METHOD FOR DETECTING DEFECTS USING MAGNETIC PARTICLES IN A VISCOUS FLUID THAT RESTRICTS THEIR MOBILITY

摘要

Method and composition for detecting defects in a magnetizable test piece which involves applying over the surface of the test piece a relatively viscous slurry of ferromagnetic flakes, preferably in an oily medium, the slurry being sufficiently viscous to restrict lateral mobility of the flakes while permitting rotary movement of the flakes, magnetizing the test piece, and thereafter inspecting the test piece to determine the existence of surface flaws denoted by rotation of the flakes due to reorientation thereof by any stray fields present at defects in the test piece.