PAPER REFERENCE: 2C.84 APPROXIMATE EVALUATION OF ' DIRECTIONAL TOUGHNESS IN COLD DRAWN PEARLITIC STEELS

In this paper, an approximate procedure is proposed to estimate the fracture toughness of heavily drawn pearlitic steels in both longitudinal (wire axis) and transverse (perpendicular) directions, calculating the critical load at the pop-in situation (coincident with crack deflection) and at the catastrophic failure instant (final fracture which takes place at maximum load). The method is based on the experimental fact of anisotropic behaviour in this kind of steel, with crack deviation from the original direction in mode I, the deflection angle being almost 90°, which represents a propagation step aligned to the wire axis or cold drawing direction. After this 9O0-step, the crack propagates in a direction close to the original one transverse to the wire axis. These two propagation directions-perpendicular to each other- allow an estimation of the directional fracture toughness in axial and radial directions