Comparison of the accuracy of the test results of the visible wet magnetic test and fluorescent magnetic test methods for defects in threaded bolts

In the welding process, problems often occur, namely imperfections in the connection process such as cracks. The method to detect these cracks can be done using Magnetic Particle Inspection. The use of the Magnetic Particle Inspection method aims to conduct surface and subsurface testing that will bring up defects in the form of cracks, faults, and holes without damaging with the help of a magnetic field that allows discontinuities to appear using a medium (magnetic particles) that has magnetic attraction. However, the application of Magnetic Particle Inspection on threaded bolts has never been done. After testing, it was found that magnetic testing inspection can be used to read cracks in threaded bolts. Based on the type of particles used with the wet fluorescent method, the accuracy of reading defects in M10, M12, M14, M16, M20 bolts is greater than visible wet where a value of 96.04 % is obtained. In the visible wet method, the reading accuracy is 89.04 %. This is because the defects caused are lighter in color due to being irradiated by ultraviolet light so that they give an indication that is closer to actual defects than visible wet which only uses white contrast paint or WCP and the color of the magnetic particles is black. (author)