The effects of microstructural features on torsional ductility of cold drawn and annealed hyper-eutectoid steel wires were investigated. The patented wire rods were successively dry drawn to ε = 0.79 (54.7%) ~ 2.38 (90.7%). To examine the effects of hot-dip galvanizing conditions on torsional ductility, steel wires with ε = 1.95 were annealed at 500 °C for 30 s for ~1 h in a salt bath. In cold drawn wires, the number of turns to failure increased steadily, showing the maximum peak, and then decreased with drawing strain. During the post-deformation annealing at 500 °C, torsional ductility of steel wires decreased with annealing time, except for the rapid drop due to the occurrence of delamination for 10 s annealing. The decrease of the number of turns to failure would be attributed to the microstructural evolutions, accompanying the spheroidization and growth of cementite particles and the recovery of ferrite in cold drawn steel wires. From the relationship between microstructural evolution and torsional ductility, it was found that among microstructural features, the shape and orientation of lamellar cementite showed the significant effect on torsional ductility of cold drawn and annealed hyper-eutectoid steel wires.

中文翻译：

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拉丝和退火条件对冷拉退火超共析钢丝的扭转延性的影响

研究了微结构特征对冷拔退火超共析钢丝的延展性的影响。将获得专利的线材先后进行干法拉伸至ε= 0.79（54.7％）〜2.38（90.7％）。为了检查热浸镀锌条件对扭转延展性的影响，将ε= 1.95的钢丝在500°C的盐浴中退火30 s〜1 h。在冷拔丝中，失效匝数稳定增加，显示出最大峰值，然后随着拉伸应变而降低。在500°C的变形后退火过程中，钢丝的延展性随退火时间的延长而降低，除了10 s退火会发生分层而导致的急剧下降。失效匝数的减少归因于微观结构的演变，伴随着渗碳体颗粒的球化和生长以及冷拔钢丝中铁素体的回收。从微观结构演变与扭转延性之间的关系，发现在层状渗碳体的微观结构特征中，层状渗碳体的形状和取向对冷拔和退火的超共析钢丝的扭转延性具有显着影响。