C in % max.for nominal product thicknes s in ≤ 16 mm Mn % (Max) Si % (Max) S % (Max) P % (Max) Nominal Yield strength Ys (MPa) Nominal ultimate tensile strength Us (MPa) 1 Q235B 0.2 1.4 0.35 0.045 0.045 GB/T 700-2006 235 370 GB/T 700-2006 2 A36 0.26 1.35 0.4 0.05 0.04 ASTM A36/A36M 250 400 ASTM A36/A36M 3 Q345B 0.2 1.6 0.55 0.04 0.04 GB/T 1591-1994 345 470 GB/T 1591-1994 4 Grade 50(345) 0.23 1.35