PSI - Issue 28

Jesús Toribio et al. / Procedia Structural Integrity 28 (2020) 2378–2381 Jesús Toribio et al. / Procedia Structural Integrity 00 (2020) 000–000

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Fig. 4. Fracture cracking: (a) crack tip; (b) region near the crack tip.

4. Conclusions Fatigue crack surface of a spheroidized steel showed ductile micro-tearings produced by propagating the crack through the thin layer of proeutectoid cementite. The fracture is initiated at the fatigue crack tip in a fibrous zone by microvoid nucleation, which is transformed into a cleavage fractography (with microvoids between the facets of cleavage). In the zone near the crack tip, microvoids are observed in the large particles of cementite located in the proeutectoid layer, by decohesion with the matrix or by breakage. Acknowledgements The authors wish to kindly acknowledge the financial support provided by the following Spanish Institutions: Ministry for Science and Technology (MICYT; Grant MAT2002-01831), Ministry for Education and Science (MEC; Grant BIA2005-08965), Ministry for Science and Innovation (MICINN; Grant BIA2008-06810), Ministry for Economy and Competitiveness (MINECO; Grant BIA2011-27870), Junta de Castilla y León (JCyL; Grants SA067A05, SA111A07 and SA039A08) and Fundación Samuel Solórzano Barruso. References Chattopadhyay, S., Sellars, C.M., 1982. Kinetics of Pearlite Spheroidisation During Static Annealing and During Hot Deformation. Acta Metallurgica 30, 157–170. Hall, E.O., 1951. The Deformation and Ageing of Mild Steel: III Discussion of Results. Proceedings of the Physical Society. Section B 64, 747–753. Karlsson, B., Lindén, G., 1975. Plastic Deformation of Eutectoid Steel with Different Cementite Morphologies. Materials Science and Engineering 17, 153–164. Kim, E.S., Kim, I.S., 2000. Effect of Spheroidization on the Near-Threshold Fatigue Crack Growth in Ferrite-Pearlite Steel. Journal of Materials Science Letters 19, 367–369. Milligan, R.V., 1974. The Role of Carbide Morphology on Low-Cycle-Fatigue Behaviour of Iron-Carbon Alloys. Experimental Mechanics 1, 190– 195. Park, Y.J., Bernstein, I.M., 1979. The Process of Crack Initiation and Effective Grain Size for Cleavage Fracture in Pearlitic Eutectoid Steel. Metallurgical Transactions 10A, 1653–1664. Park, I.-G., Thompson, A.W., 1988. Ductile Fracture in Spheroidized 1520 Steel. Acta Metallurgica 36, 1653–1664. Petch, N.J., 1953. The Cleavage Strength of Poly-Crystals. Journal of the Iron and Steel Institute 174, 25–28. Rawal, S.P., Gurland, J., 1977. Observations on the Effect of Cementite Particles on the Fracture Toughness of Spheroidized Carbon Steels. Metallurgical Transactions 8A, 691–698. Rosenfield, A.R., Hahn, G.T., Embury, J.D., 1972. Fracture of Steels Containing Pearlite. Metallurgical Transactions 3, 2797–2804.