Evolution Law of Microstructure and Properties during Hot-rolling Process of Ultra-high-strength 92Si Wire Rod for Bridge Cables

According to the evolution law of microstructure and properties during the entire hot rolling process of ultra-high strength 92Si wire rod， methods such as mechanical property testing and microstructure characterization were used to analyze the continuous casting billet， samples before intermediate rolling， samples before finishing rolling， and finished wire rod during the hot rolling process. The results showed that with the gradual improvement of strength and plasticity during rolling， the microstructure refinement resulted in a 45% increase in the tensile strength of the finished wire rod compared to the casting billet. From casting billet to finished wire rod， the interlayer spacing has been refined by 76%， and the pellet size has been refined by 78%. During the entire rolling process， the contribution of pearlite interlayer spacing and pellet size to yield strength were 80% and 20%， respectively. The precipitated phases were mainly carbides of Ti and V， and due to the high temperature during the hot rolling process， the some precipitated phases in the middle of the cast billet underwent dissolution and re-precipitation， resulting in a smaller number and size of precipitated phases in the wire rod.