Testing methods of ferrite content and its universality

The magnetic testing is the most effective and accurate method. However, due to the different manufacturing process and calibration principle, the magnetic testing instrument is not universal. In order to effectively evaluate the weld quality, the secondary standard samples were manufactured by multi-layer surfacing in this study. And the ferrite content of secondary standard samples were tested and analyzed by magnetic, diagram and metallographic testing methods respectively. The calibration curves of the secondary standard samples tested by domestic and imported magnetic testing instruments were obtained. The research result showed that results of magnetic method and the metallographic method were close, whereas the deviation of the diagram method was relatively large. In addition, the calibration curves of different instruments by using the secondary standard samples could achieve a unified evaluation of the testing results.