ABSTRACT
Rolled weldable fine grain structural steels in Europe are standardized as S275, S355, S420 and S460 and available as normalized with suffix N or NL (EN 10025-3 2005) or thermo-mechanically rolled with suffix M or ML (EN 10025-4 2005). The N and M suffices have an impact strength category at –20 οC and the NL and ML suffices at –50 οC. The normalized and thermo-mechanical steels up to 460 N/mm2 yield strength are now permitted for use in all Eurocodes and may be considered as mild steel today. Structural hollow sections are covered by two codes, for products that are hot finished (EN 10210-1 2006, EN 10210-2 2006) and cold formed (EN 10219-1 2006, EN 10219-2 2006). They have an additional suffix H for hollow sections at the end of each steel grade. The hot finished hollow sections only cover normalized steels up to 460 N/mm2, whereas the cold formed hollow sections include both normalized and thermo-mechanical steels, up to 460 N/mm2.
