Abstract: The strong plasticity technology of 100Si steel Φ14 mm wire rod is studied by measuring the isothermal TTT curve of 100Si steel wire rod and designing off-line salt bath heat treatment process experiment. The results show that the nasal tip temperature of 100Si steel is about 580 ℃， and the shortest incubation period of the isothermal transition is about 5 s， and the isothermal phase transition behavior of 100Si steel is very sensitive to temperature； With the increase of salt bath isothermal temperature （510 - 580 ℃ ）， the tensile strength and reduction of area of wire rod basically decrease； With the increase of off-line austenitizing temperature， the pearlite pellet size of 100Si steel rod increases； Compared with hot rolled wire rod， the distribution of the lamellar spacing of the bottom wire rod by salt bath heat treatment is more concentrated， and the lamellar spacing decreases with the decrease of salt bath temperature； When the temperature is lower than 920 ℃， V in 100Si steel can be precipitated in austenite with the form of VC， and the precipitation of VC in ferritin occurs after pearlite transformation； At the lower austenitizing temperature and the lower salt bath temperature， the mass fraction of VC particles precipitated is less， which can weaken the precipitation strengthening； The hot-rolled wire rod with 920 ℃ off-line austenitizing and 530 ℃ salt bath isotherm has the best balance between the strengthening effect of sorbitic phase and precipitation strengthening effect， the better mechanical properties are tensile strength 1 650 MPa and reduction of area 32.5% .

Key words: Bridge Cable, 100Si Steel, Salt Bath Heat Treatment, Lamellar Spacing, Precipitation Strengthening

摘要： 通过测定100Si钢Φ14 mm盘条等温TTT曲线和设计盐浴热处理工艺实验对100Si钢盘条强塑性进行工艺技术研究。结果表明：100Si钢的鼻尖温度为580 ℃左右，对应等温转变孕育期最短时间为5 s左右，且100Si钢等温相变行为对温度十分敏感；随盐浴等温温度（510～580 ℃）的升高，盘条抗拉强度以及断面收缩率呈降低趋势；随离线奥氏体化温度升高，100Si钢盘条的珠光体球团尺寸增加；与热轧盘条相比，盐浴热处理条件下盘条的索氏体片层间距分布比较集中，且索氏体片层间距随着盐浴温度的降低而减小；温度低于920 ℃时，100Si钢中的V将以VC的形式在奥氏体中析出，且VC在铁素中的析出发生在珠光体转变之后；在较低的奥氏体化温度以及较低的盐浴温度下盘条中析出的VC粒子质量分数较少，会减弱析出强化； 920 ℃离线奥氏体化、530 ℃盐浴等温的热轧盘条具有最好的索氏体相强化效果与析出强化效果之间的平衡，其较好的力学性能为抗拉强度1 650 MPa，断面收缩率32.5%。

关键词: 桥梁缆索, 100Si钢, 盐浴热处理, 片层间距, 析出强化