Abstract: Instrumented impact tests were carried out on a WX52 steel and its welded joint by using Charpy V-notch(CVN)specimens and precracked Charpy V-notch (PCVN) sppecimens.Significance of dividing E_t into E_f and E_p(E_f-pre-maximumload energy in the load-deflection curve,E_p-post-maximum load energy in the load-deflection curve,E_t=E_t+E_p) was discussed.Straight line relation between E_p and E_t was concluded under test condition.The relation was insensitive to microstructure,material state,such as rolling or casting and fracture mode over a certain range of material strength.The E_f/E_t value decreased with increasing strain concentration at the same time as the E_p/E_t value increased.A peak of the E_f/E_t values appeared at the T_d temperature in the E_t-T℃ relation curve,whilst,on the other hand,a valley point of the E_p/E_t values then occurred.