COMPARISON OF REFERENCE TEMPERATURE T_0 FROM INSTABILITY K_(JC) AND K_(IC) FRACTURE TOUGHNESS

摘要

The application of the reference temperatures T_0 and RT_(To) according to ASTM E 1921 and ASME Code Cases N-629 or N-631, respectively, shall be established in the current revision of German KTA rules. The Master Curve reference temperature TO characterizes the fracture toughness of ferritic steels that experience onset of cleavage cracking at elastic, or elastic-plastic K_(JC)-instabilities, or both. The plane-strain fracture toughness, K_(IC), defined by ASTM E 399, is assumed to represent a size insensitive initiation based lower bound value. The majority of existing fracture toughness data are based on K_(IC)-values. More recent data are K_(JC), related to the issuing of ASTM E 1921 in 1997 and to the success of the Master Curve based T_0. Therefore, the possible difference between T_0 determined from K_(JC) and from K_(IC) was investigated with available data bases for RPV-steels. The comparison of T_0(K_(JC)) and T_0(K_(IC)) showed a 1:1 correlation proving equivalence of K_(JC) and K_(IC) in the determination of T_0.