What do the letters and numbers in S355J2+N Quality signify?
Generally chosen for designs that will operate in cold weather conditions and require high mechanical strength but not corrosion resistance or wear resistance, these are non-alloy structural steels that have been refined and homogenized through a heat treatment process called Normalization to achieve a tough and ductile structure.
The initial "S" stands for "Structural," indicating that the material belongs to the group of structural steels. The number 355 represents the material's yield strength value. S355J2 grade steels show resistance without permanent deformation up to a load of 355 MPa in an impact test at -20°C with 27 Joules of energy.
The letter "J" indicates that the impact test was conducted with 27 J of energy.
The number "2" indicates that the test was performed at a temperature of -20°C.
The "+N" signifies that the material has undergone normalization.
S ⇒ Structural
355 ⇒Minimum yield strength of 355 MPa
J ⇒ Minimum impact energy of 27 Joules
2 ⇒At -20°C temperature
+N ⇒Normalization