PSI - Issue 59

Jesús Toribio et al. / Procedia Structural Integrity 59 (2024) 131–136 Jesús Toribio / Procedia Structural Integrity 00 ( 2024) 000 – 000

132

2

Keywords: eutectoid steel; prestressing steel; pearlitic steel; cold drawing; microstructural evolution; microstructural orientation; pearlite interlamellar spacing decrease; hydrogen embrittlement; hydrogen-assisted micro-damage; tearing topography surface. 1. Introduction Both previous mechanical history and surrounding physico- chemical environment affect material’s behavior, thereby recalling the ideas proposed by Baruch de Spinoza about the hetero-determined nature of human being. In this framework, José Ortega y Gasset formulated “I am I and my circumstance”. Paraphrasing José Ortega y Gasset, Toribio (1992a; 2000) established the innovative idea that “the material is itself and its circumstance” emphasizing the depen dence of material’s performance on mechanical and environmental factors (the circumstance in the Orteguian sense), recalling the words of the Spanish major poet Antonio Machado “hoy es siempre todavia”, and Thomas Stearns El iot’s “and all is always now” (T oribio, 2000). This paper deals with hydrogen effects on progressively drawn pearlitic steel wires. (Toribio, 1992b; 2004; 2006). In this case, the first role of circumstance is played by the manufacture process by increasing cold drawing during which a strain hardening mechanism is activated (Embury and Fisher, 1966; Gil-Sevillano, 1986; Toribio, 2004; Toribio et al., 2014; Toribio, 2017). The second role of circumstance is played by hydrogen, reviewing previous work on hydrogen degradation (HD), hydrogen embrittlement (HE) or hydrogen-assisted micro-damage (HAMD) of progressively drawn pearlitic steels. Although the classical term of HE is used, the concept of HD is preferred, as used by the European Structural Integrity Society (ESIS) in its TC10 Committee of Environmentally Assisted Cracking (EAC) together with a Sub-Committee on HD (Toribio and Nykyforchyn, 2017a; 2017b). 2. Progressive (multi-step) cold drawing of pearlitic steels Manufacture of prestressing wires is made by progressive (multi-stage) cold drawing of pearlitic steels to increase the strength by a strain hardening mechanism. Fig. 1 shows two views of a real cold drawing chain and a schematic presentation of the cold drawing process with multiple passes.

(a)

(b)

Fig. 1. Manufacture of prestressing wires by progressive cold drawing: (a) two photographs of a real ( in situ ) cold drawing procedure in the factory; (b) scheme of a typical drawing process with six passes.