5 B


Mechanical properties


Thickness range (mm) Yield Strength ReH (MPa) Tensile Strength Rm (MPa) Yield to tensile strengths ratio Elongation on base 5,65 √S0 A(%) Through thickness reduction of area Z (%)
80-255 Minimum 325 460-620 Minimum 0.85 Minimum 22 Minimum 35

Charpy Impact tests

Minimum values according to EN10225 Table 7

Test temperature Transverse direction impact test sub-surface Transverse direction impact test mid-thickness
-40°C Minimum 50 J Minimum 50 J


EN10225:2009 Option 18 has been prequalified for Industeel®S355G10+N according to Norsok MDS-Y20

Temperature As welded condition 580°C nominal PWHT condition
-10°C Minimum 0.25 mm Minimum 0.20 mm



Download the complete datasheet

Technical data and information are to the best of our knowledge at the time of publication. However, they may be subjected to some slight variations due to our ongoing research programmes. Therefore, we suggest that information be verified at time of enquiry or order. Furthermore, in service, real conditions are specific for each application. The data presented here are for the purpose of description only, and can be considered as guarantees only when written formal approval has been provided by our company. Industeel reserves the right to change its product range at any time without prior notice.