Abstract: The microstructure and strengthening mechanism of 2 100 MPa grade steel wires for bridge cables during cold drawing were studied using a universal tensile testing machine， transmission electron microscope （TEM）， and X-ray diffractometer （XRD）， and the strengthening model suitable for steel wires at low to medium drawing strain was established. The results show that when the stress variable increase to 1.45， the tensile strength and yield strength of cold-drawn steel wires increase from 1 530 MPa and 1 250 MPa of hot-rolled wire rods to 2 185 MPa and 2 041 MPa， respectively， while the elongation decreases from 6.5% to 2.6%. After cold drawing， the dislocation density of ferrite in the steel wires increases and forms dislocation walls. The pearlite colonies turn to the drawing direction to form a fiber texture， and shear bands （S-bands） appear in cementite lamellae with a large angle to the drawing axis. The measured yield strength of steel wires conforms to the interface strengthening and dislocation strengthening models at low and medium drawing strain， with the interface strengthening and dislocation strengthening being 1 359 MPa and 569 MPa， respectively. The contribution ration of interface strengthening decreased from 88% to 68%， while the contribution ratio of dislocation strengthening increased from 6% to 29%. Although the interface strengthening plays a dominant role in the contribution to the yield strength， the growth rate of dislocation strengthening is greater than that of interface strengthening.

Key words: Pearlitic Steel Wires, Cold-Drawn, Microstructure, Dislocation, Strengthening Mechanism

摘要： 利用万能拉伸试验机、透射电子显微镜（TEM）及X射线衍射仪（XRD）等仪器研究了2 100 MPa桥梁缆索用高强度珠光体钢丝冷拔过程中的微观组织和强化机制，建立了适合中低拉拔应变下钢丝的强化模型。研究表明：当应变量增加到1.45时，冷拔后钢丝的抗拉强度和屈服强度分别从热轧盘条的1 530 、1 250 MPa增加到2 185、2 041 MPa，伸长率从6.5%降低到2.6%。冷拔后钢丝中铁素体位错密度增大并形成位错墙，珠光体团转向拉拔方向形成纤维状组织，与拉拔轴向呈大角度的渗碳体片层中出现剪切带（S带）。中低拉拔应变下钢丝屈服强度的实测值符合界面强化及位错强化模型，其强化贡献分别为1 359、569 MPa；界面强化贡献的占比从88%减小到68%，而位错强化贡献的占比从6%增加到29%，界面强化的贡献占主导，但位错强化的增长速度大于界面强化。

关键词: 珠光体钢丝, 冷拔, 微观组织, 位错, 强化机制