Application of Instrumented Impact Test Results in Evaluating Ductility and Brittleness of SA508 Gr.3-Cl.2 Steel

The Charpy impact test was performed for nuclear steel material SA508 Gr.3-Cl.2 by using instrumented test method, and the force-displacement curve was recorded during the process. Crack forming energy and crack propagation energy of the material were calculated by using the method provided in GB/T 19748-2005. The results showed that crack forming energy gave priority to crack propagation energy below -27 ℃ and contrary above -27 ℃; crack propagation energy stood approximately above 20 ℃ and showed ductile fracture surface almost, crack propagation energy went down progressively at 20~-60 ℃ and ductile fracture surface changed into brittle fracture surface gradually, crack propagation energy went into lower lever below -60 ℃ and showed brittle fracture surface almost. The results showed a sound conformity to the traditional evaluating method (percent shear fracture).