基于超声波的激光熔覆零件缺陷类型分析方法

Analysis method for identifying defect types in laser cladding parts by ultrasonic testing

采用有限元方法模拟了Fe314激光熔覆层中常见缺陷的散射声场,明确了超声波声场与不同类型缺陷相互作用的规律。模拟结果表明:检测方法相同时不同类型缺陷的散射声场明显不同,即缺陷散射声场中反射波、折射波、模式转换波的类型、能量强弱、传播方向等均有差别,但探头接收到的缺陷A扫描信号波形很相似。基于有限元模拟结果,以纵波入射角度和缺陷A扫描信号傅里叶分析结果为主要因素区分缺陷的类型。通过分析不同入射角度下缺陷A扫描信号的傅里叶分析结果,提出激光熔覆层常见缺陷类型判定方法——缺陷A扫描信号动态傅里叶分析法,并通过实验验证了该方法的有效性。

The scattering ultrasonic field of different defects in Fe314 laser cladding coating was simulated by finite element method,and the interaction law between ultrasonic field and different defects was clarified.The results show that the scattering ultrasonic fields of different defects are obviously different,the types,propagation direction and energy of reflected wave,diffraction wave and mode-converted wave produced by ultrasonic encountering defects are different.But the waveforms of A scanning signals of different defects received by the probe is very similar.Based on the results of finite element simulation,the defect types are distinguished by the incident angle of longitudinal wave and the Fourier spectrum shape of defect echo signal,by analyzing the characteristics of scattering ultrasonic fields and the corresponding Fourier spectrum diagrams of defect echo signals,the method of identifying the type of defects was proposed-analysis of dynamic Fourier spectrum diagrams of flaw echo signals.The accuracy of the provided method was verified by the experimental results.