Abstract
The effect of weld profile on the fracture toughness of bond has been investigated. The engineering criterion for the brittle fracture initiation under mixed mode (opening mode, I, and tearing mode, III), was studied on the basis of COD-concept.
The following conclusions have been developed:
(1) In the case where the part of bond has lower toughness as compared with that of weld metal and heat-affected zone, and where the embrittle zone is relatively wide as in the case of welded joint in large heat input, the critical COD, δc, of bond for the welded joint with V, Y or X type weld profile nearly equals to that with I, _??_ or K type ones. All fatigue notches in these test specimens are located perpendicularly to the surface of plate.
(2) For a crack having its inclination between 65°and 90°to the surface of plate where the mixed mode condition prevails, the brittle fracture initiates when the COD corresponding to the opening mode, δI, reaches to the critical COD, δc, but the effect of COD corresponding to the tearing mode, δIII, can be hardly observed.
