Weld quality evaluation using a high-temperature SQUID array

This paper presents preliminary data for evaluating weld quality using high-temperature SQUIDs. The SQUIDs are integrated into an instrument known as the SQUID Array Microscope, or SAMi. The array consists of 11 SQUIDs evenly distributed over an 7.5 mm baseline. Welds are detected using SAMi by using an on board coil to induce eddy currents in a conducting sample and measuring the resulting magnetic fields. The concept is that the induced magnetic fields will differ in parts of varying weld quality. The data presented here was collected from three stainless steel parts using SAMi. Each part was either solid, included a good weld, or included a bad weld. The induced magnetic field's magnitude and phase relative to the induction signal were measured. For each sample considered, both the magnitude and phase data were measurably different than the other two samples. These results indicate that it is possible to use SAMi to evaluate weld quality.