CRITICAL NOTCH(CRACK)SIZE AS A CHARACTERISTIC PARAMETER EVALUATING CRYOGENIC BRITTLENESS IN LOW CARBON STEEL

摘要

The effect of notch depth on the cryogenic fracture behavior has been studied using a low car-bon steel.An analysis was made for the fracture features at T_c~*(cryogenic brittleness-char-acteristic temperature)at which the facture load reaehes a valley value.Furthermore,accord-ing to the experimental results and engineering design practice,a concept of critical notch(crack)’size for cryogenic brittleness,a_c,as well as its limit value a_c~*,was put forward andrecommended to be a basic characteristic parameter for controlling the brittleness.Mathematical derivation was carried out to give the expression of a_c and a_c~*,the reliabilityof which was verified by the modeling tests under both static and cyclic loading conditions.