Modification of Pre-Cracked Charpy Specimens for Surveillance Specimen Programs

Application of pre-cracked Charpy specimens with various depth of side-grooves is considered for fracture toughness prediction. Recommendations for prediction of temperature dependence of fracture toughness are given when using small-sized specimens with deep side-grooves. Test results of about 500 specimens, cut from materials with various degrees of embrittlement are presented. On the basis of 3D calculations by finite element method the procedure used in standard ASTM E 1921 for calculation of K_e and J, is developed for bending specimens with deep side-grooves. An attempt is undertaken to explain the obtained experimental data from the standpoints of the available criteria of brittle fracture based on calculation analysis of stress and strain fields (SSF) of SE(B)-10 specimens with various depths of side-grooves.