PSI - Issue 28

Jesús Toribio et al. / Procedia Structural Integrity 28 (2020) 2386–2389 Jesús Toribio et al. / Procedia Structural Integrity 00 (2020) 000–000

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For achieving a better understanding of the observed residual stress redistribution, the role of plastic strain is a key issue. Thus, when the fatigue loading is below the material yield strength (  = 0.90), plastic strains only appear locally in the tensile zone of the residual stress profile. The influence of the cyclic loading on the stress reduction can be evaluated in terms of a dimensionless parameter (  ), that is defined as ratio of the reduction of the axial stress at the wire surface (  ) and the axial residual stress itself (  ). This way, Fig. 4 shows the variation of such a parameter (  ) with the maximum fatigue loading (  max ). According to results, a linear growing trend with the maximum fatigue loading is observed for the relative stress reduction at the wire surface. It being as high as 48% for maximum fatigue loading within the elastic regime (Loading I,  = 0.90), and as high as 80% for the highest loading considered (Loading III,  = 1.15) within the fully plastic regime in material behaviour.

0 20 40 60 80 100 1100 1200 1300 1400 1500 1600  (%)  max (MPa) Fig. 4. Variation of the relative stress reduction at the wire surface with the maximum stress.

4. Conclusions As a result of the manufacturing process of commercial prestressing steels wires (cold drawing), a residual stress state is generated in the wire (tensile stress near the surface and compressive one in the wire core). A reduction of such a stress state and a consequent redistribution of the residual stress state is caused by the fatigue loading. This stress reduction grows linearly with the maximum fatigue loading applied to the wire. This way, the highest stress reduction and a quasi-uniform distribution of axial effective stress can be achieved for cyclic loading with a maximum load exceeding the material yield strength. References Perrin, M., Gaillet, L., Tessier, C., Idrissi, H., 2010. Hydrogen embrittlement of prestressing cables. Corrosion Science, 52, 1915–1926. Sant´Anna, A.M.S., Bastos, I.N., Rebello, J.M.A., Fonseca, M.P.C., 2016. Influence of hydrogenation on residual stresses of pipeline steel welded joints. Materials Research, 19, 1088–1097. Toribio, J., Lorenzo, M., Vergara, D., Kharin, V., 2011. Effects of manufacturing-induced residual stresses and strains on hydrogen embrittlement of cold drawn steels. Procedia Engineering, 10, 3540–3545. Toribio, J., Lorenzo, M., Vergara, D., Kharin, V., 2011. Hydrogen degradation of cold drawn wires: a numerical analysis of drawing-induced residual stresses and strains. Corrosion, 67, 5001–5009. Yang, F., Jiang, J.Q., Wang, Y., Fang, C.M.F., Zhao, K.L., Li, W., 2008. Residual stress in pearlitic steel rods during progressively cold drawing measured by X-ray diffraction. Materials Letters, 62, 2219–2221. Lillard, R.S., Enos, D.G., Scully, J.R., 2000. Calcium hydroxide as a promoter of hydrogen absorption in 99.5% Fe and a fully pearlitic 0.8% C steel during electrochemical reduction of water. Corrosion, 56, 1119–1132.