Desarrollo de Procedimientos y Metodologías para Detección de Defectos de Soldadura Utilizando Scan B.

Abstract

The current work was done to show the development of a methodology for conducting the ultrasonic, pulse-echo technique of non-destructive testing through direct contact with the scan B mode. In the first part, it was studied the generalities about the ultrasonic technique, the equipment and techniques applied, scanning modes used for detecting and locating the discontinuities in a weld seam. It was also built and analyzed the distance-amplitude curve (DAC), which is used to discriminate between a defect and a discontinuity. Furthermore, the distance-gain-size (DGS/AVG) curves were studied and used in order to estimate the size of an unknown reflector from a reflector of a well known size. Besides, procedures and methodologies for the calibration of the ultrasonic equipment were developed, to determine the sensitivity of the equipment, surface-condition transfer gain factor and inspection procedures to ensure the repeatability of the test and subsequent evaluation if it were necessary. Once the inspection of welded plates with known defects was conducted, each ultrasonic signal was characterized and related with the size and geometry of the corresponding defect which produced the signals; both, for scan A as well as for scan B modes. This allowed to make an appropriate discrimination among various types of defects that occur during welding.