FRAGMENTATION OF AS-DRAWN PEARLITIC STEEL WIRES DURING TORSION TESTS

During free end torsion tests of cold drawn eutectoid steel wire, prim ary fracture frequently causes further fragmentation of the wire. The size and orientation distribution of the pre-existing microcracks at t he moment of the primary fracture, and the unloading stress waves dete rmine the secondary fracturing behaviour. A model has been developed t o predict the distribution of the position of the first secondary frac ture. A very good agreement is obtained between measured and calculate d results. Moreover, as a by-product of the calculation, the delaminat ion toughness of the drawn wires has been estimated to have a value be tween 6.8 and 16.4 MPa root m, which, on the scarce evidence available for this important material parameter, seems very plausible. (C) 1998 Elsevier Science Ltd. All rights reserved.