PSI - Issue 39

Jesús Toribio et al. / Procedia Structural Integrity 39 (2022) 475–478 Author name / Procedia Structural Integrity 00 (2021) 000–000

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(a) (b) Fig. 2. Relationship between the microstructure of the steels and the crack paths: (a) evolution with cold drawing of the orientation angles of colonies and lamellae in the pearlitic microstructure; (b) evolution with cold drawing of the macroscopic crack angle, step height and mode I propagation distance in SCC conditions; the angles α , α ' and θ are measured from the radial direction (transverse to the wire axis). 6. Closing remarks The strong plastic deformations produced during manufacture affect the steel microstructure, it becoming progressively oriented in the wire axis direction as a direct consequence of cold drawing. This happens at the two basic microstructural levels: the pearlite colony and the pearlitic lamellae. The afore-said microstructural orientation influences the microscopic and macroscopic aspects of the fracture mode in aggressive environments, showing a general evolution from crack propagation in mode I for hot rolled and slightly drawn steels to mixed mode propagation (with strong mode II component) for heavily drawn steels. Under SCC conditions 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), which clearly demonstrates the influence of the oriented microstructure (and thus of the manufacture process by increasing cold drawing) on the macroscopic SCC behaviour of the steels. References Borchers, Ch., Kirchheim, R., 2016. Cold-Drawn Pearlitic Steel Wires. Progress in Materials Science 82, 405-444. Cherry, B.W., Price, S.M., 1980. Pitting, Crevice and Stress Corrosion Cracking Studies of Cold Drawn Eutectoid Steels, Corrosion Science 20, 1163-1184. Embury, JD., Fisher, RM., 1966. The Structure and Properties of Drawn Pearlite. Acta Metallurgica 14, 147-159. Langford, G., 1977. Deformation of Pearlite. Metallurgical Transactions 8A, 861-875. Ridley, N., 1984. A Review of the Data on the Interlamellar Spacing of Pearlite. Metallurgical Transactions 15A, 1019-1036. 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., Lancha, A.M., 1998. Anisotropic Stress Corrosion Cracking Behaviour of Prestressing Steel, Materials and Corrosion 49, 34-38. 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.