Estimation of Fracture Toughness J_(IC) by Miniature Specimen Hydraulic Bulge Test

摘要

The fracture toughness tests and a new miniature specimen technology named hydraulic bulge test (HBT) of 3CrlMol/4V at four service time were carried out. Four J-R resistance curves by single-specimen method with one inch CT specimens were obtained to compute the J_(IC). Different definitions of equivalent fracture strain according to the section morphologies of HBT testing specimens were compared, and fracture energy of miniature specimens with three different thicknesses (0.4mm, 0.5mm and 0.6mm) were also calculated. Results showed that the typical HBT load-deflection curve can be divided into four sections like SPT curve. Equivalent fracture strain ε_ε and fracture energy E_(HB) can be chosen as two fracture parameters for the HBT specimen. Ductile fracture toughness J_(IC) can be related approximately linearly to both the equivalent fracture strain ε_ε and fracture energy E_(HB)