抄録
Observations of ductile fracture processes were made on the high strength materials of SNCM 8, HT 80, 2024-T4 aluminum alloy and a sintered steel. A special interest was put on the initiation of microvoids. Ductility of these materials was widely varied by the application of hydrostatic pressure up to 10000kg/cm2 and by the use of artificially necked (notched) specimens. It was found that the initiation of microvoids did not take place until very late in the fracture process and that the final fracture was triggered by the microvoid initiation over a wide range of ductility for these high strength materials. The critical condition for the microvoid initiation was discussed. The Mises equivalent stress was found to be constant for SNCM 8, HT 80 and 2024-T4. The local particle-matrix interface stress, which was estimated from the macroscopic stress and strain at fracture on the basis of the finite element analysis, was also found to be constant for SNCM 8 and HT 80.
