小管路焊缝内部缺陷的三维X射线成像

Three dimensional imaging of internal defects in small diameter pipe welding seam by X-ray microtomography

基于X射线显微CT技术,对小直径管路焊缝试样内部缺陷和内表面质量进行了三维观察,发现了5个近球形气孔缺陷.通过三维可视化显示了气孔缺陷的空间位置分布,并量化分析了气孔缺陷的位置、体积、直径、球度等三维特征参数,量化结果表明其中3个气孔为超标缺陷,其余2个气孔为允许存在的缺陷.引入了三维剖切技术,在内表面发现了一个非超标的表面凹坑.在三维重构模型的基础上,通过壁厚分析云图表征了焊缝区厚度分布的均匀性.研究表明,该技术能高精度地对小管路焊缝内部缺陷进行定位、定量和定性分析.

Three dimensional observations of internal defects and inner surface quality for small diameter pipe welding seam were performed using X-ray micro-computed tomography.Five nearly spherical gas pore defects were found. The spatial position distribution of gas pores are demonstrated by three dimensional( 3D) visualization,and quantitative analysis of threedimensional characteristic parameters of gas pore defects,such as position,volume,diameter,sphericity,and so on. The results show that three gas pores are excessive defects,the remaining two gas pores are non excessive defects. A technique of three dimensional sectioning was introduced,and a surface pit with non excessive size was found in inner surface. Based on the 3D reconstruction model,the uniformity of welding seam thickness distribution was characterized by the cloud chart of wall thickness analysis. Research results shows that positioning,quantitative and qualitative analysis of the internal defects in small diameter pipe welding seam with high precision can be realized by CT.