热拉拔工艺对AZ61镁合金丝材组织与性能的影响

采用自制热拉拔装置将AZ61镁合金粗挤压棒材拉拔成丝,研究拉拔温度、道次变形量等热拉拔工艺对单道次拉拔后丝材组织、力学性能的影响规律,并对拉拔过程中断丝情况进行统计,确定能够实现稳定热拉拔的工艺参数范围.结果表明,当道次变形量为15%时,随着温度的升高,丝材中的孪晶组织逐渐减少,强度逐渐降低,延伸率逐渐升高,丝材在350℃时发生动态再结晶.当拉拔温度一定时,随着道次变形量的增加,丝材的加工硬化程度增加,强度、硬度升高,延伸率下降.但当拉拔温度为300℃,道次变形量增加到25%时,丝材发生动态再结晶,使强度硬度下降,延伸率升高.过高的拉拔温度和道次变形量会使丝材发生断裂,随着温度的提高,丝材所能承受的最大变形量逐渐减小.

Effect of hot - drawn conditions on microstructure and mechanical properties of AZ61 magnesium alloy wires

The thick AZ61 magnesium alloy rod was drawn into wire by a self-made hot-drawing equipment. An effects of drawing temperature and deformation degree on the microstructure and mechanical properties of hot-drawn AZ61 wires were investigated. The fracture situation was summarized. The results demonstrated that density of by crystal and strength decrease with drawing temperature increasing when deformation degree is 15%, while elongation increases. Dynamic recrystallization occurs when temperature is 350 ℃. When temperature is constant, with deformation degree increasing, the working hardening increases, the strength increases and ductility decreases. The only exception is that the recrystallization occurs at 300℃ when deformation degree is 25%, causing deterioration ofthe mechanical properties. Excessive drawing temperature and deformation degree results in the fracture of wires. With temperature increasing, the deformation degree decreases gradually.