EVALUATION OF WELD-JOINT FLAWS AS INITIATING POINTS OF BRITTLE FRACTURE

摘要

This report describes a study made of the conditions needed for initiation of a brittle fracture from flaws 4 in, or less in length. Experiments performed have demonstrated that residual and reaction stresses (local stresses) join with applied stresses to make up the total stress that is involved in the initiation of many brittle fractures. If local stresses are high in the vicinity of a flaw, then the applied stress may be low when brittle fracture initiates from that flaw pro?vided that the steel is at or near the nil ductility temperature (NDT). Stress con-ditions that are expected to exist in ship structures were incorporated in the test specimen. Various techniques were employed to determine the magnitude of the stresses in the area of the flaw front. Some brittle fractures were initiated from flaws 4 in, or less in length at an applied stress of less than 6000 psi, Thus the results provided some insight concerning the state of stress that probably ex?isted in structures that have failed in service at low applied stress.