基于声发射技术检测镁合金挤压过程动态摩擦研究

Study on dynamic friction in the extrusion of magnesium alloy based on acoustic emission technique

研究了镁合金在挤压过程中的坯料与工模具接触表面的摩擦状态。采用声发射技术对AZ91镁合金在不同挤压速度下挤压成形过程摩擦信号进行采集分析,研究挤压速度对摩擦声发射信号的影响,并分析了挤压型材的组织和力学性能。结果表明,镁合金在挤压过程中声发射信号振幅和能量随滑动速度增加而增加,不同挤压速度下声发射振幅信号平均值为64.4 d B。声发射振幅与声发射能量具有对应性;挤出型材抗拉强度和屈服强度随挤压速度的增加而增加,当挤压速度为10 mm/min时,声发射信号振幅为56.3 d B,抗拉强度为350 N/mm2,平均晶粒尺寸为63.2μm;当挤压速度为40 mm/min时,声发射信号振幅为72.3 d B,抗拉强度为达405 N/mm2,平均晶粒尺寸为53.7μm。为采用声发射技术的实时波形和声发射信号参数的平均值监测金属挤压成形时的摩擦状态提供了试验依据。

In order to investigate the friction state on the contact surface of magnesium alloy when the billet contacts the die in the extrusion process, we adopt the acoustic emission technology to collect and analyze the friction signals of AZgl magnesium alloy in the extru- sion process with different extruding speeds. We have studied the effect of speed on acoustic emission （AE） friction signals and the microstructure and mechanical properties of the extru- ded profile. The results show that the amplitude and energy of AE signals in the extrusion process increase with extrusion speed going up. The acoustic emission amplitude signal un- der different extrusion speeds is 64.4 dB on average. Acoustic emission amplitude is corre- sponding to acoustic emission energy. The tensile strength and yield strength of the extruded profiles increase with the increase of the extrusion speed. When the extrusion speed is 10 mm/min,the acoustic emission signal amplitude, the tensile strength and the average grain size is 56.3 dB, 350 N/mm2 and 63.2 μm, respectively. When the extrusion speed is 40 mm/min, the values are 72.3 dB, 405 N/mm2 and 53.7 μm, respectively. The acoustic emission technology provides an experimental basis for monitorin the friction state in extrusion with real time waveforms and average values of parameters.