PSI - Issue 26

Jesús Toribio et al. / Procedia Structural Integrity 26 (2020) 348–353 Toribio / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction Cold drawn pearlitic steels are important structural materials used in wire form as components of prestressed concrete in civil engineering. Their mechanical performance in service is excellent due to their high yield strength (YS) and ultimate tensile strength (UTS). This paper analyzes the hierarchical microstructural evolution in the afore said materials in the conceptual frame of the Spanish writers Fray Luis de León and Miguel de Cervantes, the painters Maurits Cornelis Escher and Victor Vasarely and the composer Johann Sebastian Bach. 2. Hierarchical microstructure in cold drawn pearlitic steels The hierarchical microstructural evolution in pearlitic steels during cold drawing (at the two levels of pearlitic colonies and lamellae) was studied by Toribio and Ovejero (1997, 1998a, 1998b, 1998c), showing the following trends: slenderizing of the colonies, decrease of interlamellar spacing and orientation in the direction of cold drawing (wire axis) of both the colonies and the lamellae. Fig. 1 shows the two microstructural levels (pearlite colonies and Fe/Fe 3 C lamellae) at the final stage of microstructural evolution after cold drawing, i.e., the two micrographs of Fig. 1 correspond to a heavily cold drawn pearlitic steel wire (commercial prestressing steel), showing the orientation and alignment of both colonies and lamellae in the cold drawing (wire axis) direction.

Fig. 1. Orientation of pearlitic colonies (left) and ferrite/cementite lamellae (right) in a direction quasi-parallel to the wire axis or cold drawing direction (represented by the vertical side of the micrographs) in heavily cold drawn pearlitic steel. 3. Hierarchical microstructural evolution in cold drawn pearlitic steels This section summarizes the quantitative metallography performed on progressively cold drawn pearlitic steels. To this end, and to evaluate the microstructural orientation, the angle  (Fig. 2) is defined between the main orientation of the lamellae and the wire axis or cold drawing direction, i.e.,  = 45º means randomly oriented microstructure, whereas  = 0º i ndicates a fully oriented microstructure.

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Fig. 2. Angle  between the lamellae and the wire axis or cold drawing direction e z .