中文摘要：

利用基尔霍夫近似法建立镁合金壳体内部缺陷的超声测量模型，并利用该测量模型对缺陷回波幅值进行数值计算，获得缺陷波／底波幅值比曲线。在此基础上，建立基于幅值比曲线的缺陷检测理论模型，并对缺陷进行定量检测分析。采用搭建的超声检测实验系统，对含有人工缺陷的镁合金壳体进行缺陷检测试验。结果表明：相比于传统距离增益尺寸曲线定量方法，本实验方法在缺陷定量检测精度和有效检测深度范围上均有较大提高，从而为提升镁合金壳体内部缺陷的定量检测水平提供新的方法和技术途径。

英文摘要：

The model of ultrasonic measurement for defects in magnesium alloy shell was established by using Kirchhoff approximation, and then the numerical calculation on the echo amplitude of defects was conducted by the measurement model, and the defect wave/bottom wave amplitude ratio curve was drawn. On this basis, the defects quantitative evaluation model was presented according to the amplitude ratio curve for defects quantitative evaluation. The magnesium alloy shell containing artificial defects was analyzed by using the ultrasonic quantitative evaluation model. The result shows that, compared with the traditional distance gain size （DGS） curve of quantitative methods, the effective range and accuracy of defects quantitative evaluation are improved by this method. This method provides a new and effective tool to improve the performance of quantitative evaluation on the defects in magnesium alloy shells.