Effect of strain rate on the fracture toughness of borated stainless steel

Borated stainless steel, B-SUS304P-1, has been used for storage and transportation metal casks in the nuclear industry. Assuming various accidents, it is important to know the effect of strain rate on the fracture toughness of B-SUS304P-1. In the present study, image processing is used to evaluate the fracture toughness, because it is able to evaluate identically under various strain rate. Displacement field around a crack tip is obtained by a digital image correlation (DIC) method. J-integral and crack growth increment are determined by the DIC method and the fracture resistance curve is obtained. This method was applied for the fracture toughness test based on the ASTM Standard E-1820, and fracture resistance curves of the standard and the DIC method were compared. The results reveal that the DIC method is unable to evaluate the plane strain fracture toughness, however, it is possible to investigate the influence of the strain rate on the fracture toughness. It is suggested that the effect of the strain rate on the fracture toughness of B-SUS304P-1 is small by comparing the fracture resistance curves obtained by the DIC method under various strain rate conditions. (author)