PSI - Issue 33

Jesús Toribio et al. / Procedia Structural Integrity 33 (2021) 1203–1208 Jesús Toribio / Porcedia Structural Integrity 00 (2021) 000–000

1207

5

Fig. 6. Axial micro-cracks generated in a heavily drawn pearlitic steel (commercial prestressing steel) during the manufacture by cold drawing.

Fig. 7. Fracture surfaces in a hot rolled bar (left) and a cold drawn wire (right). Heavily cold drawn steels (Fig. 8) exhibit locally anisotropic fracture behavior due to the presence of multiple micro-cracks oriented and aligned along the drawing direction (created by debonding between the inclusions and the pearlitic matrix) and the triaxial stress state (with radial and hoop components) generated after necking. Both factors are relevant to create an anisotropic fracture in heavily cold drawn pearlitic steels in which there is a coexistence of: (i) elevated stress values; (ii) high level of stress triaxiality; (iii) many micro-cracks created from the inclusions, aligned and oriented along the drawing axis. The hoop stress σ θ during plastic instability ( necking ) before final fracture induces locally anisotropic fracture with crack deflections and appearance of crests and valleys.

Fig. 8. Anisotropic fracture behavior in a cold drawn pearltic steel.