基于声发射的TiB/TC4复合材料塑性变形缺陷检测

Plastic Deformation Defect Detection of TiB/TC4 Composites Based on Acoustic Emission

目的钛基复合材料塑性差,断裂机制复杂,研发准确的缺陷在线检测技术对控制其服役过程的破坏风险和成形过程的零件质量具有重要意义。方法提出了基于声发射的TiB/TC4复合材料塑性变形缺陷检测方法,首先进行3种不同应力状态TiB/TC4复合材料试样的单轴拉伸试验,以采集声发射信号,通过断口形貌分析其断裂机制,并使用谱聚类方法对声发射信号进行聚类分析,探寻声发射信号与断裂机制之间的关系。结果通过谱聚类可将TiB/TC4复合材料塑性变形过程中的声发射信号分为低频连续和高频突发2类,其质心频率以600~650 kHz为分界。根据断口形貌分析将其分别对应为TC4基体晶粒内位错运动与晶界处增强相TiB颗粒断裂。TiB颗粒断裂的声发射信号占比随着应力三轴度的增大而提高。TC4基体晶粒内位错运动的声发射信号为低频、连续信号,而TiB断裂的声发射信号为高频、突发信号。结论TiB/TC4复合材料塑性变形过程中的声发射信号源机制包括TC4基体晶粒内的位错运动与晶界处增强相TiB颗粒的断裂,通过谱聚类不仅能有效检测TiB/TC4复合材料塑性变形缺陷的产生,还能识别缺陷的形成机制。

Titanium matrix composites exhibit poor ductility and have complex fracture mechanisms,making accurate online defect detection technology crucial for controlling the risk of failure during service and the quality of parts in the forming process.A defect detection method for the plastic deformation of TiB/TC4 based on acoustic emission was proposed.Firstly,uniaxial tensile tests were conducted on TiB/TC4 composite specimens under three different stress states to collect acoustic emission signals.The fracture mechanisms were analyzed through fractographic examination,and spectral clustering was used to analyze the acoustic emission signals,exploring the relationship between acoustic emission signals and fracture mechanisms.The acoustic emission signals during the plastic deformation of TiB/TC4 composites could be classified into two categories of low-frequency continuous signals and high-frequency burst signals through spectral clustering,with a centroid frequency 600-650 kHz as the boundary.According to the fractographic analysis,the signals were corresponded to dislocation movements within the TC4 matrix grains and the fracture of reinforcing TiB particles at grain boundaries,respectively.The proportion of acoustic emission signals from TiB particle fractures increased with the rise in stress triaxiality.Dislocation movements within the TC4 matrix grains generated low-frequency and continuous signals,whereas the fracture of TiB particles produced high-frequency and burst signals.The acoustic emission signal source mechanisms during the plastic deformation process of TiB/TC4 composites include dislocation movement within the grains of the TC4 matrix and the fracture of reinforcing TiB particles at the grain boundaries.Spectral clustering not only effectively detects the generation of plastic deformation defects in TiB/TC4 composites,but also identifies the formation mechanisms of these defects.