The tangential and axial impact toughness of steel S355NL for wind power tower flange (/% : 0.14C
0.22Si
1.35Mn
0.010P
0.002S
0.06Cr
0.01Mo
0.l0Ni
0.03Cu
0.40Ceq) at -20~-80℃ has been tested and analyzed. The results show that with decreasing test temperature the V-type impact energy of steel S355NL decreases
the ductile-brittle transition temperature of tangential specimen is lower than -80℃ ( average impact energy at -80℃ is 76.89 J) and the ductile-brittle transition temperature of axial specimen is about —65℃ (average impact energy at -60℃ is 96.10 J and that at -70℃ is 13.28 J )
the morphology of impact fracture transfers from ductile shear fracture to quasi cleavage fracture and until to complete cleavage fracture with "fan-shaped" cleavage pattern.