Magnetic Particle Testing (MT)
Magnetic Particle Testing (MT) This particular nondestructive test method is used primarily to discover surface discontinuities in ferromagnetic materials. While indications can be observed from subsurface discontinuities very near the surface, they are very difficult to interpret, and often require testing by other methods. Other NDE techniques are usually required for subsurface discontinuity detection and interpretation. However, surface discontinuities present in a magnetized part will cause the applied magnetic field to create “poles” of opposite sign on either side of the discontinuity, creating a very attractive force for iron particles. If iron particles, which are “magnetic particles” since they can become magnetized, are spnnkled on this surface, they will be held in place by this attractive field to produce an accumulation of iron particles and a visual indication of the discontinuity. While several different types of magnetic particle tests exist, th