Evolution of the Microstructure and Properties for 2000 MPA Bridge Cable Steel

Abstract

In this paper, the microstructure, texture and mechanical properties of pearlite steel wires produced using different processes were investigated by mechanical testing and electron microscopy techniques including combining SEM, TEM and XRD to reveal the evolution of the microstructure and properties of 2000 MPa bridge cable steel. The experiments were carried out under industrial conditions. The microstructural observations indicate that the orientation of the lamellar pearlite in the steel rod is random and that patenting produces a fully pearlitic microstructure with a fine pearlitic interlamellar spacing. The pearlitic lamellae of the wires tilt and stretch toward the drawing direction during cold drawing. Although the cementite of the cold drawn wires retains a laminar shape, partial fragmentation of the cementite lamella occurs. A large number of SBs appear in the galvanized steel wire, and fragmentation of the cementite lamella is more obvious. After cold drawing, the orientation of the 〈110〉 texture intensifies and becomes dominant. However, the intensity of the 〈110〉 texture decreases slightly after galvanizing. The results from the mechanical experiments show that the hardness and tensile strength of the steel wires increase rapidly after cold drawing before reaching a peak. However, the hardness and tensile strength of the galvanized steel wire decrease slightly.