退火处理对冷拉钢丝力学特性的影响

Effect of annealing on mechanical properties of cold drawing wire

为研究退火时间对含碳量不同的钢丝显微组织和力学性能的影响,选取45钢、55钢、70钢及80钢钢丝为原料,以550℃为退火保温温度,研究退火0～80 s内钢丝的组织和性能变化规律,绘出了抗拉强度-保温时间曲线、延伸率-保温时间曲线、不同保温时间的工程应力-工程应变曲线,给出55钢钢丝和70钢钢丝在不同退火时间下的显微组织照片。实验显示,随着保温时间的延长,钢丝的抗拉强度不断下降,但下降的速度越来越慢;钢丝的延伸率不断提高,并趋于稳定。在550℃保温,随着时间的延长,发生回复至再结晶,但是钢丝的纤维组织并不能完全消失,随着含碳量的增大,再结晶温度提高。

In order to research the effect of annealing time on microstructure and mechanical properties of steel wires with different carbon content, adopting 45, 55, 70, 80 steel wire as raw materials, taking 550 ℃ as annealing temperature, to research the microstructure and properties change law of steel wire within 80 seconds, the tensile strength-temperature holding time curves, elongation-temperature holding time curves, engineering stress-strain curves at different temperature holding time are painted, and the microstructure photos of 55,70 steel wire at different annealing time are given. The experi- ments show that the tensile strength of steel wire keeping decreasing as the time increasing, but the velocity keeping down; the elongation of the wire keeps increasing and finally reaching a steady state. Temperature holding at 550 ℃, gTain restoring and recrystallizing take place as the time prolongs. However, the fibrous structure of the wire will not completely disappear. The recrystallization temperature increases with carbon content increasing.