S355 is a non-alloy European standard (EN 10025-2) structural steel, most commonly used after S235 where more strength is needed. It got great weldability and machinability, let us see more mechanical details of this steel. Identification of Different S355 S – stands for structural steel 355 – stands for minimum yield strength (though it will vary based on thickness, refer below section for more details) Normally S355 will have following variation based on impact strength at different temperatures, as steel become more brittle when temperature drops. If your structure need to withstand -20°C, it’s better and safer to choose S355J2.   S355JR – Can withstand an impact energy of 27J at +20°C S355J0 – Can withstand an impact energy of 27J at 0°C S355J2 – Can withstand an impact energy of 27J at -20°C S355K2 – Can withstand an impact energy of 27J at -30°C (40J at -20°C)   And sometime followed by a letter H, like S355J2H, here H stands for hollow section. S355 is commonly supplied to the following standards:- BS EN 10025 BS EN 10277 BS EN 10250