PSI - Issue 81

Jesús Toribio et al. / Procedia Structural Integrity 81 (2026) 140–142

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When this happens, final fracture takes place for purely mechanical reasons, so the distance x LAD has statistical significance, since it depends on the position of the pseudocolonies and thus on their frequency of appearance which is higher when cold drawing becomes heavier. The longer the mode I path (x I or x LAD ) in SCC processes, the slower the crack growth rate and the more delayed the final fracture, because in this case (mode I propagation) the crack advances by LAD perpendicularly to the oriented ferrite/cementite plates, thereby following the strongest crack path (before the crack deflection towards the weakest crack path ). This delay is the reason why the cold drawn wire is very resistant to SCC, while at the same time is strongly susceptible to the dangerous phenomenon of hydrogen assisted cracking (HAC), because in this latter case the crack is unable to propagate in mode I and the deviation suddenly appears, producing mixed mode propagation and a quite fast crack growth rate.

LAD

Fig. 2. Micromechanism of SCC by localized anodic dissolution (LAD).

6. Conclusion Heavily cold drawn pearlitic steels exhibit delayed anisotropy of stress corrosion cracking (SCC) behaviour , and there is a strong correlation between the microstructural orientation angles (at the two levels of the pearlitic colonies and lamellae) and the macroscopic crack deflection angles (representing the macroscopic crack paths), clearly demonstrating the influence of the oriented microstructure (and thus of the manufacture process by increasing cold drawing) on the macroscopic SCC behaviour of the steels, towards the weakest crack path . References Cherry, B.W., Price, S.M., 1980. Pitting, Crevice and Stress Corrosion Cracking Studies of Cold Drawn Eutectoid Steels, Corrosion Science 20, 1163 - 1184. Sarafianos, N., 1989. Environmentally Assisted Stress - Corrosion Cracking of High - Strength Carbon Steel Patented Wire, Journal of Materials Science Letters 8, 1486 - 1488. Toribio, J., Ovejero, E., 1997. Microstructure Evolution in a Pearlitic Steel Subjected to Progressive Plastic Deformation. Materials Science and Engineering A234 - 236, 579 - 582. Toribio, J., Ovejero, E., 1998a. Effect of Cumulative Cold Drawing on the Pearlite Interlamellar Spacing in Eutectoid Steel. Scripta Materialia 39, 323 - 328. Toribio, J., Ovejero, E., 1998b. Microstructure Orientation in a Pearlitic Steel Subjected to Progressive Plastic Deformation. Journal of Materials Science Letters 17, 1037 - 1040. Toribio, J., Ovejero, E., 1998c. Effect of Cold Drawing on Microstructure and Corrosion Performance of High - Strength Steel. Mechanics of Time - Dependent Materials 1, 307 - 319. Toribio, J., Ovejero, E., Toledano, M., 1997. Microstructural Bases of Anisotropic Fracture Behaviour of Heavily Drawn Steel. International Journal of Fracture 87, L83-L88.