In order to perform precise quantitative detection of internal minor defects in additive manufacturing of metal materials based on industrial CT, a quantitative detection method for minor defects in metal materials based on gray-scale variation coefficient of minor defects in CT image is presented. Firstly, based on the analysis of gray-scale features of minor defect regions in CT image, a minor defect image response model is constructed by combining the point spread function (PSF) and noise approximate Gaussian distribution, and the correspondence between the minor defects of different sizes and the local variation coefficient of CT image is derived, and a quantitative detection method based on the coefficient of variation of minor defect region in CT image is established for minor defects of AM metal materials. Industrial CT experiments were then conducted by processing a series of minor defect reference test blocks of different sizes with TC4 titanium. Experiment results show that the defect size and the coefficient of variation reflect a good linear relationship of monotonous increase, with correlation more than 0.996, and the quantitative results of minor defects based on the coefficient of variation method accord well with the measurement results of the microscope, with relative error controlled within 4%. Obviously, this method characterized by simple measurement process and high practical value has improved the quantitative precision of minor defects in industrial CT.

为了基于工业CT对金属材料增材制造中的内部微小缺陷进行精确定量检测，提出了一种基于CT图像中微小缺陷的灰度变化系数的金属材料微量缺陷定量检测方法。首先，在分析CT图像中次要缺陷区域的灰度特征的基础上，结合点扩展函数（PSF）和噪声近似高斯分布，建立了次要缺陷图像响应模型。推导了不同尺寸的CT图像的局部变化系数，建立了基于AM图像中微小缺陷区域变化系数的定量检测方法。然后通过用TC4钛处理一系列不同尺寸的次要缺陷参考​​测试块来进行工业CT实验。实验结果表明，缺陷尺寸和变异系数反映出良好的单调线性关系，相关性均大于0.996，基于变异系数法对次要缺陷的定量结果与显微镜的测量结果吻合良好。 ，相对误差控制在4％以内。显然，该方法具有测量过程简单，实用价值高的特点，提高了工业CT微小缺陷的定量精度。实验结果表明，缺陷尺寸和变异系数反映出良好的单调线性关系，相关性均大于0.996，基于变异系数法对次要缺陷的定量结果与显微镜的测量结果吻合良好。 ，相对误差控制在4％以内。显然，该方法具有测量过程简单，实用价值高的特点，提高了工业CT微小缺陷的定量精度。实验结果表明，缺陷尺寸和变异系数反映出良好的单调线性关系，相关性均大于0.996，基于变异系数法对次要缺陷的定量结果与显微镜的测量结果吻合良好。 ，相对误差控制在4％以内。显然，该方法具有测量过程简单，实用价值高的特点，提高了工业CT微小缺陷的定量精度。