Micro-structure-property relationship of heavily drawn steel wires for large span suspension bridge cables.

This article focuses on the micro-structure-property relationship of heavily cold-drawn pearlitic steel wires used in large-span suspension bridge cables, emphasizing the role of cementite deformation during the drawing process. The study reveals that cementite lamellae transform from single crystals to nano-crystals with increasing drawing strain, particularly beyond a critical strain of 1.37, which corresponds to a reversal in yield strength behavior. Initially, yield strength decreases due to nodule rotation and slip (inverse Hall-Petch effect), but subsequently increases as flat nodules limit these movements and solid solution strengthening arises from carbon atom migration from cementite to ferrite. Molecular dynamics simulations and high-resolution transmission electron microscopy demonstrate simultaneous dislocation multiplication and annihilation in ferrite-cementite lamellae and carbon enrichment in ferrite, which together contribute to the enhanced tensile strength of the steel wire after critical strain.