Zhu Xiaoxiong, Zhou Jie, Hu Chengyang, Wu Kaiming, Shen Yifu, Zhang Yongqing, Jiang Yuedong
College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics (NUAA), Nanjing 211106, China.
Jiangsu Tokyo Rope Co., Ltd., Jiangyin 214445, China.
Materials (Basel). 2023 Mar 8;16(6):2160. doi: 10.3390/ma16062160.
The application of Nb microalloying to high-carbon pearlite bridge cable wire rod steel has always been controversial, especially in the actual production process, which will be affected by the cooling rate, holding temperature and final bonding temperature. In this paper, the experimental characterization, finite element simulation and phase diagram calculation of the test steel were carried out, then the microstructure and properties of different parts of Nb microalloying of bridge cable wire rods were compared and analyzed. The phase transition interval of pearlite during the water-cooling process of bridge cable wire rods is increased due to the refinement of austenite grains, and the significant increase in the end temperature of the phase transition makes the average interlamellar spacing of pearlite increase. The cooling rate of different parts of bridge cable wire rods simulated by Abaqus has little difference. At the same time, Nb microalloying effectively increases the proportion of low-angle grain boundaries, so that the overall average misorientation representing the surface defects is reduced. This helps to reduce the surface energy and increase the stability of the microstructure. Combined with the mechanical properties of microtensile rods, it is found that the grain refinement effect of Nb is greater than that of coarsening interlamellar spacing during hot rolling deformation in actual production, which makes the tensile strength at the 1/4 section increase significantly. The overall tensile strength and area shrinkage of the steel wire have also been effectively improved.
铌微合金化在高碳珠光体桥梁缆索用盘条钢中的应用一直存在争议，尤其是在实际生产过程中，会受到冷却速度、保温温度和终轧温度的影响。本文对试验钢进行了实验表征、有限元模拟和相图计算，进而对桥梁缆索用盘条铌微合金化不同部位的组织与性能进行了对比分析。桥梁缆索用盘条水冷过程中珠光体的相变区间因奥氏体晶粒细化而增大，相变终了温度显著提高使珠光体的平均片层间距增大。利用Abaqus模拟的桥梁缆索用盘条不同部位的冷却速度差异不大。同时，铌微合金化有效提高了小角度晶界比例，使表征表面缺陷的整体平均取向差减小。这有助于降低表面能，提高组织稳定性。结合微拉伸棒材力学性能发现，实际生产中热轧变形时铌的细化晶粒作用大于粗化片层间距作用，使得1/4截面处的抗拉强度显著提高。钢丝的整体抗拉强度和断面收缩率也得到了有效改善。
